Microstructure and Hardness of ZG3Cr13 Steel After Long Time Ageing Between 550℃～600℃

The microstructure and hardness of ZG3Cr13 heat resistant steel after 2500h aging between 550℃～600℃ were studied.The results showed that the hardness decreased obviously during 1000h aging,then the hardness tended to be stable.The change of microstructure is related to the microstructure homogeneity after normal heat treatment.The more uniform distribution of the original microstructure,the higher stability of microstructure and higher heat resistance after aging.