冷处理对42CrMoA钢表面QPQ处理层的影响  

Effect of cryogenic treatment on QPQ layer on 42CrMoA steel surface

作　　者：郑晓辉[1] 何东昱 刘晓亭[1] 杜军[1] 谭俊[1] 

机构地区：[1]装甲兵工程学院再制造技术国家重点实验室,北京100072

出　　处：《金属热处理》2017年第8期152-157,共6页Heat Treatment of Metals

摘　　要：研究了-60℃冷处理对42Cr Mo A钢表面盐浴渗氮与氧化复合(QPQ)处理层的影响。采用扫描电镜观察截面形貌,用纳米压入法测定了沿深度方向的硬度变化,用划痕法测定了涂层/基体的结合强度,用X射线衍射(XRD)测定涂层物相变化情况。结果发现:QPQ处理后42Cr Mo A钢表面生成疏松层、渗氮层和扩散区,疏松层由氧化层(~10μm)和氧-氮共混区(~5μm)组成。渗氮层(10~15μm)硬度>800 HV0.05,扩散区(0.3~0.4 mm)硬度从约500 HV0.05梯度降低到基体硬度(约325 HV0.05)。QPQ处理在42Cr Mo A钢表面生成的渗氮层与扩散区结合较好,结合强度(划痕法)约25 N。-60℃冷处理未对QPQ处理层的硬度以及渗氮层/扩散区的结合强度产生显著影响。但冷处理显著弱化疏松层与渗氮层的结合,导致疏松层在较大范围剥离。Effect of-60 ℃ cryogenic treatment on QPQ layer of 42 CrMoA steel surface was studied. The scanning electronic microscopy,X-ray diffraction,nano-indentation and scratch test were employed to evaluate the morphology,microstructure and mechanical properties of the QPQ layer,respectively. It is found that the QPQ treated layer on 42 CrMoA steel surface consists of loose layer,nitride layer and diffusion zone; The loose layer is composed of oxide layer（ 〈10 μm） and oxide-nitride blended zone（〈 5 μm）; The hardness of nitrided layer（ 10-15 μm） is above 800 HV0. 05 and the hardness in diffusion zone（ 0. 3-0. 4 mm） reduces gradually from 500 HV0. 05 to325 HV0. 05（ substrate hardness）; The bonding strength between nitrided layer and diffusion zone is about 25 N. It is concluded that the cryogenic treatment at-60 ℃ does not considerably affect the hardness and bonding strength of nitrided and diffusion layers,but weakens the bonding between loose layer and nitrided layer which brings a large scale peeling off in the loose layer.

关 键 词：冷处理 QPQ处理 硬度 结合强度 渗氮层 

分 类 号：TG162.7[金属学及工艺—热处理]