关键词: 26CrMo4钢, 淬火, 回火, 组织, 拉伸性能, 冲击性能

Abstract: Phase transformation temperature of 26CrMo4 steel was tested by using Gleeble-1500 thermal simulator, and then the steel was water quenched at 910 ℃ and tempered at 400-740 ℃. The microstructure and mechnical properties of the as-rolled as well as the quenched and tempered 26CrMo4 steel were tested by means of OM, tensile test, hardness test and impact test. The results indicate that the 26CrMo4 steel has very good hardenability, and can obtain martensite microstructure with fine and uniform prior austenite grain by water quenching at 910 ℃. The strength and hardness of the steel decrease as the tempering temperature increases, and the decrease rate for the tensile strength are 1.685, 1.500 and 2.822 MPa/℃ respectively when tempered at 400-600 ℃, 600-640 ℃ and 640-730 ℃. The impact property of the steel increases as the tempering temperature increases. The impact absorbed energy at 0 ℃ reaches the maximum value of 227 J when tempering at 700 ℃ and then remains almost unchanged when tempering temperature further increases to 730 ℃. In addition, the 26CrMo4 steel has very good cryogenic impact properties when tempered at 640 ℃ and 700 ℃, where the -70 ℃ impact absorbed energy are 81 J and 110 J, respectively.

Key words: 26CrMo4 steel, quenching, tempering, microstructure, tensile properties, impact properties