超高强钢直接淬火后回火组织与力学性能的研究

Study on Microstructure and Mechanical Properties of Ultra-high Strength Steel after Direct Quenching and Tempering

对试验钢进行了两阶段控轧后直接淬火到室温,研究了250~600℃不同回火温度对组织和性能的影响。结果表明:在低于350℃回火时,试验钢的组织为细小的板条马氏体,碳化物的尺寸细小,且具有良好的强韧性;350℃回火的综合力学性能最好,抗拉强度为1630 MPa,屈服强度为1395 MPa,-20℃冲击吸收功为22 J;高于350℃回火,马氏体板条宽度明显增加,碳化物长大粗化,强度下降;450℃回火,出现粗大的碳化物导致回火脆性,韧性最差。

The test steel was directly quenched to room temperature after two stages of controlled rolling. The effects of different tempering temperatures （250-600 ℃） on microstructure and mechanical properties were investigated. The results show that when the tempering temperature is below 350℃, the microstructure of the test steel is fine lath martensite, the size of the carbide is small and the steel has good strength and toughness; when tempering temperature is 350 ℃, the comprehensive mechanical properties are the best, the tensile strength is 1630 MPa, the yield strength is 1395 MPa, and the impact absorption work at-20℃ is 22 J; when tempering temperature is above 350 ℃, the lath width of martensite increases obviously, the coarsening of carbides increases and the strength decreases; when tempering temperature is 450 ℃, the appearance of coarse carbides leads to temper embrittlement, and toughness is the worst.