the effect of tempering treatment on the microstructure and mechanical properties of din 1.4021 martensitic stainless steel

to investigate the effect of tempering treatment on mechanical properties and the microstructure ofdin 1.4021 martensitic stainless steel, austenite treatment was conducted for the samples at 1000ºc temperature for 60 min and then the samples were oil quenched. later, tempering treatments wereperformed for the samples at 500 ºc and 700 ºc temperatures for 2 and 5 h, respectively; then quenchingin oil was conducted. after the heat treatment, hardness, tensile strength and impact tests were performedto investigate mechanical properties. moreover, optical microscopy and field emission scanning electronmicroscopy (fesem) were performed to investigate microstructure observations and fracture surfaces.x-ray diffraction (xrd) was carried out to measure the austenite retained in the samples. the resultsshowed that due to the formation and precipitation of alloy carbides cr7c3, the tempering treatment at atemperature of 500 ºc increases hardness, tensile strength and yield strength and reduces the amount ofimpact energy of the samples as well.