Numerical and experimental analysis of electric conductive heating for micro warm coining of stainless steel

The aim of this study was to investigate the electric conductive heating of stainless steel, which is the initial step in the research of micro warm coining of high strength metals. This paper presents the numerical and experimental analysis of the electric conductive heating under variation of heating time, electric current and heating atmosphere. The material used was stainless steel X5CrNiMo17-12-2 (1.4401). The geometry of the samples was 100 × 50 mm² with an initial thickness of 1 mm. A 3D coupled thermal-electrical model in Abaqus/Standard was used to help analyzing the heating process. The results of FEM simulation show that using 1,600 A electric current within 5 s conductive heating could give a uniform temperature distribution area of 20 mm × 20 mm as the micro warm coining zone at a temperature around 900°C. The simulation was confirmed by experimental results showing a similar temperature distribution, heating rate and cooling rate. Heating under vacuum increased the maximum temperature slightly as compared to heating under argon or air during the electric conductive heating. Closed die micro warm coining with integrated electric conductive heating of stainless steel has been successfully realized.