Abstract：1E1158M steel developed by Caterpillar is used for track pin and the final heat treatment is quenching and tempering. However, the inherent grain size appears mixed crystal after final heat treatment, which affects the performance. In this paper, the thermal simulation test and the quantitative analysis of microstructure were carried out to investigate the mixed crystal phenomenon of inherent grain size of 1E1158M steel under different finishing temperatures. The results show that the abnormal grain growth temperature of hot-rolled and normal-fired microstructures is both 850°C, and the finishing rolling temperature has an effect on mixed crystal degree. When the finish rolling temperature is 850°C, the austenite grains are partially recrystallized at the end of rolling, and the degree of mixed crystals is serious. As the finishing temperature increases, the inhomogeneity of the intrinsic grain size decreases and the recommended finishing temperature is 1000°C.
2020, Vol. 55 
