Multi objective optimization of cold crack susceptibility of high strength low alloy steel 950A using Grey Relational Analysis

Abstract

Cold cracking is one of the problems associated with joining of high strength low alloy steels. The selection of optimum parameters for welding process decides the properties and joint integrity of the welds. The effects of process parameters on cold cracking susceptibility of HSLA 950A has been studied. Heat input, temperature of preheating and oxide particles content are taken as input parameters. Impact strength and cracking percentage are taken as responses. In this work, the multi objective optimisation has been attempted using Grey Relational Analysis to optimize process parameters for controversial responses. The recommended parameter levels for the high grey relation grade has been determined. Heat input, preheating temperature and oxide particles that are added to the weld have equal contribution to the impact strength. The oxide particles that are added to the weld also an influence on the hydrogen induced cold cracking resistance of the HSLA 950A weld metal. Percentage increase in Grey Relational Grade is about 75%. The results of the model have been checked by conducting the confirmation experiment. The result lies within the acceptable level of confidence interval.