Fatigue bending tests at low temperature on welded specimens of 30 mm and 70 mm thickness

(1)

Report SSL3O2

_{FATIGUE BENDING TESTS}

AT LOW TEMPERATURE

ON' WELDED SPECIMENS OF

30MM AND 70MM THICKNESS

Deif t, 1986

TU Deift

Technical University Delt t

¡r. H.G. Scholte Ir. Evan Rietbergen

Department of Marine Engineering Ship Structure Laboratory

(2)

SUMMARY

As a part of the NIL fracture programme. 30mm and. 70mm

w.eldments were tested under fatigue .be.nding at. low temperature

at the Sh;ips. Structure Laboratory. During, fatigue testing

intermediate ClOD-tests were caTrri'ed out' at intervals of 1: or

2. mm. of fatigue crackp.ropa;gation..

With this way of testing 1173 results on fracture toughness

be'havioúr were gained from onl,y 69 specimens. The resú.Lt's give g.00:d additional i.nformat'io.n tO the' co,nveñtional fracture

toughness testresuits and .' a well defined transition

temperature., . whicì divides thepct entiál range of temperature

under wrking conditions' very sharply in a safe and un9af

(3)

LIST OF SYMBOLS

a - crack'length mm

a est - estimated cracklength

a Es - real cracklength mm

B - breadth mm

COD - crack opening displacement. mm

COD-S - COD at the side of the specimen mm

.CTOD .- crack tip opening displacement mm

CTOD 1/3R - CTOD calculated with a center of rotation at 1/3 of the net-section mm CTOD BS . - CTOD calculated according to BS 5762 mm

CTOD Holi.-. CTOD calculated according to the method of Hollstein et al.. mm f req. - frequency Hz

HAZ - hEat affected zone

K stress inténsity fector

KIc - critical stress intensity fáctor in mode i

L -length mm

LT - specimen orientation

n - number of cycles

Pmax - maximum load in COD-test kN

Pmin - maximum fatigue load in fatigue step kN

R - stress ratio

r . -. rotation factor

S _{- span between up and down load in four point, bending} _mm

sigma-y yield' stress MPa

T - thickness mm.

W - specimen width min

x - distance from bottom specimen to side COD measuring point mm

z _{- knife edge height} _mm

- crack tip opening displacement mm

a - yield stress MPa

(4)

CONTENTS 1. _{I;NTRODLJ.CT1ON} SPECIMENS 4 2.1 Material 4 2.2 Welding _... . .

2.3 Geometry and instrumentation

_of

_{the specimens} ₅

TEST EQUIPMENT .

TEST PROCEDURE i

. 7

5 _{PRESENTATION OF THE TEST RESULTS}

. 9

5.1 Sp:ecimen resultS .

. 9

5.2 Results oP 30mm specimens

...

5.3 Results of 70mm specimens

...10

5.4 Comparison

of

_{30mm and 70mm specimens}

...11

DISCUSSiON OF THE RESULTS ₁₂

6.. 1 _{Cal,culat.ion of the COD at the cractip}

...12

6..2 InflOence of intermedjatè

COD on final

ClOD-values at fracture

...14

CONCLUSIONS lIERA TURE lABEL I VII FIGUÄE i - 23 1.5

(5)

1. _INTRODUCTION

This report comprises th.e _{results of the fatigue bending} _tests

at low temperature (fabalt'-test.)'. _{as carried out}

in the Ship

Structures Laboratory _{of the 'Delft, University of Technology.}

The fabalt test programme fOrms part of the NIL-fracture

programme which is the, Outc.h contributIon _{to an international}

fracture toughness programme. _{That programme aims to} _achieve

a _{better definition of material} _{properties with re;ga'rd to the}

occura;ri.ce of brittle fracture or _plastic _collapse _of

structures. This is the more' impo'rtant.whereas the _approach

wit.h 'regard to the acceptance _{of defects is cha'nging from} _the

tendency of absolute absence of defects to tolerated

defect sizes.

With a wide range of different tests to assess material

properties, the _NIL-fracture _programme _tries _to _get

a

realistic set, of requiremen.ts in _connection

an economic, point of vie.w small scale _{tests are}

they _should _give _reliable _predic:tions

of

behaviour _{on large scale.}

with special regard to th.e _tests

to

reliability . of those

predict material behaviour _{on larger scale.}

In the. NI:Lf,racture prog_{ramme accent is given to'thecOD.and}

J-int.egr'al. _{Both are frac t ure toughness} _properties

. that can

be compared' t _results _of _tests _carried _out

at other

laboratories because the relevant _{t:est s are standardized.} _Thé

CTOD,-vaLue.s_ar.eu.g.ed 'toC predict, _{critical crack} _{izes or loads}

for larger _construction _details _by _using

the CT.00-de:sign. curve. A _disadvantage _of _the _OD-test _in

heterogeneous

material is, _{that only a very} _small _amount. _of

material i.s

t est ed. To me ett.h.i.sh an d4c a'p'-a---fat:i-gu ebewdtrí'g _{t e s t at low'}

temperature .(fabal't-tegt) has been _{proposed by Nibbering}

/1/,

/2/ as a complementary and _{alternative test method.}

There are . several ways to perf'orm the fabalt-test. _{In the}

first tests by Nibbering _{the acçert was on 'wide plate testing.}

A serie of small scale _{specimen gave Similer results with}

'which the behaviour of the wide _plates _could _be _predicted..

During _{these small scale bending}

tests brittle steps _occured.

First they were attributed _{to the} _heterogenity

. of the heat

affected zone _{(HAZ) but on furthe;r}

consideration they seemed

to defects. From

preferred, but

the material

(6)

to conform ta the work hardened zone cause.d by the fatigue

load. Outside this zone the material toughness Was sufficient

to stop fractures. Thislabo'ratory situation corresponds to

the reality, where ships and offshore constructions are

continuoUsly exposed to fatigue loads.

Later investigation gave similar brittle steps in 25mm SAW

specimens (1:3/). The basic principle in this way of testing

is t'o have the crack grown though..the net-section of the

specimen at a high load level. Fracture will occur at a bad

spot of low fracture toughness as compared ta t'ha rest of the

section. In this

procedure the

load has ta be gradually lower8d in order to expose every crackti.p point of the section t.o the same stress condition.

At fracture crack'leng'th and load result in a realistic

critical 'stress intensity factOr' (K) value, for which the

material at that temperature cannt be. used safely. I. case

the specimen remains undamaged until the crack reaches half

the specimen widt:h, then the test is concluded with a static

COD-test. The most important advantages 0f thiS Way of

testing are: - the realistic load history, - no difficult COD

measurements during the test, - no problem to calculate the

COD_value at the crack-tip , '- contihuou:s testing of the.

complete speoimen section (-which s:houl.d give more reliable

results, especially for heterogeneous material compositions

like welds)

A problem is the 'comparison wit!h other more commo,n fracture

toughness teats. Apart from that, however realistic the

resulting :KI.c may be, this value loses its applicability In

the demanded toughness zone.

The idea of fatigue bending at low temperature was adapte.d in

an altered version a.g Fatigue COD by Tanaka et al./4/. His

purpose Was to detect the minimum CTOD-v.alue in a small

bzittle zone of the H-AZ. For this purpose face-cracked

specimens were fatig:ued with a constant high maximum load.

and high A-value. When the applied load was high e:nough for

the specimen to break, the crack-tip value was calculated from

the total measured COO. The high maximum fatigue load causes

blunting of t:h'e c-raokti,p. Therefore too optimistic results

may 'be found.. In a later publication Tanaka proposes

restrictions for the R-values an.d the .K -to avoid this

(7)

-2-phenomenon (/5/)'.

More recent

research oP de Soer /6/ which was also directed _to

detect the lowest _fracture

toughness level in a small

embrittled zone, indicated _that _the

continuous Fatigue COD

method stili leaves

many interpretation problems to be solved.

More succes could _{be reached with the method}

of _intermediate

COD-tests..

The idea of _intermediate _COD-tests

has been introduced _by

Nibbering in /3/ to _{improve the actual}

standard COD-test. _As

stated before only a very small _{amount of the section}

is

tasted in the _{standard test.}

This means that the _location _of

the fatigue _cracktip

in heterogeneous Composed material, is

decisive Por the _{fracture toughness}

result of the test. The

principle of _intermediate

COD-tests consists _{of executing} _a

standard COD-test at _{various places of the}

section up to a

certain _ClOD-level. _The

intermediate _{steps are crossed by}

applying a fatigue _load.

Uñder a _{relatively high maximum fatigue load there}

remains the

en fractures at a bad _{spot during}

procedure. Since the Standard

comparison with _{the results of}

standard COD-tests la stili possible.

possibility that _{the specim}

the fatigue step o? the

COD-test is _maintained, _a

(8)

SPECIMENS

2.1 Material

The specimens o?? the faba'lt,-'tes't were manufacturèd from weÏded

X-joints in the thicknesses 30 and 70mm. The plate màterial

in the NIL fracture programme l's a Fe SlONb steel. To assú're

a. good' comparability of the various test results t.he

manufacturer Qq the steel (Dutch Höogovens) Was asked to

deliver the plate with a material composition as h:omog'efleou.S'

as :possibl'e. 'Table I presents the chemical composition of the plate material with the sp'read in' extreme values. ' The

mechanical prop'ePtieìs ar8 shown in table II. A more extensive

descrïption of thé plate material i.n the NIL-fracture

programme hais been given 'in /7/.

In order 'to 'know the yield strength and tensile strength at

diffa'rent'temperatures, tensile tests under displacement

control were carried out on the weld material at -10' and -70

degrees C (/5/;) . The intermediate values 'were obta;lned' with

t:he a;id of resûlt.s of the. BROS I and II research programme

/9/. F.lg.9 shows t.hè results.

2.2 Welding

The 30mm serieS were taken from four' welded strips made f

three rolled plates (nrs.. 58385-005, 58460-006, 5846Ò-009)

The 70mm. serias ws manufactured from three welded strips from

only one rolled pláte. (nr. 62965-013). Detail's are given in

/11/.

The weldS were 'made by Submerged' ' Arc Welding. For the

rootlayera Ma!nuall,y Arc Welding ' was 'applied. The

prehea.tternperature was 120 degrees C, the lnt'er;passtemperature 150 degree.s C. Finally both 30mm and 70mm welded plates' were

p.ostweld heattreat.ed on 570-590 degrees C for respectively 60

and 150 mInutes. 'Table III a t/m g show1s t;he welding

procedure. for the different welding strips.

(9)

-4-2.3 Geometry an,d instrumentation of the specimens

From, _{the' welded plates 45 specimens of 30mm and 30 specimens}

of 70mm were manufat.ured. _{The specimen geometry is} _given _in

fig2

for the 30mm specimen and in fig.3 for the 70mm

specimen. Both series had a short mechanical notch of resp.

10 and I'S. mm sitUated at the. centre of the weld. This

position was chosen because it _{is. univocel to define, this} _in

contrast to the. fusion line or the HAZ. The 70mm specime.n'.has

a B/W=0.S, which equalS. the _ratio _recommended _for _th.e _BS:

standard test specimen (/12/).. _{For the 3Ommspecimen B/W was}

lowered to 0.33 because otherwise _{.he. craokgrowthpath} _wou.ld

have _been t'o _{short to obtain enough measuring point's.} _The

numbering, of 'the,.. specimen successively consists of: a

weldmerit number;, _{the orientation of the speclman.(} _{see fig.4).;}

a serial number. (e.g.. 8 'LT SL

To measure the COD a clip' gage was used which was. fitted.

between fixed knife edges 'at the cra.ckmouth of the _specimen1

'A c.lip.gag.e (MTS) w.ith a range of 3.5 mm w s used for

measuring _{the. COD at some of tche.3Ornm spec;imen,s.,} _{A clip gage}

(MTS), with a range of 12 mm.Was.used for the 70mm specimens

and the _{. greater part of the. 30mm. specimens.}

F'ig.5 shows a detail of the i.nstrumentatjôn of the _specimen.

In addition to the clip gage a COD-measuring device ' at the

side of. the specimen ca:fl be seen. In fig.5'. also sorne

measurement wires canbe dï'st'inguished _which _we;re _used _to

detect, the _{crac'kleng:th based Upon' th:e potential drop} _method.

Bat:h .supplernentarymeagurrn,,g _{appeared t.'o} _obta.i,n _unrelj.abl.e

results and they will not be taken 1ñt.o account in the

discussion of .theres,ults of this investigation.

(10)

-5-3. TEST EQUIPMENT.

For the fabalt test programme two vertióal servo-controlled

fatigue test machines were,

used.

A 350 KN machine for the

30mm specimens and a i.000kN machine for thè 70mm. specimens

(See, fig.'6,) . The adJustmeit of fatigue load and the execution

of the COD-tests in the first tests of. the 30mm s1pecimen9

:(.nrs. iLl l-5,. 2LT 13-16, OLT

27-36)

weré

carried out

manually. The adjustment during the testing of the 70mm

9ped±mens and the remaining, 30mm series was done by computer

con:trol. The computer was alsp used to gather measurement

data. 0f all COD-tests làa:d-COD plots and time-COD plotswere

made On x-y-recorders, respectively x-t-re,corders.

The experime:nts were carried, out, at low temperatures over' a

rànge from -100 degrees C up to -20 degrees 'C. Two co:o:ling

dév'ices were applied. An alcohól cooling device Was applied.

for the range 0f -20 degrees C to -60 degree C with an

accuracy of about 0.5 degrees C. Lower temperatures were

òbtàin.ed with an accuracy of about 2 degrees C by means of a

nitrogen iñstallation.

(11)

-6-4. TEST PROCEOUAE

As stated in the introduction there are several ways to

perform the fabalt-test. First it

j8

possible to adjust

continuously the maximum fatigue load in such a way that a

constant net-stress at the craòktip is maintained when the

crack moves through the section. This òonforms tO the

procedure of _{Nibbering and Schalte in /3/, although in theie}

tests the maximum load Is only adjusted three times. Tanaka

applied a similar procedure,. However by applying continuous

loading the section point.s are not testéd under equal

circumstances. Therefore süch procedures are only suitable

for detec.ting. the minimum: CTOD iñ a smàll known area.

Moreover this way _{of testing raise some prolems concerning}

the: interpretation of the test results. (see /6/). The

possible. influence of the load his tory, an influence. of. AK and

R on the results and difficulties to calculate the COD

cracktipvalue are the ma1n ones.

Because of these problems and for a better comparison with the

other results in the NIL-fracture programme, the fabalt-test

woe carried out by applying intermediate COD-tests. In that

test th.e load is raised until a prefixed COD-value at the

cracktip jg _reached. _When _the _fracture.

toughness of the

material at that place is sufficient to resist that amount of

deformation without cracking, the specimen Is unloaded and the

test je continued by making a next fatigue step C say 2mm) . A

fatigue load _{is applied thàTtcTOrreqpondg to the h7ilher loads}

that occur in practice, so there is po:ssib:ility that

fracture occurs at a bad spot in the material. _{On the other}

hand: the fatigue load should: not influence (too much) the

COD-results. The advantages of thie procedure are clear.

Although there is no continuous testing of the. sectio:n, the

chance to find a bad spot is Increased. _{The choice of the}

prefixed ClOD-value an depend on requirements of

Classification Societies or calculatiöng. When the specimen

has not fractured when the crack has reached half the width

the test Is concluded with a COD-test till fracture. _{At that}

moment the e;peclmen dimensions correspond to those of the BS

5762 /12/. So the result is that of a standard COO-test.

For the 30mm specimens the fatigue step size was set on 1 mm

and for the 70mm specimens on 2 mm _These _step _sizes _were

(12)

-7-visually perceptible and no other cracklength measurement

method was required. Afterwards often the real cracklength

appeared to be somewhat larger. However because good crack

front marks appeared on the fracture surface (fig.9a),

corresponding to the successive intermediate COD-tests, all

results could be evaluated with the real craciclength.

Cracklength and stepsize are therefore not critical.

The maximum fatigue load has been selected so, that, for that

particular temperature, after every fatigue step the yield

stress was reached in the net-section of the specimen, based

on a linear stress distribution (sigma-y line). This fatigue

load corresponds to the maximum fatigue load permitted to

produce the fatigue notch In the standard specimen according

to BS 5762. In fig.? the maximum fatigue load and

corresponding K-values are shown as a function . of the

craoklength.

With the selected frequency (4 Hz) and stress ratio (A0.3)

every fatigue step needed 1000-2500 cycles. This resulted in

the possibility to perform one fabalt-test every day. It was

fortunate that in this investigation only a slight retardation in crackgrowth was observed at the beginning of eaçh new step.

Although no crackgrowth retardation was noticed , the fatigue

load in the first tests was as high as .75% of the maximum load

of the previous intermediate COD-test, (nrc. 8LT28, 29, 30

and 31)

In the intermediate COD-tests the COD-value which had to be

applied after each fatigue-step had been calculated on the

base of a center of rotation at one third of the net-section

width (r1/3) (see

fig.8) . Later these values have been

corrected with 88 5762. This procedure was necessary because

the CTOD must be continuously calculated during the

experiments in order to to minimize the scatter in applied

intermediate CTOD-values..

(13)

-8-5. _{PRESENTATION OF THE. TESTRESULTS}

5. 1 Specimen results

The resulte and data particulars of the fabalt-expe:riments are

collected in report /13/. In the presèn't report several

representativ.e reuita from /13/ have been inserted see fig.9

and 10. The figures 9e. and 10e give : general information,

load, te.stcondltion.s, dimensions etc..; additional remarks; a photograph. of the fracture surfce.; a table with ail tes.t

data. In figures 9 and 10 sorne illustrating graphe have been a:dded. The, first graph shows the load history as a function

of the crackl.ength, and the second ne the CTOO as a function

cf the c:rackie.n'gth.

In the present report all test results are given 'in table IV

-VII for the 30mm specimens and table VIII för the 70mm

specimens. Thfse tables comprise: testtemperature; total

number of cycles; number of COD test at a specific average

int'ermediat:e ClOD level, wlhich is given inthe next columns;

crack.leng.th and load at fracture; moment of fracture; a

critical K-value for the specimens which fractured during

fatigue; CTOO. values at fracture.

For the òalcu,lationof the ClOD-values three different methods are applied:

A linear interpolation between the measured displacement

at the orackmout.h and a center of rotation at one third

0f

the

net-section width (r=1/3 as shown in flg.81.

The compliance method according to BS 5762; 1979, /6/,.

/12/.

The mèthod of Hellstem, Blavel and Ulrich, which is based on a linear Interpolation between the measured .displaòement at

the crackmout'h and the center of rotation. The difference

with a. is the location of the center of rotation, which now

la. given by formula r=O'.48VCTOD. This method' .s'huid give

satisfying results compared to BS 5762 /14/.

Next to the presentation in table IV - VIII the results. have

also plotted In graphs, Which give a complete overview of the

testresults.. Fig.11 gives the results for the 30mm and 70mm specimens based on the assumption r=1/3, which was used during

testing of the specimens. These results corrected wIth 86

(14)

-5762,, _{re p1otted in fig.12}

and 13. _{The various symbols} _used

in _{the figures are explained by the}

scheme in the left _{top of}

the figure. For some _specimen _the _clip

gage range wá9

insufficient t'o meagur _{the total COD at}

fracture. In that

ca'se the values given _{in the fig.1i,12}

and 13 are based _{on the}

maximum COD which _{could be reached with}

the used clip gage.

An arrow i.ndjcat;es _that _'the _real

CTOO will _be _above _the

plotted point.

5.2 ResigUe of 30mm _specimen.g

To _interpret _the

results as presented in _{fig.12 is a rather}

complicated matter. _{Therefore in fig.14 only ClOD}

values at

fracture _{calculated according BG} _{5762 are given.}

In addition

regression lines were _{calculated tlh:rough the}

fracture _points

of _{the various we,ldmentg.}

These are plotted in _fig.1'S. _From

this figure it _{appears that one weldment (8LTa}

series) has a

significant _{lower fract.uretoughness}

as compared to the other

three. weldment,g. _{The result,g of the}

specimens from the other

weldmentg will be _{Considered as one}

group, although the ILl

weldment was somewhat 'better at higher temperatures _and _lower

at low _{temperatures.}

Only few results _{are available in the}

higher temperat:ure _region.

However it seems eviden,t that at

about -40 _degreee _C _the

transition to _{extensive plastic}

deformation occurs. _{For the} _8Lra

weidment this _transition

temperature is _{about 20 degrees C} _higher.

The caúse of this

difference is not yet clear. _{The differences in}

platematerial

composition and _welding

procedures are too small to _explain

this behaviour.

5.3 Results of 70mm specimens

Fig.16 ehows the _CTOD-values _at

fracture for the' _70mm

specimens. _{In contrast to the 30mm specimens}

this figure does

not reveal any _signific

difference _between _the _varioUs

weidments However, _{when testing the 70mm}

specimens another

phenomenon _appeared _Which _can

be _i.11ustpated _when _lines

calculated with linear _{regression are plotted.}

The CTOD at

fracture seems to be _influenced _by _the

height of _the

intermediate ClOD. The lower line _{in fig.17 contains} _all

results while in the upper line the results _which _might _bO

infl:uenced by a _high _{intermediate cîoo have,}

been e'xcluded.

The _phenomenon _will _be

(15)

paragraph.

5.4 Comparison of 30mm and 70mm specimens

in fig.14 and 16 three different areas C8:fl be distinguished.

There is firSt an area with low temperatures where fracture

during fatigue is- possible. This brittle z-oñe runs upto -70

degrees C for the 30mm specimens end upto -80 degrees C for

tih.e 70mm -ones. This _is followed by a second are.a over a

temperature range of about 35 degrees C up to a.n upper limit

of about -40 degrees C. in this area the scatter in the

C-TOO-values i-e high due to a large increase of the upper

values and an almost- .naglectibl-e ncrease of the lower ones.

Finally ove-r .a very' small temperature range we can find a

sudden -disa:ppearance of all lower CT-0D-values-, resulting in -a

well, defined transition temperature. This transition

temperature is about -40 -degrees. C aswe-il for the 30mm

Specimens as for the 70mm specimens and divides the- potential

range of temperature under working conditions very sharply in

a safe and un-Safe region.

-A further look on the second area with increasing scatter in

CTOD-vajues shows a dif-ferènóe in behaviour between the

30mm-and 70mm specimens. Fig.18 shows that the fracture -toughneea

of the 30mm series is considerably -lower than that of the 70mm

-series. An effect of increasing constraint with thic:kness'es

does not appear at _-all, Probably this is caused b;y t:h:e

difference In specimen geometry: _{B/W=0.33 for the 30mm serie-e}

and BJW=0.5 for the 70mm se-ries-. Another poss.i.biity is that

the- welding procedure is- more benif'ioial for th.e great-er

thicknesses, of cour-se this is quite haphazard..

'Influence- of the height 0f intermediate CTOD-vaIues- could not

be as -clearly distinguished -for the 30mm specimens as for the

7-Omm ones, altho:ugh also he-re some -bad -results could be

-explained by this phenomenon. This will be discussed in 6.2.

In fig.19 the calculation method using the assumpton r1/3 is

compared to _the BS 5762 -for bot-h plate thicknesses.

Especially i-n the -lower _{toughness region- the diqference j}

(16)

6. _{DISCUSSION OF THE}

RESULTS

6.lCalc.ulatjon of the _{COD at the cracktip}

One of the problems in applying COD-tests _is _the _calculatjo,n

of the COD _cracktip _value _from _the

measured COD at the

crackmouth. _{De Boer /6/ used} _the

BS-compliance method and

plotted _the _{load-COO curve of the}

actual test on graphs with

load-COO curves for various CTOO-values. _{This working} _method

is very

_{labørjg and difficult}

to automatize. _{TherePore in}

this investigation the _{simple assùmption of} _a _fixed _location

of the center of rotatjon _{at ¿'=1/3 was maintàjned.}

The CTOD _calculation _aÒcord1ng _to _BS

5762 consists of an

elastic part and a plastic part. The elastic part is

calculated with a standard formula, based on theoretica,1

models, but the factor 2 _{in the denominator} _was

evaluated by

experimental data. From the plastic component _{of the total}

COD the plastic _{one of the ClOD}

is! Òa.lculated by taking a

center of rotation of 0.4 _{of the net-section Width.}

For small

CTOD values the plastic _{part will be} _small _and

the elastic.

part will dominate. _Fig.20 _gIves _the _elastic

part as. a

percentage of the total _ClOD _which

_illutrateg

the fast

growing _influence, _of _the

plastic part with increasing _ClOD

values over 0.2 mm. _{The center oP} _rotation _of

the elastic

part is about 0.1. _{This explains the great}

differences In

ClOD-values for the lower _region, _for _the _two

calculation

methods 88 5782 and _r=113. _{However, with increasing}

toughness

and therefore increasing _{CTOD-values the contribu:tjon}

of the

plastic _component _{becomes larger and larg:er.}

Because.th,e SS

5762 assumes a center _{of rotation at 0.4}

of the _net-section

width _{the difference.s}

between the CTOD.-v'òlueg _{calculated with}

r=1/3 and BS 5762 become _{smaller for larger}

CTOD-valueg. At

large _CTOD-vaJ.ueg _r=1/3

becomes conservative _{compared to BS}

5762. It should 'be _{realized that the center}

oP _rotation _of

the plastic part _(r=O.4 _is _still

subject of discussion

(/15/).

Because earlier investigation of Guyt /14/ _{indicated: that} _the

method of _{Holistein, Ulrich and Blavel gives similar}

results

as the SS this method _{was also taken into}

consideration it

gives, a simple _formula _for _the

center of _rotation

(r=0.48\flT5)

which makes fast data _Processing _possible.

(17)

-Therefore all data have been evaluated using this method. In

fig.21 the CTOD-values are compared on basis of r1/3. The BG

values, are grouped in two separate lines for the 30mm and 70mm

specimens. Probably an influence of the B/W ratio is the

cause of _{this phenomenon, either in the 96 calculation or at}

r=1/3. _{Using the BG method no influence of a/W ratio could be}

determined in contrast to the Holistein et al. method. The

lines for the latter in fig.21 are calculated for the 30mm

specimens. The results 0f the 70mm specimens appeared to

remain in the same hatched region. In fig.21 is indicated how

the curves will shift with the change of the indicated

variables.

The correspondance between the results of the method 0f

Holletein et al. and those 0f the BG is satisfactory up to

CT0D0.5 mm, but CTOD values larger than 0.5 mm are. 0f less

practical interest. Compared to r=1/3 the BG is conservative

up to 0.75 mm for the 30mm specimens and up to 0.9 mm for the

70mm specimens.

In fig.22 the location of the center of rotation as a function

of the CTOO is given for various calculation methods and

experimental data. The experimental data are obtained by

measuring the ClOD directly with advanced measuring techniques

116/, /17/. Compared to these experimental data the simple

assumption

r1/3

is conservative from

CTODO.1

mm. The

correspondance between 88 and Holletein and these experimental data is bad up to 0.7 mm.

Although it is not the intention of this investigation to

discuss the 88, apparently great differences appear in the

calculated COD cracktlp values up to 0.5 mm, depending on

calculation method used. As these lower ClOD-values form the

most interesting range for the fabalt-test, maintaining of the

COD-concept remains a handicap in the present fabalt test

procedure, but it is inherent to COD-testing n general.

(18)

-6.2 influence of intermediate CTOO on final ClOD-values at fracture

In fig.14 and 16 the results that might be influenced 'by

intermediate COD-tests aré ' marked. with a symbol. The

comparative low values of these results can be explaind b'y

three different effects. . '

Above a certain level of plastic deformatian the

intermediate COD-tests will decrease the fracture toughness at the next measuring points of the net-section to such an extent

that the C.T0D at fracture is 'reduced.

With a higher intermediate CTOD level the probability is

'raised that the cracictip is located at a bad spot with a

fracture toughness j:L8t under that particular intermediate

CTOD level.

HIgher intermediate CT0D-va lues Increase the necessary

numbér of cycles for the additional growth of th.e fá.tigue

crack, resulting in more strain hardening.

That great differences in fracture toughness do occur in one

section is il.luatrated by the result of 8LT37 .(fig.23) .' 'Here

two locations 'of instability can be d:isti.nguished. The first

Praoture at an' intermediate COD test could stop due to load

relaxation and better material quality. ' The latter came

forward when the test was co'ntinue'd and completed with a

standard COO test which resUlted in a good tou:ghness value.

However, with the effect of raised probability in a dominating

role, one shòu,Id expect, that, although a high intermediate

ClOD level 'will causa lower' ClOD values at fracture because

more' bad spots will be detected1 the fracture 'ClOD ' values'

should increase with higher temperatures. As can be noticed

from fig.14 and 16 this is not the case. Particularly the'

fracture ClOD values at -40 degrees C are not 'in line with on

increase in fracture toughness at higher temperature;s. One

has t. conclude that the' influence 0f the' load history and in

pa:rtiòular the height of the foregoing intermediate

CTOD-values contributes to the decrease of fracture toughness

in order to axpla:in this phenomenon. The amount ' of the

contribution of' each particular possibility is difficult to

determine. With the present data lt is n'at possible to

establish which of the three phenomena is dominating.

(19)

-7. _{CONCLUS;IÒNS}

At lower temp,e,r'atures, _{low stress brittle. fracture. ocoured}

'during fatigue. _{The critical t:empera'ture is -70}

degrees C for

.30mm specimens and. -80 _{degrees C for 70mm Specimens.}

In a transition, _{zone from -70 up to -40 degrees C'fracture}

toughness slIghtly' increàses, _{while a great} _scatter _in _CTOD

results can be. fou:nd in that' area. Therefore thl,s area n

certainly not be indicated', _{as. safe from a} _fracture _toughness

point of view.

The transition, from low t.o high _{fracture toughness, values}

takes place in 'a small temperature _interval _(1.0 _degrees _C)

Th'i temperature is for both plate thicknesses -40 _{degrees C}

and can be interpreted as a sharp and accurate boùndary

between the safe and unsafe area.

The ' _{results indicate that the loadhisto'ry, in particular}

the level of pea:k.load:.s or intermed:iate _{CTOD values.} _inflúences

the CTOD value at fracture. _{It is not possibl.e yet to give a}

quantitative explanation for this phenomenon.

The ClOD' results, in the transitjo:n _{zone of -70 up} _to. _-40

degrees C are significantly lower' fo,r the 30mm specimens

compared to the 70mm specimens.. _{HowPar this can be} _explained

'by _differences _in

specimen 'geometry and/or influence of the

welding_pjQced.ure is not -et--.e-xami-neth- -'A- further

nvestigation is recommended,.

Calculation of _{the CT0D values with, the assumption} _{of a}

center of rotation at 1./3 of the. net-section width leads to

significantly higher results _{u.p to CTOD values of about 0.8mm,}

compared to the calcul.a'tio, according BS _5762.

(20)

-LITERATURE

/1/.N.ibbering,. J..J.W., Lalleman, A.W.,"Lo.w cycle fatigue tests

at low temperature with E.G.-welded plates",, 11W-doc..

/2/

Nibbering, J.J..W. et al.,"Britt.le fat;i.gue in the H.A.Z

of E.S.-welded plates subjected to low cycle., fatigue",

11W-doc.

X-67o-72..

/3/ Nibbering, J.J.W., S'cholte, H.G.,"Real.istic testing, of

welds by f'atg..ue' bendi'ng at l.cw temperature", 11W-doc.

x-1014-82.

/4/ Tanaka., K.., Sato, M'., Ishi:kawa;, T...,"Fatigue COD and Short

crack arrest tests", Pa:per 18,

mt.

Conf. on.Fracture

Tougness Testing., The Welding Ipsttu't'e, London. 1982.

/5/ Tanaka, K., Ishilsawa, T.,"DeveÏopme:nt of fatigue CTOD test.

for investigation of brittle regions in welded. joints", Sixth

mt.

Conf. on Frac. (1CF6) New Dahu, India 1984.

/6/ Boer, R. de,"The detection of local. embri.ttlemen't in

welded structures", final thesis department of Material

Engineering, T.H. Delft, april 1984.

/7/ Kinjet,"Levering van. Fe 510 Nb aan NI.L,/TNO t.b.v.

int.e.rna:tior'aa:l breuktaaih.eid'eonderzoek" PG 84-08 (in Dut.ch)

/8/ Spanjer, W..,, "Tensile tests executed at -10 C and -70 C on

FeSlONb pl,atemateri.a.l and . weld metal", TNO-rep.ort

85M/01i'g./SPA/VLT, PG .85-01 ₁₄ January1985..

/9/ Ronge:n.j H.J .M'. , "Ge:g'evens van treIs,pro:even aa:n Fe5lONb",

Mem. 3364106, Pg 85-03, ?S januari 1985 (in Dutch).

/10/ Spànjer, W..,"Tens:i:le tat.s: executed at -10 .0 a.nd -70: C on Fe5lONb base mate.rial",ÏNO-report 84M/10053/SPA1VLT, PG 84-13, 7 September 1984.

/11/ K.onin:g, _{C,"NIL-bPeruktaa1heidsonderzoek./Nede;rlandS}

programma. Uitnameplan en type proefst.ukken", TNO-re,port

(21)

/12./ "Methods for

Crack Opening

_{D'ispi,acemènt Testing", BS}

₆₇₆₂

British Standards

_{institution ssi, London}

_1979.

/13/ Aletbergen,

E.

_{v.,"Expe:rjment.ai data of fatigúe}

_bending

tests

at

low

_{temparatupe".,,}

_App.endi.x

_to

_report

_{302, Ship}

Structures Laboratory repOrt nr.

_{302b, Delt 1986.}

/14/ Gu.yt.,

_{J.,"Theo'retjsche. en experimente].e analyse van enlge}

aspec:ten. van de COD-proef

_{eIn haar toepas's:ing",, final}

_{theslis, at}

Department of Naval Arc:hitecture

_{T.H.Delft, 1980 (in}

DUtchi.

/15/ Matsoukas, G., Cotterell,

_{B., Mai, I.W.,"On' the}

_plastic

rotation

constant

used

_{in stalndard COO testi",}

_mt.

_iourn.

of Frac.

26,

11984..

/16/ Inglham, T., Egan,, G.A.,

_{'EllIott, O., HarrIson,.T.Ö.,'Th}

effect

of

geometry

_{on the Interpretation. of COD test}

_data",

Prao.

Appl.

of Frac.

Mech.

to Press.

Vess.

Tech.,

mIst.

of Mech.

Eng., 'London

1971, p200-208.

/17/

Veerman,

_{C.C.,, Muller, T.,"Th,.e}

_{location of the äpparant}

rotation axis in notched bend

_testing",

Enlg

Frac.

_M'ech.

(22)

Table I. Chemical composition of heat and plates. Ladle analysis % X I0 Heat no. C Mn P S Si Ai tot Cu Sn Cr Ni Mo Nb N % .x10 91251 184 H 1323 0113 010 401 056

017005 031

026 002 027 0036 Plates

Element

VÎS

Lower and upper values Scatter

C 0.187% 0.173. - 0.193% 0.02% Ñn 1.297% 1.267 - 1323 Oi.05'6% P 0.014% 0.013' - 0.014%. 0.001%. s 1 0.Ó07% 000'6

000%

0,.Ô02% Si b.. 398Z 0.387 - 0.421%. 0.034%

Alt

0.048% 0.041 - 0.050% 01.009% Ce 01.4%

_O.OTO

-. 0...01L7Z__

_-0.07

Nb 0.029% 0.026 - 0.031% 0.005% N 0.0053% 0.Ó04:8 - 0.0059% 0001 1%

(23)

Table II. _{Mèchanical properties of plates for fabrication of test specimens.} Thickness tj Specimens Rolling number Dimensions Re (N/rn2) Rm

(N/2

Elongation (Z) Charpy-V - O J-value ( C) -L (=) V (=) T (=) 30 1LT 58385 6000 1400 30 30 2LT 58385 6000 1400 30 389 567 30.6 89 -40 .371 ₅₄₈ 32..5 95 -40 30 8LT 58460 6000 1400 30 391 563 28.6 107 -40 384 570 27.2 97 -40 70 liLT 62968 3000 1400 70 386 550 29.0 7T -40 387 549 27.0 136 -40

(24)

laboratory report

8424/35/O.N. 35.6.6731 T.N.O. -Apeldoorn

Project-Fracture Mechanics Tests

. Welding Procedure Record

Teetsample Welding process : Welding position: Preheat Interpass temp. : Filling material: - Eeattreatzoent : joint preparation SOC--.... P.S. box 6 øO#A I&den Ihe AOthSdlfidS fspcftO. 841019 i? - 1G plate 30; PeE 355 kT

S.M.A.W. (manual) and S.A.W.

1G

120CC 150°C

S.M.A.W. (manual): Electrode

S.A.W. : Wire

stress relieved Flux

570-590°C/60 min.

noi iarase

constructie

groep by

Kryo i SW 60 P 240 layers as welded

-I

O)

-4 o' D. e H H H a'

caz

e-QQ. mec wD I,

o

ro

f ID

-Q.

C

l'i

ID -.

-40

3

e ID D 3 to e

Layer Electrode Dian. Amp. Volt. R.Ó.L. speed Current

Wire/Flux ma cm

in.

i 1(ryol 31 110 26 12 ac 2 Xryoi 4 165 28 25 - ac 3 SW6O/P240 4

500.28

- 50 deep 4-8 SW6O/p240 4 600 32 50 dcep 9 SW6O/P240 4 _'0 ₂₈ ₅₀ _deep 10-14 SW6O/P240 4 .00 32 - 50 deep /

.fter welding la 1-8 , the weld has been gouched out Untill a dep . . f 5 ma, at side of layer 1.

Octobe 18th 1984

(25)

Iaboratozy report

o. 84M/35/O.N. 35.6.6731

died T.N.O.-Apeldoorn

Do. Project-Fracture Mechanics Tests

«t Welding Procedure Record

- Testsample s - welding process * - Welding position: - Preheat s - Interpass temp. s - Filling material: Heattreatment s joint preparation :

,/)J

Octod 18th 1984 d quimy cSsd -7/ Iepcftoo. 841017 2F - 2G plate 30mm FeE 355 kT

S.M.A.W. (manual) and S.A.W.

1G

120°C

150°C

S.A.W. : Wire

570-590°c/60 min.

- Kryo 1

- SW 60

- P 240

layers as welded

1-9 , the weld has been gouched out ma, at side of layer 1.

-4 a, o. ID H H H o. rs4)

Layer Electrode Diam.

Wire/Flux

Amp. Voit. R.0.L. speed Current

cm sVndn.

I--I

1 Knyol 31 110 26 12 ac 2 Kryol 4 165 28 25 ac 3 SW6O/P240 4-9 SW6O/P240 lo SW6O/P240

.4

4 500 600 500 28

-32 28 50 50 50 dc/Ep dc/Ep do/Ep

CD

11-15 SW6O/P240

.4

600 32

-

50 do/Ep of 6 After welding i untill a de

(26)

84M/35/0.N. 35.6.6731

disid T.N.O. -Apeldoorn

dne ProjectFracture Mechanics Tests

bJsct Welding Procedure Record - Testsample - Welding process - Welding position: - Preheat - Xnterpass temp. - Filling material: Eeattreatment joint preparation so.--.-. 1 Kryo1 2 Kryol 3 SW6O/P240 4-10 SW6O/P240 il SW6O/P240 12-16 SW6O/P240 After welding untill a a

r.nty& quality co l departm.nt

°'

Octo.- 18th 1984

r.poein 841022

SA - 83

plate 30mm; FeE 355 kT S.M.A.W. (manual) and S.A.W.

1G 120°C

150°C

S.Z4.A.W. (manual): Electrode - Kryo i

S.A.W. : Wire - SW 60

stress relieved Flux - p 240

570-590°C/60 min. WE,DING DATA 12 25 layers as welded 50 50 50 50

r 1-10 , the weld has been gouched out of 6 mm, at side of layer 1. ac ac dc/Ep dclEp dc/Ep dc/Ep cn D (D

w-oc.

I-'. l-'

3D

DD D n hi

t

o

lo

Il lCD cDL'

ro

-43 (j)3 n CD C) 3 CD D 'n

rI

n CD 1 CD (n 31 110 26 4 165 28 4 500 28 4 -'0 32 4 5,. 28 4 .00 32

constructi e

groep by

laboratory report AA leiden the nel%eflands Layer Electrode Wire/Flux

Diam. Amp. Volt. R.O.L. speed Current

(27)

laboratory report

r.rno. 84M/35/O.N. 35.6.6731 cSl.n T.WO. -Apeldoorn

Project-Fracture Mechanics Tests Welding Procedure Record

- Testsample - Welding process - Welding position: - Preheat - Interpass temp. - Filling material: - Heattreatinent

pì

t;;

,e,tflD. 841024

aC-SD

1G

120°C

150°c

S.A.W. : Wire

570-590°c/60 min.

WELDING DATA

- Kryo i - SW 60

- P 240

After welding layr 110 , the weld has been gouched out untill a dep.1(of 6znzn, at side of layer t.

ori. _October

(th 1984

,ntrnI quality control dezrtment aberatoiy .,ctlan

co

-I

o

Layer Electrode Diam. amp. Volt. R.O.L. speed Current

Wire/Flux mm cm cirVmln. 1 Kryol ₃₁ 110 26 ₁₂ _ac 2 Kryol 4 165 ₂₈ ₂₅ - ac 3 SW6O/P240 4 500 28 50 dcep 4-10 sW60/P240 4

,-00

32 50 dcep 11 SW60/P240 4

400

28 50 dcep 12-18 SW6O/P240 600 32 50 dcep

(28)

cid.zno. 8424/35/O.N. 35.6.6731 cfl.nt T.N.O.-ApeldoOrn - Testsample - Welding process - Welding position: - Preheat - Interpass temp. - Filling material: - Heattreatment Layer Electrode Wire/Flwc 1 ICryol 2 Xxyol 3 SW6O/P240 4-37 SWGO/P240 38 SW6O/P240 39-55 SW6O/P240

.__

loo___._Y

After welding laye untill a dept

Icden. Octob- 18th 1984

repodan. 841171

11 A - 11 B

1G

120 oc

150CC

S.A.W. : Wire stress relieved F1WC 570-590°C/150 min. a a

aae

cons1uctîe

groep by

- I(ryo i - SW 60 - P 240

Diam. Amp. Volt. _R.O.L. speed current

ann cm cnVmin. 31 4 4 4

4.

4 110 175 475 ac ac 30 50 dc/Ep 75 32 50 dc/Ep 30 50 dc/Ep 32 50 dc/Ep

-37 , the weld has been gouched out 7 mm, at side of layer 1.

00.

.ubjed

Pro3ect-Fracture Xechanics Tests

Welding Procedure Record

layers as welded

joint preparation

jwù AA

* M5e:Iands

(29)

label 111f' Welding procedure 70mm specimens 1l;LTb-aeries Bpecifflens

11LT9 -. 11LT18

eider no. cenireot no. eubJ.st ieldegi. _Octe cenkot

-I

Teatsample i Welding process Welding position Preheat s Interpasa temp. t Filling materials Heattreatinent.

i-After welding laye untill a dept 18th 1984 d.Pa1tms,, t. zoeleiwoudeuwee p.o. bee O 2300MIelden the netho,Iande laboratory report 8414/35/O.N. 35.6.6731 T.N.O.-Apeldoorn Project-Fracture Mechanics Thsts

Welding Procedure Record

i Kryo i 31 110 2 Kz''oi 4 175 3 SW60/P240 4 4.75 30 d-39 SW60/P240 4 575 32 40 SW60/P240 4 475 30 41-58 8W60/P240 575 32 ,.ponno. 841172 C l'i - 'D 11

-39 , the weld has nun, at aide of layer

holl landse

con structi e

groep by

Dina. Amp. Volt.. R.O.L. speed Current

mm cm ónVmin.

50 50 50 5°

been gouched out

ac ac da/Ep dc/Ep dc/Ep dò/Ep

plate 70 mInt FeE 355 kT S.M.A..W. (manual) and S.A.W.

1G

120°C

.l5o °C

S.14.A.W. (manual) ElOotrode - KryO i

S.A.W. s Wire 'SW 60.'

stress relieved 'Flux - p '240

570-590°c/ISO' min.

Layer Electrode Wire/Flux

(30)

label 111g Welding procedure 70mm specimens 1:1L,Tcse.ries

Speo:imens 1.1LT'i9 = 11LT27

«derlis. ß'4M/35/O.N. 35.6.6731

cUt ?.N.O.-Apeldoorn

conimetee. proèct-Fracture. Mechanics Tests

iu*ct Welding Procedure Record.

leiden. _Oct c.nitel leboraleqi

-

'Teatsample t

-

WeldIng, process - Welding ponitiont - Preheat Xnterpass temp. i.

-

Filling materiali - llèattroatrnont joint preparation Ec -e r 18th 1984 nivel dspestmsn,1, plate 70 mm; FeE 355 )

S,.M.A..W. (manual) and S.A.'W.

1G,

120°C

15Ò°C

S.M.A.W. (manual)i Electròde

S. A.W. . t Wire

570-590°C/1:50 mifl.

hòIIandse

constrUctie

groepbv

lepOftilo. 841173 i1 E - 11F - Kryo I - SW 60 - P 240 layers as weldOd

-37 , the weld has been gouched out

'mm, at aide of layer i. Diam.

ma

Amp. Volt. R.O.L.

cm speed Current Vm1. 3 l'lO ac 4. 115 ac 4 . 475 .30 50 . ' dc/Ep 4 32 50 dc/Ep 4 47 30 50 dc/Ep.. .4 32 50 do/Ep I. Zootoiwoudseweg p.o. box G 2300 Mielden the nolheilande laboratory report Layer. Electrode wire/Flux i Kryol 2 Xryo.1 3 SW60/'P240 4-37 8W60/P240 38 8W60/P240 39-57' SW6O/P240

After welding lay untill a dept

(31)

Tabol IV

RESULTS OF 30mm SPECIMENS WELDMENT itT

Moment of fracture:

E - Fracture at final COD-teat.

I - Fracture at intermediate C0D'temt.

F - Fracture during-fatigue. 1LT7 .30 43888 6 0.16 0.07 0.10 22 0.20 0.12 0.13 44 1.49 E 4.04 4.54 9,74 1LT11 -30 48654 6 0.19 0.10 0.14 21 0.28 0.20 0.21 43B 164 E 0.26 0.22 0.18 ILT1 -40 37412 28 0.16 0.06 0.07 64.1 127 E >0.815>0.85 >1,09 1LT2- -40 45000 26 0.19 0.11 0.12 -44.5 138 E >0.51 >0.50 ->OE.52 1LTIO -40 41063 6 0.14 0.05 0.08 22 0.23 0.14 0.15 44.5 144 E 0.36 0.33 0.30 LLT3 50 50000 5 0 15 0 05 0 09 22 0.19 0.10 0.12 43.8 140. E 0.43 0.38 0.39 ILT9 -50 20157 6 0.15 0:05 0.09 8 0.19 0.10 0.13 29.6 210 I 0.22 0.13 0.15-1LT4 60 31843 19 0 20 0 11 0 14 35 6 113 I 0 17 0 08 0 09 1LT5 -70 16000 9 0.15 0.05 009 21.2 165 F 3229 (0.13) (0.04) (0.06) 1-LT8 -70 16825 12 0.15 0.06 009 27.7 160 F 3166 (0.13) (0.04) (0.07) 1LT6 -80 13463 7 0.15 0.05 0.09 24.8 181 F 3306 (0.13) (0.04) (0.07) Tábel V

-RESULTS 0F 30mm -SPECIMENS WELDHENT 21.2

SPECIMEN TEMPE. NUMBER NUMBER AVERAGE TNTCOD CRACK- LOAD MOMENT K C'FOD- AT PRACTUR

RATURE OF OF -COI) LKN(II AT AT (*

CYCLES TESTS FRACTURE FRACTURE FRACTURE

C r-1/3 RS hou, mm mm mm mm kil r-1/3 SS mm mm-Hou. mm 2LT16 -40 570O1 28 0.21 0.12 0.14 44.1 148 E >0.38 >0.35. >0.32 2LT17 -40 43934 27 -0.21 0.12 0.14 43.1 156 E 1.21 1.29 1.91 2LT23 -40 26522 -6 0.14 0.05 0.09 -6 0.19 0.09 0.12 7 0.28 0.20 0.21 36.0 188 I 0.24 0.16 0.17 2LT24 -40 35703 -6- O-15 0.06 0.10 - -6 0.19 0.10 0.1-3 --13 .0.27 0.19- 0.20- 41,8 161 1 0.23 017 0.15. 2LT-l4 -50 29150 16 0:25 0.15 0.19 32.6 212 E 0.29 0.20- -0.22 2LT22 -50 23615 6 0._15 0.06 0.10 -6 0.19- 0.09 0.13 -6 0.28 - 0.20 - 0.22 34.1 195-1 0.29 0.21 0.22 2LT13 -60. 43609 25 0.20 0.10 0h13 40.7 155 1 0.-19 -0.12 - 011 2LT-15 --60 27551 -17 0.22 0.12 0.16 30.9 220 I 0.22 0.12 0.15 21.T18 -70 29294 27 0.15 0.06 0.08 44.5 132 E 0.20 0,14 0.11 -2LT21 -70 28112 28 0.15 0.06 0.08- 44.9 132 E - 0.25 0.20 0.16 2LT25 -70 32300 28 0.3.6 -0.06 0.09 43.5 139 E 0.33 0.29 0.26 2LT19 -80 26333 28 0.15 0.06 0.08 6-3.9 1.36 E 0.20 0.14- - 0.1-1 21.220 -90 5695 0 - - 13.6 200 F 2556 (0.09) (0.01) (0.04)

SPECIMEN TEMPE- NUMBER NUMBER -AVERAGE INTCOD CRACK-: LOAD AT MOMENT K CTOD AT FRACTUP.

RATURE 0F OF COD LENGTH AT FRACTURE OF

CYCLES TESTS FRACTURE FRACTURE

r-1/3 liS loll. r-1/3 SS- hou.

(32)

8LT42 -30 42548 6 014. . 0.05 0.09 6 0.19 0.10 0.12 16 0.24 0.16 0.16 44..7 159 E 1.61 1.77 2.92 8LT43 -40 23028 6 . 0.15 0.06 0.09 6 0.19 0.10 0.13 3 0.28 0.19 0.21 31.5 215 I 0.27 0.18 0.20 8LT40 50 50401 25 0 20 0 11 0 12 43 2 150 I 0 20 0 14 0 11 8LT44 -50 29156 17 0.21 0.11 0.14 32.9 207 II 0.38 0.30 0.33 8LT45 60 24674 14 0 19 0 09 0 12 32 7 212 I 0 19 0 09 0 11 8LT41 70 31175 28 0 15 0 06 0 08 44 3 143 E 0 26 0 21 0 17 Moment of fracture:

E - Fractura mt final COD-teat.

t - Frn.-.turo intur,nedjnto COD-,:oui,.

Frneture during fmtigtio.

Tabal VI

RESULTS OF 3Omm SPECIMENS. WELDMENT 8LTa

SPECIMEN TEMPE- NUMBER NUMBER AVERAGE INTCOD CRACK- WAD MOMENT K CTOD AT FRACTUR RATURE OF OF COD LENGTH AT AT OF

CYCLES TESTS FRACTURE FRACTURE FRACTURE

C r-1/3 SS Hull, min min mm mm kM r-1/3 mm ES mm Noii. mm 8LT37 -20 28208 6 0.19 0.11 0.12 22.3 252 I (6270) 0.19 0.11 0.13 15 0.19 0.11 0.12 45.2 154 E 1.50 1.61 2.66 8LT28 30 9092 3 0 24 0 17 0 20 21 4 260 I 0 28 0 20 0 23 8LT29 -30 30278 26 0.21 0.12 0.13 46.7 130 E 0.25 0.22 0.16 8LT31 -30 20855 13 0.26 0.17 0,20 30.3 233 I 0,24 0.15 017 8LT32 -30 17288 7 0.24 0.15 0.19 22.2 260 I 0.24 0.15 0.18 8LT39 -30 11644 4 0.19 O,.1O 0.14 19.7 248 I 0.18 009 0.13. 8LT30 35 30919 20 0 21 0 12 0 15 35 5 178 I 0 18 0 09 0 10 8LT27 -40 5600 1 17.0 243 I 0.15 0.06 0.10 8LT33 -40 8101. 1 - 16.1 225 I 0.12 0.04 0.08 8LT34- -40 22620 8 . 0.15 0.05 0.09 7 0.19 0.10 0.12 30.9 193 I 0.17 0.08 0.10 8LT35 -50 18132 6 0.15 0.06. 0.09 5 0.20 0.10 . 0.13 27.2. 198 I 0.16 0.07 0.09 8LT36 60 48500 28 0 15 0 06 0 08 44 1 127 E 0 14 0 07 0 06 8LT38 -70 12300.8 . 0.15 0.06 0.10 22.6 187 F 3206 (0.11) (0.02) (0.05) Tabal VII

RESULTS. OF 30mm SPECIMENS WEU)NENT SLTb

SPECIMEN TEMPE- NUMBER NUMBER AVERAGE INTCOD CRACK- LOAD MOMENT K CTOD AT FRACTUR

RATURE 0F OF COD. LENGTH AT AT 0F

CYCLES TESTS. FRACTURE FRACTURE FRACTURE

- - - . r-1/3 SS Hou-. r-1/3 ss hou.

(33)

Tabel VIII

RESULTS OF 70mm SPECIMENS

Moment of fractura:

E - Fracture at final COD-teat.

I - Fracture at intermediate COD-teat.

F - Fracture during fatigue.

11LT15 -30 b 55865 6 0.20 0.09 0.15 6 0.30 0.19 0.24 6 0.38 0.29 0.34 62.7 650 E 0.56 0.49 0.60 ÏILT16 -30 b 42611 22 0.20 0.09 0.13 66.3 600 E >1.58 >1.66 >2.20 11LT22 .30 e 51151 6 - 0.20 0.09 0.14 6 0.30 0.19. 0.24 8 0.39 0.29 0.35 63.0 660- E 0.62 0.56 0.70 11LT12 -40 b 62326 5 0.19 0.08 0.14 .5 0.24 0.14 0.18 5 0.29 0.18 0.23 4 0.39 0.29 0.35 60.0 655 1 0.36. 0.26 0.30 11LT13 .40 b 39600 19 0.20 0.09 0.13 62.2 625 >0.95 >0.93 >1.32 11LT19 4O e 40723 6 0.20 .0.09 0.14 6 0.24 0.13 0.17 10 0.29 0.18 0.21 67;3 .550 E 0.82 0.81. 1.00 11LT2O 4O e 40256 6 0.19 0.08 0.14 6 0.29 0.18 0.23 7 0.39 0.29 0.36 61.0 630 I 0.27 0.16 . 11LT23 -40. o 53208 3 0.20 0.10 0.14 3 0.29 0.22. 0.24 5 0.38 0.32 .0.34 64.9 . 650 B 1.97 2.15 3.69 11LT27 -40 o 33203 . 3 0.20 0.09 0.15 3 0.30 0.19 0.24 2 0.39 0.29 0.35 53.2 675 .1 0.26 0.14 0.18 I1LT8 -50. a 32538 6 0.20 0.08 0.14 8 0.35. 0.24 0.30 51.0 785 B 0.36 0.25 0.31 11LT9 -50 a 16 . 0.19 0.08 0.13 60.2 645 E 0.65 0.59 0.76 11LT25 -50 o 30046 6 0.20 0.08 0.16 6 0.30 0.19 0.25 3 0.39 0.29 0.36. 51.5 730 I 0.28. 0.16 0.21 11LT2 .60 a 44722 21 0.24 0.12 0.17 66.3 559 E 0.50 . 0.43 0.52 11LT11 -60 . b 21332 6 0.20 . 0.08 0.i4 5 0.35 0.24 0.31. 42.8 893 .1 0.34 0.23 0.29 11LT21 -60 o 46827 6 0.20. 0.07 0.14 -16 0.29 0.16 0.23 67.8 545 E 0.35 0.25 0.29 11LT24 .60 c 51130 .3 0.19 0.08 0.14 -9 0.30 0.19 0.24 69..9 510 E 0.32 0.23 0.25 11LT26 -60 c 39632 3 0.20 0.09 0.15 IILT6 -70 a 35678 17 0.23 0.12 0.16 67.6 517 E 0.24 0.14 0.15 11LT17 -70 b 32008 . 19 0.19 0.08 0.12 65.9 515 E 0.25 0.14 0.16 t1LTI8 -70 b. 13656 6 O19 0.08 0.13 35.8 713 F (4019) -1ILT4 -80 a 10438 4 0.19 0.07 0.14 30.]. 787 F (0.17) (0.06) (0.11) 11LT5. -80 a 12 0.19 0.08 0.13 49.5 790 E 0.33 0.21 0.27 1ILT14 -80 b 30487 4 0.20 008 0.15 12 0.25 0.13 0.18 57.0 655 ¡ .0.25 0.12 0.17. 1ILT1O -90 b 2616 0 17.5 850 F 3015 1ILT7 -100 a 3800 . 0 19.4 850 F 3166

SPECIMEN TEMPE WELD NUMBER NUMBER AVERAGE INTCOD CRACK- LOAD AT MOMENT K CTOD AT FRACL'UR

RATURE MENT OF 0F COD- LENGTH AT FRACTURE OF

CYCLES TESTS FRACTURE FRACTURE

r-1/3 ES Holst r-1/3 ES Holst

(34)

o. 750 700 -60o. MPc 550- 500- 50- 400-j I- - I--150 -100 -50 0 .50

I c

fig. 1 Yie].,d strength an-d ultimate tensIle strength of we:1d rnàt-erial

(35)

ob

(36)

071

fig.3

Geometry oP 70mm specimen.

w C w E o EI-w-J D.. mc o L." wo EL

'-I

zo

(37)

fig.4 Indication of orientation for epecimens- taken out from platee.

S.w nil noti

fig.S Instrumentation of' fabalt-teet specimen.

I

(38)

f12.6a lest eqwipment for testIng 30mm specImens.

t4

fig.6b Test equipment foi' tesLing 70mm specimens.

e

I

(39)

fig.?

10 20 30 40 50

CRACKLENGTIH a mmi

Maximum load and stress intermsity faötor (K) during fatigue

for fabalt spec:imeriS, based on reachIng, the yield stress at

the cracktiP wt:h a Unear stress distribution over the

(40)

fig.8 _{Calculation of COD c:racktip value} _{èsûming a p]ast'i':c. hinge.} loo -90 80 -7o 60 50

-:40

I-ru Q. 'J 4-'n IQ 20 io O pø5Iic binge o CT.O.OE(mm)

(41)

TH De Ift

TEST DATA: _n n n cyclea e61 fa mm mm 8510 9460 10298 11270 12296 13073 13996 14888 15777 16660 17533 18595 19473 20495 21491 22540 24389 25408 26679 28145 28173 30927 32370 34005 35703 33 35.50 34 36.71 35 37.71 36 38.77 37 39.83 38 60.84 39 41.83 COD C0D.5 0.25 0.27 0.27 0.29 0.30 0.30 0.40 0.42 0.43 0.44 0.45 0.47 0.69 0.72 0.73 0.75 0.77 0.80 0.82 0.85 0.88 0.89 0.91 0.95 0.86 mum min 0.06 0.08 0.09 0.10 0.12 0.12 0.19 0.21 0.23 0.24 0.25 0.27 0.44 0.48 0.50 0.53 0.56 0.61 0.64 0.69 0.73 0.78 0.83 0.91 0.85 SPECIMEN PARTICULARS: REMARKS:

Fracture at intermediate COD-test.

fi.9a

Tesl data of specimen 2LT24 from /13/.

200 234 208 0.1.5 0.06 0.10 237 202 0.16 0.07 0.11 231 197 0.15 0.06 0.10 225 191 0.15 0.07 0.10 219 186 0.15 0.06 0.10 212 181. 0.15 0.06 0.09 226 175 0.19 0.10 0.13 225 170 0.20 0.10 0.13 222 165 0.19 0.10 0.13 217 1.0 0.19 0.10 0.13 214 155 0.19 0.09 0.12 207 1.51 0.19 0.10 0.12 208 166 0.28 0.19 0.21 205 141 0.28 0.19 0.21. 203 132 0.27 019 021 200 132 0.27 0.19 0.21 195 128 0.27 0.19 0.20 191 123 0.27 0.19 0.20 187 119 0.27 0.19 0.20 182 115 0.27 0.20 0.19 178 111 0.27 0.20 0.19 174 107 0.26 0.20 0.19 170 103 0.26 0.20 0.18 1.66 99 0.26 0.20 0.18 161 0 0.23 0.17 0.15

p p CTOD CTOD CTOD

Illax min 1/3R BS Hou. kN kN tam sum mia

SPEC IMEN: 2 LT 2 4 DATE: 21-11-85 TEMP.: -40 C 29.5 mm 90. mm 150 mm 569 N/mm2 1.6 mm 18.5 mm 0.3 4 Hz B: W: S: si gma - y: z: R: freq: 15 16 17 18 19 20 21. 22 23 24 25 26 27 28 29 30 31. 32 10.00 15.51 16.68 17.72 18.86 20.54 21.53 22.60 23.67 24.77 25.86 26.91 28.06 29.09 30.16 31.11 31.92 33.34 34.35

(42)

C. T o D 0.2

H

CTOD-CURVZ 5PECtl1EN NR. 2L724

n---C.rsklongth LmIJ

fi.9b 'ETOO curve of specimen 2LT'24 from /3/.

/

r

. 1 I' i! I, I.IR 89

fig.9ò Load curve o-F' specimen 2LT24 from /13/.

LORD SCOiJENCE OF SPECZÑEÑ NR 2LT24

240 230 -220 2*8 280. *90 180 ¡10 lee -ISO P *40 -¡38 k ¡20 IJIO -laß- w9e -80... 10 -Ge 40 ,30_ 20 10 e S IO IS 20 29 30 39 4e 45, CrckIngh LJ

(43)

TH Deift

1iLT.22

TEST DATA:

REMARKS:

Fracture at end COD-test.

n a a COD COD-S cycles est Es mm mm mm mm 0.07 0.09 0.11 0.12 0.15 0.16 0.32 0.34 0.37 0.40 0.43 0.47 0.54 0.60 0.84 0.92 0.84. 1.14 0.7,7 0.00

fig.lOa Tcst dat1

of specimen 11LT22 from :113/.

.10.0 6712 22 23.1 0.33 8227 26 25.2 0.34 9625 26 26.9 0.35 11205 28 29.0 0.37 13204 30 31.2 0.38 14562 32 33.0 0.40 16479 34 35.4 0.62 17628 36 36.9 0.64 19057 38 38.3 0.66 21378 40 40.4 0.69 24385 42 43.2 0.71 26019 44 611.9 0.75 28188 46 66.6 1.03 31167 48 49.1 1.07 36036. 50 51.4 1.12 36880 52 53.6 1.15 60290 54 56.1 1.16 43510 56 58.2 1.25 67167 58 604 1.30 51151 60 63.0 2.19 1' max kN P min kN 850 CTOD l/3R ,mn CTOD RS mm CTOD Hou. mm 924 782 0.20 0.07 0.15 918 '55 0.20 0.08 0.15 897 729 0.20 0.08 0.14 872 703 0.20 0.09 0.14 831 678 0.20 0.09 0.14 808 653 0.20 0.09 0.14 890 629 0.30 0.19 0.24 895 605 0.30 0.19 0.24 893 581 0.30 0.20 0.25 868 558 0.30 0.19 0.24 836 536 0.29 0.19 0.24 820 513 0.30 0.19 0.24 803 492 0.40 0.30 0.37 780 471 0.40 0.30 0.36 753 450 0.39 0.29 0.36 731 430 0.39 0.29 0.35 703 410 0.37 0.27 0.32 681 391 0.39 0.29 0.34 660 372 0.38 0.29 0.34 660 0 0.62 0.56 0.70 SPECIMEN: 11LT22 DATE: 16-8-85 TEMP.: -30 SPECIMEN PARTICULARS: B: 6.9.4 mm W: 140.4 mm S: 210 mm sigma-y: 523 N/min2 z: 3 mm 24 min R: 0.3

freq:

4 Hz

(44)

n

0.8 L? 0.8 -LS C 0.4_ n 0.3 0.2 0. I

-

/r-ii

/

/r

/

e , , I I I I t I $ t I

I'll

I I I 23.125.220.8 29 31.2 33 3!'3ø.930.a'0.4'3.2'4.94G.G49.ISl.453.65G.l90.2BB.4 83 CraokIin9t,h Lm.ni

f.ig.iObcTOD curve of specimen i.1,L122 from /13/.

I 3R

-.-H1ea.

flg.lOc Load curve of specimen 11LT2,2 from

/13/.

950 900 eso 800...

LORD SEQUENOE or 0PCDIEN NR. I 1LT22

+ ?S0... 60e... 550ì P 500... k N 458:_ 400 380 300... 250 200 150... 106 50 '0

-IO 20 30 40

CtIoNjitLiiJ

50

(45)

Li 0,6 0,5-0,2 0,1 0.6-0,5 0,4 A V O ILl A V O ZLI

&! 4waIdaaa eucj

I I ftt,,r. th,ri.Q Iatíua-t,st LfIU at C 00-tilt Laa,raq. valuai of m$,r.adat. (700 -0° E E0,3 Ò Ò -0,1 O -80° A V i.,td.nt IILT..1 A V O oildau _lILr-bL A V O O witd.il,t lILT-c I

'-L

L---J 1__,_J

L---J L_---J L_---J

I liest tempI -70° -60° -50° -40° -35° -30°

-Pig.11a Overview of 30mm fabalt test results, ClOD calculation based on r1/3.. 'fractura dormO -faIqu.-t.it frituri it C 00-t.,, avurig. va4uo of mtorm.dlatu (TOO QOZ 065e _>O95Ô 4.04 _ô1615 _è1503 >133 1.9 L__r_J L__.__J L_ L ---:Test temp.(°C1 -70° -60° -5O -40° -30° -20°

fig.11b Overview of 70mm fabalt test results, _{ClOD calculation}

(46)

rP (n rP (D U) C rP u) C)

4 o

o

C)

O'.

I

o _C a' o U 0,2 ZO tri _900

80°

'7,' 45b

.'

*,

¡

L__T__J

7ö°

-oo° 500 Test temperature (°C)

L---_350

30°

N O. D

oc

orn Q.J. 0,5

V Q

A V

O wetdrnent 1lT

]

O wetdrnent 2LT wetdment 8LT4I i

i J

'fracture during s., I I I go o I fatigue-test. i at C.0 -test

rr4

o L average valijas o interñiediate c.to.a

wo

Cfl3 0,4 >0.829 1.268 4,51

(47)

-b I-a. 0.6, OC

orn.

I-w

I' o

rrb

D. cn3

3.

n w V. 'J,,, r D I-

I

,O1O

I-I-100C) nAo I-. 7V Û. o

A V 9

weidment 11LT-a'

A V O

wetdment 11LT-b1

AV Q

Owetdment i1LTcJ I I fracture during I I fatigue-test. at C.a-fest

'average ,vatues of intermediate C.tD.D.

V

13 a 9 25 12 L_,_J

L_.rJ

L_J

7O0

.

6O 5Ø0

-40°

.

Test temperature (°t)

>.0.93

1

0.81 2i5 4 L..,_J

L---J

(48)

-I, t-' QQ (J, O (D rlW 'l (DQQ ' ((D (A (n tDt-' (no Pt-.. (D

-.

E

St)

E

5th

-

d

Li ('(D

3m

CAZ I- rr C-) -4 o o (D C ID (A 2,2- 1,2 1,0 _0,8 _{0,6 -} _{0.4 -} 0,2 o -100 -80° -70° -60°

5°

-40° -30° L20° Test temperature ('C) 2.2 _o O weIdmenf I LT ie(dmenf 2 LT wewrnent 8 momenP of fracture:: F 3 A16 25 64b io &lb

Oi4O''

21

-9l

AOb

Oi

_42b

lest temperature (T) 30mm specimen. (B30rnrn ; W = 90mm)

37a

37a -100°

-'i'

-80° -k.. 60° -50° -'p° -30° -20° _10°

(49)

2,2-QQ

eicLx;O;i3:16;19en23

---ecL.:.;13:16;19en23

-.

-br- OiD orn rl- Ql

m'i

D 1,6

Ô.,

flED U) UI cno -D -.4,'--1,2 -Jul

o

30

-E1.0 cnO E -Oc

-

w'--q

o. D rl-0,6

o

2,0 -o -4

-J.

ç:i

o

P 3 3 '-Joe U) Ql o p.,. 3 ID D U) û al I-' o C I-. a' rl- Ql o- al o C, w (n 2.2

weidment liLT-a wetdment il LT -.b

2.0 0 weWme't 1ILT#c niornèñt of fracture: F i .8 1,6 _0,6 _0.4 _0.2 _o

è3

13

0'9

16

.9.

0

01511 O2411

Ofl"

176

026° 025" 2O O' -10 e -100° -90° -80° _700 -60° _500 -40° -Test temperature ('C) 70mm specimens (B=lOmm W=140mm) rl-O i i i i I I i I I -10O° -90' 80° 70° -60° -50° 400 -30° . _200 100 0° Test temperature ('C)

(50)

E E

o

_ci 2,2 2.0 1.8 1,6 1.4 1,2. 1.0 _0,8 _0!6 .4 _0.2 30mm specimen British Sandertd 70mm specimen 30mm specimen

==

7Omm specirneñ r-1/3 o _{100° -90°} -80°

-7o° -°

4Q0

3°

Test temperatijre 1°C) 20° _100 -4, I-J. 2,2- 2,0 _.1.8 OD '-'-O.

3"

ml-'

i

wO o -I, 1,4 I- (D 1,2 (D QQ ,

E1

E U)

-U) ' ci

o.

LI 0,8 06 UI O -4, 0,4 3 o. 0,2 o. D 3 3 -30mm specimen British Stnderd .70mm specimen

o---t

i-i I I t 1000 -50° -80° -70° _600 50° _400 -30° _200 -10° 'Test temperature (°C)

(51)

1ß 0,9 0,8 0, E; E , 0,6

tJ.

4. Q3: 0,2 1/3_7 HOLLSTEIN IlL! 30mm. 8/W.0,33 1 Z:3.1

4,4,

<V .', British Standard 70mm.

f.. '

B/W5.

f,',,

J,

dr,

ritish Standard P30mm 8/W! 0.33 Ql 0,2.. 0,3 0,4 0,5 0,6 0.7 . . 0,8 0,9 C.T.OED.J. r= l/3(mm)