EVALUATION OF SOME INDIGENOUS M.S. ELECTRODES FOR THEIR SUSCEPTIBILITY TO HOT CRACKING USING DOUBLE FILLET WELD TEST

Abstract

The double-fillet test has been developed from the T-test and is more severe than its predecessor. to the form prescribed the test has been found useful for research purposes, both for the grading of electrodes and for testing a given plate/electrode combindations. The t major developments from the old T-test are, firstly, that the two welds, the restraining weld and the test weld, are laid alnost simultaneously, and secondly that the width of the top-member has been increased. For the purpose of classification, three levels of severity are used, corresponding to widths of the top-member i.e. 1 in., 1 2 in. and 2 in. It is suggested that an electrode which produces weld cracking with all the three severity levels should be rejected in practice. Two further modifications have been made. . Firstly the restraining weld is made with an austenitic electrode. This enhances the severity of the test, due to the greater coeffi-cient of thermal contraction. Secondly, the underside of the top-member is chamfered to give a standard degree of penetration. Investigations on the factors affecting hot cracking are 0 carried out. Weld metal analysis revealed that hot cracking is very sensitive to sulphur content. The general superiority of . low-hydrogen electrodes has been observed.