摘要
对38CrMoAl钢表面进行离子渗氮与激光淬火复合处理。结果发现复合改性层的平均硬度为750 HV,相比于单一激光淬火层的硬度提高~200 HV,较高的硬度源于激光淬火过程中发生马氏体相变与N的固溶强化作用;复合改性层厚度为856μm,相比于渗氮层提高了195%,相比于激光淬火层提高了94%。复合工艺深层硬化机制为渗氮过程引入的N元素显著降低了合金钢表面奥氏体转变温度,在相同激光工艺下表面发生奥氏体转变的深度增加,因此能够发生马氏体相变强化的深度增加。此外,次表层的硬度与残余应力是抑制疲劳裂纹萌生的关键。复合工艺改性层100μm处的硬度与残余压应力分别为823 HV和520.57 MPa,相比于渗氮试样硬度提高了~200 HV,残余压应力提高了124.31%。根据本文中对疲劳性能的数学分析可以预测,复合改性层的疲劳强度相比于渗氮试样可提高一倍。
The 38CrMoAl steel was processed by duplex treatments of plasma nitriding and laser quench-ing.The results show that the average microhardness for duplex treated layer is 750 HV,which is about 200 HV higher compared with the single laser quenched layer.The superior microhardness is resulted from the martensitic transition as well as the solid solution of nitrogen.The depth of layer for the duplex treated layer is 856μm,which is increased about 195%and 94%in comparison with the nitrided layer and laser quenched layer,respectively.The mechanism of high-depth hardening of duplex treatment lies in the fact of the decrease of austenite transition temperature caused by the introduction of nitrogen.Under the same parameters of laser quenching,the depth of austenitic transition can increase,which means the region of martensitic transition is larger than the counterpart of laser quenched.Additionally,the fatigue crack always initiate beneath the surface,which largely depends on the residual stress and microhardness.The mi-crohardness of 100μm depth is 823 HV,which increases 200 HV than the nitrided layer.The residual compressive stress of 520.57 MPa for the duplex treated layer is 124.31%higher than the nitrided layer.According to the mathematical analysis in this paper,the fatigue strength for the duplex treated layer is twice times higher in comparison with the nitride layer.
作者
梁嘉文
王祎雪
闫牧夫
王禹淞
涂志豪
田野
张媛
王天成
LIANG Jia-wen;WANG Yi-xue;YAN Mu-fu;WANG Yu-song;TU Zhi-hao;TIAN Ye;ZHANG Yuan;WANG Tian-cheng(School of Materials Engineering,Shanghai University of Engineering Science,Shanghai 201620;National Key Laboratory for Precision Hot Processing of Metals,School of Materials Science and Engineering,Harbin Institute of Technology,Harbin Heilongjiang 150001,China)
出处
《热处理技术与装备》
2020年第5期1-7,共7页
Heat Treatment Technology and Equipment
基金
上海工程技术大学大学生创新实验项目(cx1905004)。
