表面纳米化过程中18CrNiMo7-6钢的软化与硬化  

Softening and hardening of 18CrNiMo7-6 steel during surface nanocrystallization treatment

作　　者：朱敏 朱万全 帅林飞 马国强 吴桂林[1] Zhu Min;Zhu Wanquan;Shuai Linfei;Ma Guoqiang;Wu Guilin(College of Materials Science and Engineering,Chongqing University,Chongqing 400045,China)

机构地区：[1]重庆大学材料科学与工程学院,重庆400045

出　　处：《金属热处理》2019年第1期152-156,共5页Heat Treatment of Metals

基　　金：国家重点研发计划专项(2016YFB0700403)

摘　　要：对淬火后低温回火的18CrNiMo7-6钢采用旋转加速喷丸技术进行表面纳米化处理,研究了18CrNiMo7-6钢纳米化过程中的软化和硬化现象。结果表明:经旋转加速喷丸处理后,钢的拉伸性能轻微提升。样品厚度方向上不同深度位置同时出现了硬化与软化现象,其中,心部和最表层硬度都有所增加,而样品次表层硬度却较喷丸前轻微降低,从而使得样品的显微硬度在厚度方向上呈现"W"型分布。在对样品喷丸前后不同深度位置的微观组织表征后发现,材料次表面的软化现象与该位置发生的动态回复有关;而心部和最表层虽然都发生硬化,其强化机制也不尽相同。Rotationally accelerated shot peening( RASP) treatment was applied to a quenched and low-temperature-tempered 18CrNiMo7-6steel for surface nanocrystallization,then softening and hardening of the steel during surface nanocrystallization were studied. The results show that the tensile strength of the samples after RASP is slightly improved. The microhardness test reveals that hardening and softening occur simultaneously at different depths in the cross-section of samples after RASP. Specifically,the superficial and central parts of samples are hardened while the subsurface softened,resulting a "W" shaped distribution of cross-sectional microhardness. Characterization of microstructures at different depths through the thickness direction of samples before and after RASP treatment shows that the softening occurring in the subsurface is attributed to dynamic recovery,while the hardening in the superficial and the central parts is caused by different mechanisms.

关 键 词：旋转加速喷丸 表面纳米化 18CrNiMo7-6钢 显微硬度 强化机制 

分 类 号：TG142.1[一般工业技术—材料科学与工程]