Mechanical Properties and Microstructure of TIG and ATIG Welded 316L Austenitic Stainless Steel with Multi-Components Flux Optimization Using Mixing Design Method and Particle Swarm Optimization (PSO)

Abdeljlil Chihaoui Hedhibi; Kamel Touileb; Rachid Djoudjou; Abousoufiane Ouis; Hussein Alrobei; Mohamed M Z Ahmed

doi:10.3390/ma14237139

Mechanical Properties and Microstructure of TIG and ATIG Welded 316L Austenitic Stainless Steel with Multi-Components Flux Optimization Using Mixing Design Method and Particle Swarm Optimization (PSO)

Materials (Basel). 2021 Nov 24;14(23):7139. doi: 10.3390/ma14237139.

Authors

Abdeljlil Chihaoui Hedhibi^{1

2}, Kamel Touileb², Rachid Djoudjou², Abousoufiane Ouis², Hussein Alrobei², Mohamed M Z Ahmed^{2

3}

Affiliations

¹ Department of Mechanical Engineering, National Engineering School of Tunis (ENIT), El-Manar University, P.O. Box 37, Belvedere Tunis, Tunis 1002, Tunisia.
² Department of Mechanical Engineering, College of Engineering in Al-Kharj, Prince Sattam bin Abdulaziz University, P.O. Box 655, Al-Kharj 16273, Saudi Arabia.
³ Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering, Suez University, Suez 43512, Egypt.

Abstract

In this study, the effects of pseudo-ternary oxides on mechanical properties and microstructure of 316L stainless steel tungsten inert gas (TIG) and activating tungsten inert gas (ATIG) welded joints were investigated. The novelty in this work is introducing a metaheuristic technique called the particle swarm optimization (PSO) method to develop a mathematical model of the ultimate tensile strength (UTS) in terms of proportions of oxides flux. A constrained optimization algorithm available in Matlab 2020 optimization toolbox is used to find the optimal percentages of the selected powders that provide the maximum UTS. The study indicates that the optimal composition of flux was: 32% Cr₂O₃, 43% ZrO₂, 8% Si₂O, and 17% CaF₂. The UTS was 571 MPa for conventional TIG weld and rose to 600 MPa for the optimal ATIG flux. The obtained result of hardness for the optimal ATIG was 176 HV against 175 HV for conventional TIG weld. The energy absorbed in the weld zone during the impact test was 267 J/cm² for the optimal ATIG weld and slightly higher than that of conventional TIG weld 256 J/cm². Fracture surface examined by scanning electron microscope (SEM) shows ductile fracture for ATIG weld with small and multiple dimples in comparison for TIG weld. Moreover, the depth of optimized flux is greater than that of TIG weld by two times. The ratio D/W was improved by 3.13 times. Energy dispersive spectroscopy (EDS) analysis shows traces of the sulfur element in the TIG weld zone.

Keywords: 316L SS; ATIG welding; mathematical modeling; mechanical properties; microstructure; mixing design method; particle swarm optimization (PSO); pseudo-ternary flux.