摘要
针对H13钢离子渗氮精密热锻模具出现早期疲劳裂纹或龟裂问题,开展温度520℃、气压250 Pa、不同氮氢比条件下的离子渗氮试验,以考察渗氮气氛中氮氢比对渗层组织及耐磨性能的影响规律。利用X射线衍射仪、共聚焦显微镜、扫描电镜、显微硬度计和摩擦磨损试验机分析不同氮氢比渗氮后渗层的相结构、显微组织、显微硬度及耐磨性能。结果表明:渗氮时间3 h、氮氢比为1∶3、1∶4、1∶5时,渗层物相主要由ε-Fe_(2-3)N、γ′-Fe_(4)N、α_(N)-Fe(N)相组成,氮氢比为1∶8时渗层物相主要为γ′和αN相;渗层深度及硬度随渗氮气氛中氮浓度降低而减小,氮氢比为1∶8时,延长渗氮时间可增加渗层厚度,在60μm渗层深度内硬度可达800~900 HV_(0.1)。氮氢比为1∶3、1∶4的渗层的磨损机理以疲劳磨损为主;氮氢比为1∶5、1∶8的渗层的磨损机理以磨粒磨损为主。采用氮氢比为1∶8对H13钢进行离子渗氮,渗层中无化合物层和脉状组织,渗层可获得适中的硬度和较佳的韧性,具有较好的耐磨性能。
Aiming at the problem of early fatigue cracks in plasma nitrided H13 steel precision hot forging dies,plasma nitriding process tests were conducted under a nitriding temperature of 520℃,a pressure of 250 Pa and different nitrogen to hydrogen ratio conditions to reveal the effect of nitrogen hydrogen ratio in a nitriding atmosphere on the microstructure and wear properties of coating.The phase structures,micro-structure,microhardness and wear properties of the nitrided coatings with different nitrogen hydrogen ratios were examined and analyzed using X-ray diffraction(XRD),confocal microscopy,scanning electron microscopy(SEM),microhardness tester and a friction and wear test ma-chine.Results showed that the nitrided coatings with N∶H=1∶3,1∶4 and 1∶5 after 3 h mainly consisted ofε-Fe_(2-3)N,γ′-Fe_(4)N andα_(N)-Fe(N)phases,respectively,while nitrided coatings with N∶H=1∶8 mainly consisted ofγ′and α_(N).The depth and hardness of the nitri-ded layers decreased with the reduction of N concentration in the nitriding atmosphere.The depth of the nitrided layer with N∶H=1∶8 in-creased with nitriding time,and the hardness reached 800~900 HV_(0.1)at a depth of 60μm.The wear mechanisms were mainly fatigue wear for the nitrided coatings with N∶H=1∶3,1∶4,and abrasive wear for the coatings with N∶H=1∶5,1∶8.When ion nitriding H13 steel with a nitrogen to hydrogen ratio of 1∶8 was carried out,there was no compound layer or vein like structure in the nitriding layer,and the nitriding layer could obtain moderate hardness and better toughness,with good wear resistance.
作者
高玉新
王均波
程虎
GAO Yuxin;WANG Junbo;CHENG hu(College of Mechanical and Electrical Engineering,Rizhao Polytechnic,Rizhao 276826,China;Zhejiang Provincial Key Laboratory for Cutting Tools,Taizhou 318000,China)
出处
《材料保护》
CAS
CSCD
2024年第8期192-197,共6页
Materials Protection
基金
日照职业技术学院校企研究课题(2022H16)
台州市科技计划项目(2002gy10)。
关键词
H13钢
离子渗氮
氮氢比
微观组织
耐磨性能
H13 steel
plasma nitriding
ratio of nitrogen to hydrogen
microstructure
wear resistance
作者简介
通信作者:高玉新(1974-),副教授,博士,研究领域:模具表面再制造工程,电话:15163308930,E-mail:yxin_gao@163.com。
