摘要
为优化渗氮工艺,提高渗氮层的厚度与硬度,提出用超声波冷锻技术(Ultrasonic cold forging technology,UCFT)对Cr12MoV模具钢进行表面纳米化预处理,并在450℃和520℃两个温度条件下离子渗氮。采用扫描电镜、金相显微镜、白光形貌仪、X射线衍射仪和维氏显微硬度计对样品的微观组织结构和性能进行表征。结果表明:UCFT是一种能与离子渗氮有效复合的预处理工艺,经UCFT表面纳米化预处理后,Cr12MoV模具钢表面形成表面硬度约520 HV,厚度为350μm的塑性变形影响层;经UCFT表面纳米化预处理后和离子渗氮复合处理后,渗氮层厚度与硬度与原始样品直接渗氮相比有显著提高;UCFT预处理后在520℃离子渗氮4 h,材料表面硬度可高达1350 HV,复合改性层厚度也可增至约400μm。
To enhance the thickness and hardness of nitrided layer,ultrasonic cold forging technology（UCFT） was introduced as a pre-treatment.To optimize plasma nitriding process,both original samples and samples pretreated by UCFT were nitrided in nitrogen plasma at the temperature of 450 ℃ and 520 ℃.The hardness,microstructure,morphology and composition of the nitrided samples surface were investigated by micro-hardness tester,optical microscope（OM）,scanning electron microscope（SEM）,3D profilo-meter and X-ray diffraction（XRD）.The results show that UCFT can be introduced as a befitting pre-treatment means of plasma nitriding to Cr12MoV die steel,and an effective layer caused by severe plastic deformation with a surface hardness of 520 HV as well as a depth of about 350 μm was formed.Comparing with the nitrided original samples,a thicker and harder nitrided layer was formed on the surface of Cr12MoV die steel after the surface combined modification.The surface hardness of the samples nitrided at 520 ℃ for 4 h after UCFT pre-treatment reachesd to 1350 HV,meanwhile,its thickness was about 400 μm.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2013年第7期129-135,共7页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金项目(51275494)
中央高校基本业务费项目(2012ZY51)
科技部国际合作重点项目(2010DFR50070)
清华大学摩擦学国家重点实验室开放基金项目(SKLTKF11B04)
