H13钢激光熔覆Co基涂层组织及热疲劳性能

发布时间：2018-03-19 05:08

本文选题：热作模具钢　切入点：激光熔覆　出处：《强激光与粒子束》2017年02期 　论文类型：期刊论文

【摘要】：针对热作模具用H13钢工况下易产生热疲劳失效的问题,采用Nd:YAG激光器在H13钢表面制备Co基合金涂层。利用光学显微镜、扫描电镜、能谱仪和X射线衍射仪,对涂层组织、合金元素分布及物相组成进行检测。利用显微硬度计和热震实验法,测试热疲劳对Co基合金涂层和淬火回火态H13钢硬度影响。结果表明,Co基合金涂层从底部到表层,依次为平面晶、胞状晶、树枝晶和等轴晶。Co基合金涂层物相主要由γ-Co和M_(23)C_6相组成,热疲劳后涂层表面形成M_2O_3和M_3O_4(M=Fe,Co,Cr)氧化物。Co基合金涂层硬度最高可达706HV0.2且呈梯度降低;热循环1000次后,Co基合金涂层表面硬度降低24.4%,H13钢表面硬度降低37.7%,Co基合金涂层硬度下降幅度低于H13钢。热循环1000次后,Co基合金涂层表面未发现明显热裂纹,H13钢表面形成大量网状热裂纹。Co基合金涂层中,Cr元素形成致密Cr_2O_3氧化膜使其热疲劳性能优于H13钢。
[Abstract]:Aiming at the problem of thermal fatigue failure of H13 steel used in hot working die, Co-based alloy coating was prepared on H13 steel surface by Nd:YAG laser. The microstructure of the coating was studied by optical microscope, scanning electron microscope, energy spectrometer and X-ray diffractometer. The effect of thermal fatigue on the hardness of Co-based alloy coating and quenched tempered H13 steel was tested by microhardness tester and thermal shock test. The results showed that the coating of Co-based alloy was from the bottom to the surface. The coating phases of planar crystal, cellular crystal, dendrite and equiaxed crystal. Co-based alloy coating are mainly composed of 纬 -Co and Mash23C6 phases. After thermal fatigue, the surface of the coating is composed of M _ S _ 2O _ 2O _ 3 and M _ 3O _ 4M _ 2O _ 4 / M _ 3O _ 4 / M _ 2O _ 4 / Fe _ (CoCoCr)) oxides. The hardness of Co-based alloy coating is up to 706HV0.2 and decreases in gradient. After 1000 cycles, the hardness of Co-based alloy coating was reduced by 24.4% and 37.7% respectively. The hardness of Co-based alloy coating was lower than that of H13 steel. After 1000 cycles, no obvious hot crack was found on the surface of H13 steel. A large number of mesh-like hot cracks. Co-based alloy coating formed dense Cr_2O_3 oxide film, which resulted in better thermal fatigue performance than H13 steel.
【作者单位】：重庆理工大学材料科学与工程学院;重庆市高校模具技术重点实验室;重庆理工大学工程训练与经管实验中心;
【基金】：重庆市高校模具技术重点实验室开放课题(MT201505)
【分类号】：TG174.4

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