Multi-Objective Optimization of HAZ Characteristics for Submerged Arc Welding of Micro-Alloyed High Strength Pipeline Steel using GRA-PCA Approach

Abstract

AbstractIn any type of welding, its heat affected zone (HAZ) is the most critical section where the probability of hydrogen or solidification cracking is prominent. Continuous efforts are being applied by researchers and welders to minimize HAZ and its alterations. For the same purpose, by varying the factors of submerged arc welding (SAW) process which directly influences the heat input and cooling rate of the weld, experiments are carried out on the plates of micro-alloyed high strength pipeline steel. Voltage, welding speed, contact tube to work distance, wire feed rate and preheating temperature are taken as process variables. The experiments are designed according to the central composite rotatable design approach of response surface methodology (RSM). Multi-objective optimization of HAZ characteristics (HAZ area and its hardness) is carried out using grey relational analysis (GRA). To un-correlate the correlated characteristics of HAZ, principal component analysis (PCA) approach is coupled with GRA. The results of the confirmatory test have shown an improvement of 28.51 % and 5.94 % in area and hardness value of HAZ respectively at optimal setting combination of SAW process parameters.