摘要
本文选用25合金钢作为新一代低温阀门钢的实验材料。研究分析深冷处理时间和次数对25合金钢组织和性能影响规律。研究结果表明淬火后组织为细小的板条马氏体,深冷处理后组织为残余奥氏体和片状马氏体,并随着深冷次数和时间的延长,细小弥散的碳化物析出分布在晶界,同时残余奥氏体转变为细小的回火马氏体组织。深冷处理对材料力学性能有明显的影响,硬度和强度随着深冷处理时间和次数增加逐渐增大,但应变却逐渐降低。自然时效72 h后立即二次深冷处理120 min,材料获得最优的力学性能,硬度为52. 6 HRC,屈服强度为1345 MPa,抗拉强度为1390 MPa。深冷处理后材料的线膨胀系数减小,由淬火态的14. 45×10^(-6)/℃减小到12. 26×10^(-6)/℃,而且在低温下表现为比较稳定,达到低温阀门钢的低温服役条件。
In this paper, 25 alloy steel was selected as the experimental material for the new generation of cryogenic valve steel. The effect of time and frequency of deep cryogenic treatment on the microstructure and performance of 25 alloy steel was studied and analyzed. Experimental results show that the microstrue- ture is tiny lath martensite after quenching, and lamellar martensite and retained austenite are obtained af- ter cryogenic treatment. The small dispersion carbides are precipitated and distributed in grain boundary with increasing the time and frequency of deep cryogenic treatment, and the residual austenite transformes into tiny tempered martensite. The cryogenic treatment have obvious effects on mechanical properties, hardness and strength of the material increase gradually with increasing the time and frequency of deep cry- ogenic treatment, but the strain decreases gradually. The material obtaines the optimal mechanical property after the natural aging for 72 h and the secondary deep cooling treatment for 120 min immediately, the hardness is 52.6 HRC, yield strength is 1345 MPa and tensile strength is 1390 MPa. The linear expansion coefficient of material decreases from 14.45 × 10^-6/℃ as quenching state reduced to 12.26 × 10^-6/℃ af- ter cryogenic treatment, and it is relatively stable at the low temperature and reaches the low temperature service conditions of cryogenic valve steel.
作者
刘骁
赵春芳
叶翔
LIU Xiao;ZHAO Chun-fang;YE Xiang(Lishui Vocational ＆ Technical College,Lishui Zhejiang 323000,China)
出处
《热处理技术与装备》
2018年第5期8-14,共7页
Heat Treatment Technology and Equipment
基金
浙江省丽水科技攻关项目(2012ZC010)
关键词
25合金钢
深冷处理
组织
性能
25 alloy steel
deep cryogenic treatment
microstructure
properties
