Funct. Mater. 2023; 30 (2): 212-216.

doi:https://doi.org/10.15407/fm30.02.212

Effect of heating temperature and holding time on microstructure and mechanical properties of quenched GCr15 bearing steel

Guiyan Ye, Yujun Li

School of Materials Science and Engineering, Jiujiang University, 332005 Jiujiang, China

Abstract: 

The effects of heating temperature and holding time on the quenching microstructure and hardness of bearing steel GCr15 were studied by means of optical microscopy (OM), scanning electron microscopy (SEM) and hardness testing. The results show that when GCr15 steel is quenched between Ac1 + (30-50°C), the microstructure obtained by the metallographic method consists of acicular martensite + undissolved carbides + residual austenite. The longer the holding time, the thicker the martensite sheet, the less undissolved carbide and the more residual austenite. The hardness decreases with increasing holding time. When the heating temperature is lower than Accm, the microstructure of GCr15 steel after quenching consists of acicular martensite + undissolved carbide + residual austenite; the acicular martensite becomes coarser and the hardness increases with increasing temperature of heating. When the heating temperature is higher than Accm, the microstructure of GCr15 steel after quenching is acicular martensite + residual austenite, and the amount of residual austenite increases with increasing temperature, while the hardness decreases.

Keywords: 
GCr15 steel, quenching, acicular martensite, hardness, residual austenite, undissolved carbides.

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