Investigations into the strength of automatically made welds containing notches, Summary of testing program to be presented at the Kyoto-Collquium, 1969

LABORATORIUM VOOR

SCH EEPSCONSTRUCTIES

TECHNISCHE HOGESCHOOL

-

11W-doc. TC-910-17-68.

RAPPORT Nr.

SSL 137

BETREFFENDE,:

Investigations into the strength of automatically made welds

containing notches.

W.P. van den Blink, R. Dechaene,

SSL 137

TC-910-17-68

Investiations into the strenth of automaticall made welds

containing_notches.

Summary of testing program to be presented at the Kyoto-colloqulum

_1969.

The strength of welds depends to a large extent on the number, size and orientation of defects. When brittle fracture is concerned it is probable that the quality of the material at these defects is at least a important

as the mentioned geometrical factors.

One possible cause of damage is the mechanical and thermal treatment exert-ed on the material at a notch in an existing weld when a new weld is made close to the former one. This situation particularly occurs at weld- cross-ings and where stiffeners pass over butt welds. The unfavourale effects of straining notched material, particularly when this occurs at temperatures

botween 200 and LfOO°C, are weil, realized today.

One original point of the present investigation is that these effects are studied for weld-mtai. For comparison similar specimens are included in which the notches are made after Welding. The study of casualties has shown

that weld metal which has not been embrittled is in general not prone to brittle fracture.

It is thought that the most attractive welding methods to be considered in this respect are automatic methids with one or a limited number of runs. in the.first place the general quality of these welds as determined by conventional acceptance tests is a point of discussion. In the second place these methods are very attractive from an economii'point of view.

The program comprises two steels with yield points respectively above and below the yield point of the weld metal. The reason is that a difference in yield point between weld metal and base metal strongly influences the overall and the local deformations in case of notched transverse welds, while little effect is expected in notched longitudinal welds. The pract-ical importance of this point fully justifies an experimental verification.

Tensile tests will be performed on plate-specimens 1000 x 500 x 25 mm each containing two or three weld-crossings and the same number rf notches.

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