Analysis of the mechanical performance of spot welding on PHS 22MnB5 steel

Abstract

The hot pressing hardened steel known as “press hardened steel - PHS” is a steel of extreme importance for the automotive industry. The application of this type of steel in the structure of vehicles promotes the improvement of safety, mass reduction and lower fuel consumption. The increase in the use of this type of steel, culminated in the need to deepen knowledge about the joining processes, more specifically about the electrical resistance spot welding process - RSW, which is one of the most used processes in automotive structural construction. The aim of the present work was the evaluation of the autogenous spot weld of 22MnB5 steel hardened through heat treatment in laboratory scale, simulating the cooling rates used during the hot pressing, commonly used in the automotive industrial practice. Welds were made in two different conditions, with welding parameters in a single step (direct welding) and with parameters considering additional pre and post heating steps. Mechanically, the welds were evaluated through the standardized test called tension shear test. The results showed that, according to the American Welding Society - AWS standard, the performance of the welds meets the minimum requirements required for the group of materials in which 22MnB5 falls.