摘要
采用力学性能测试、SEM、TEM、XRD等试验方法研究了回火温度和时间对二次硬化型超高强度钢Aer Met340的力学性能及微观组织的影响。结果表明,Aer Met340钢的回火曲线呈现明显的二次硬化现象,获得最佳综合性能的回火工艺为482℃×5 h空冷;抗拉强度、规定塑性延伸强度峰值分别为2460 MPa、2061 MPa,对应的回火温度分别为450、468℃;在低温回火时,Aer Met340钢主要由回火马氏体和ε-碳化物组成,高于468℃回火时,基体中弥散分布着细小针状M2C碳化物,这是该钢获得高强韧性的主要原因之一;随着回火温度的上升,合金碳化物M2C的主要合金成分Fe、Cr、Mo含量明显升高,使得M2C的晶格常数发生变化,并逐渐脱离了与基体的共格关系。
The effects of tempering temperature and time on the mechanical properties and microstructure of a secondary hardening ultra-high strength steel AerMet340 were investigated by means of mechanical test, SEM, TEM and XRD respectively. The results show that the tempering curve of AerMet340 steel presents secondary hardening phenomenon obviously, and the tempering process to obtain the best properties is tempered at 482 ℃ for 5 h and then air cooled. The peak values of tensile strength and yield strength are 2460 MPa and 2061 MPa, corresponding to the peak temperature respectively of 450 ℃ and 468 ℃. When tempered at lower temperatures, AerMet340 steel is mainly composed of tempered martensite and e-carbides. When tempered above 468 ℃, the wee acicular ME C carbides precipitate with distributing of dispersion in matrix, which is one of the main reasons for the high strength of the steel. Moreover, with tempering temperature rising, the contents of Fe, Cr and Mo, as the main components of MEC carbides, increase significantly, which makes the lattice constant of ME C change and the precipitates are divorced from a coherent relationship with the matrix gradually.
出处
《金属热处理》
CAS
CSCD
北大核心
2015年第8期101-105,共5页
Heat Treatment of Metals
