Multi-objective optimization of FCA welding process: trade-off between welding cost and penetration under hardness limitation

Abstract

Flux-cored arc welding (FCAW) is an innovative semi-automatic assembly process that is increasingly used in the industrial sector. However, the achievement of quality welds on steels with a low weldability index often and inevitably rhymes with high production costs. Therefore, the optimization of welding conditions in order to find a compromise between economic and technological criteria is of great interest. This document proposes the determination of optimal welding parameters, which minimize the total welding cost and maximize weld penetration simultaneously under maximum allowable hardness limitation in the heat-affected zone (HAZ) of high-strength low alloy steel (HSLA) grade S460. The decision variables chosen are welding current, welding speed, voltage and preheating temperature. For this purpose, a mathematical model of the total welding cost for the FCAW process has been developed. Then, the optimization problem is implemented with Matlab™ software and solved using a non-dominated sorting genetic algorithm (NSGA-II). The near optimal solutions are presented as a Pareto front. The choice of optimal welding parameters according to the operator’s objective is made simple and practical. The study highlighted the major role of preheating in reducing the total welding cost and preserving the quality of the weld joint for HSLA steel.