不同淬火方式对KMN钢组织及力学性能的影响

Effect of Different Quenching Way on Microstructure and Mechanical Properties of KMN Steel

真空气淬相较于传统热处理工艺具有控温精度高,表面氧化脱碳少等优势,但同时具有冷却速度慢的劣势。本文对KMN钢锻件进行真空加热970℃、淬火(5 bar氮气冷却或油淬)及580℃高温回火。热处理后,检验其力学性能和显微组织。结果表明:经气淬并高温回火的KMN钢力学性能略低于油淬并高温回火,显微组织均以回火索氏体为主。KMN钢经真空气淬或油淬并高温回火后,可以得到类似的力学性能与显微组织。

Compared with the traditional heat treatment process, the vacuum air quenching has the advantages of high temperature control precision, less surface oxidation and decarburization, but also has the disadvantage of slow cooling speed. In this paper, KMN steel forgings are treated by vacuum heating at 970 ℃, quenching(5 bar nitrogen cooling or oil quenching) and high temperature tempering at 580 ℃. Its mechanical properties and microstructure were examined after heat treatment. The results show that the mechanical properties of KMN steel after gas quenching and high temperature tempering are slightly lower than those of oil quenching and high temperature tempering, and the microstructure is mainly tempered sorbite. KMN steel can obtain similar mechanical properties and microstructure after air quenching or oil quenching and high temperature tempering.