Application of FEM simulation method in area of the dynamics of cooling AHSS steel with a complex hybrid welding process

Abstract

The purpose of this paper is to present the course of a thermal cycle induced by welding in characteristic points in a joint and demonstrate the capabilities of simulation techniques with regard to thermal analysis of welding. Hybrid plasma-arc welding (HPAW) tests were conducted on samples of advanced high-strength steel (AHSS). Welding FEM analysis was carried out. Cooling time was determined for characteristic zones in the joint. The results of the simulation were then juxtaposed with the experimental data. Considerable diversification of the t8/5 and t8/3 times was observed for the analysed areas in the joint. The description of the thermal cycle presented in this paper questions the validity of analysing the changes occurring in the HAZ with the use of conventional TTT diagrams, extending the analysis of thermal conditions of a produced joint by new techniques of numerical prediction of thermal history of HPAW.