Influence of Weldmatching on Mechanical Behaviours

Abstract

Different tests were carried out on the butt joints of several kinds of steels to study the effects of weldmatching on the fracture or strength, and fatigue behaviour of welded constructions. The effects of weldmatching on the strength of welded structures were investigated and appraised directly by experiments in accordance with the general yielding criterion based upon “Fitness for Purpose” philosophy. The test results show that overmatching of weld metal increases the possibility of having a general yielding and may help tolerate larger weld defects, and certain factors, such as strain ageing and heat treatment can change the degrees of weldmatching, thus affect acr. It is obvious from test results that great care must be taken, when the safety against fracture initiation of welded joints with different weldmatching is evaluated solely based on COD concept. Effect of weldmatching on the fatigue behaviour was appraised based upon four point bending test data of two kinds of welded joints. To analyse crack growth the fracture mechanics approach was used. Although the values of ΔK th are equal in the two kinds of welded joints, the fatigue crack propagation rate da / dN for A 131 steel welded joint was faster than that for A537 welded joint.