The Effect of Heat Treatment Process Parameters on Mechanical Properties, Precipitation, Fatigue Life, and Fracture Mode of an Austenitic Mn Hadfield Steel

In this study, the effect of cooling rate after heat treatment on mechanical properties, fatigue life, precipitation and fracture mode of an austenitic Mn Hadfield steel was investigated. Cast samples of the Hadfield steel were heat treated at 1100C for 2h. The samples were subsequently quenched in pure water and also in 3wt.% NaCl salt bath. Optical microscope (OM) and scanning electron microscope (SEM) were used to analyze microstructure andfracture surfaces. Transmission electron microscope (TEM) was used to assess the precipitates. X-ray diffraction (XRD) was used to determine the phases formed. Mechanical properties and fatigue life were determined by uniaxial tensile test, bending fatigue and hardness measurements. Results showed that the sample quenched in salt bath had lower Mn3C precipitates, hardness, yield and tensile strengths. Instead, this situation resulted in a more ductile fracture mode and higher formability. Finally, the fatigue life of the sample quenched in salt bath was longer than the one quenched in pure water.