Softening annealing process of GCr15 bearing steel

The GCr15 bearing steel was annealed at 550-900℃, and its microstructure was observed.The hardness was tested, and the annealing and decarburization transformation mechanisms were analyzed and discussed. The results show that the microstructure and hot rolling state of GCr15 bearing steel annealed at 550℃ had not changed basically. When annealed at 600-750℃, with the increase of temperature, the lamellar spacing of fine lamellar pearlite gradually increased, and the fine lamellar pearlite basically disappeared at 750℃, which was mainly composed of spheroidized carbide particles and strip carbide particles. When annealed at 760-800℃, the microstructure gradually tended to complete globalization with the increase of temperature. When annealed at 850-900℃, the coarse lamellar pearlite gradually increased with the increase of temperature. When annealed at 550-900℃, the hardness first decreased and then increased. When annealed at 750-900℃, the hardness was less than 245 HBW, which met the standard requirements.