Abstract: Microstructure and properties of 12Cr steel after different heat treatment were investigated by using OM, tensile test, hardness and impact test at room temperature. The results show that the quenching temperature has a significant effect on the grain size of the 12Cr steel.The grain size of the 12Cr steel gradually grows with the quenching temperature increasing, while the impact property is improved and the hardness is increased significantly. The strength of the 12Cr steel is decreased gradually with tempering temperature increasing. When the quenching temperature rises to 1160 ℃, the grain size is up to 3 grade, when the tempering temperature exceeds 700 ℃, the short-term rupture property of the steel is significantly worse. When quenched at 1100 ℃ and tempered at 680 ℃, the microstructure of the 12Cr steel is tempered lath martensite, and the short-term rupture property is optimal.

Key words: 12Cr steel, microstructure, mechanical properties, short-term rupture property