摘要
目的提高P20模具钢的表面硬度和耐磨性能。方法采用激光熔凝技术对P20模具钢表面进行强化处理。通过硬度梯度检测和摩擦磨损测试,分别评价熔凝层的硬度分布特征和耐磨性能,并通过光学显微镜和扫描电子显微镜对熔凝层及磨痕形貌进行分析。结果使用激光输出功率为500W、光斑直径为2.5mm、聚焦透镜距离为40 mm、扫描速度为6 mm/s、搭接率为45%、氮气保护的激光熔凝工艺所得熔凝层的组织细小,无脱碳、畸变、裂纹等缺陷,熔凝处理质量高。熔凝过程中单道激光熔凝层呈半椭圆形分布,最大深度为610~620μm。熔凝处理后表面硬度提升显著,熔凝层的硬度分布与熔凝层的区域位置有关,具有较高硬度且硬度保持基本稳定的熔凝层深度约为400μm;单道激光熔凝层最高硬度可达460~480HV,重叠影响区即双熔凝区的最高硬度在540~560HV之间,即熔凝层硬度普遍较基体硬度提高了60%以上。此外,P20模具钢经过激光熔凝处理后耐磨性能提升明显,其平均摩擦因数约为0.85,熔凝处理的磨损失重较未处理的试样减少了约61%,其磨损机制主要表现为磨粒磨损和少量的黏着磨损或剥落脱离。结论激光熔凝处理能够显著提高P20模具钢的表面硬度和耐磨性能,试验采用的激光熔凝工艺可在P20钢表面获得硬度较高且稳定可靠的熔凝层深度在400μm左右,能将P20模具钢的表面硬度及耐磨性提高60%以上。
The work aims to improve the surface hardness and wear resistance of P20 die steel.The surface of P20 die steel was strengthened by laser surface melting technology.The hardness distribution characteristics and wear resistance of the laser surface melted layer were evaluated by the hardness gradient test and friction and wear test.In addition,the morphology of the laser surface melted layer and wear marks were analyzed by optical microscope and scanning electron microscope.With the laser output power of 500 W,the spot diameter of 2.5 mm,the focusing lens distance of 40 mm,the scanning speed of 6 mm/s and the lap rate of 45%,the microstructure of the laser surface melted layer obtained by nitrogen protection laser surface melting process was fine,without decarbonization,distortion,crack and other defects,and the laser surface melted treatment quality was high.According to the microstructure and hardness distribution characteristics of the melted layer,from the surface layer to the matrix,the laser surface melted layer could be divided into laser melted zone,heat affected zone,overlapping affected zone and non-affected zone which was named the matrix zone.In the process of laser surface melting,the single-channel laser surface melted layer presented a semi-elliptical distribution,and the maximum depth was about 610-620μm.After laser surface melting treatment,the surface hardness increased significantly.The hardness distribution of the laser surface melted layer was related to the location of the layer.The depth of the laser surface melted layer with high hardness and stable hardness was about 400μm.Beyond this depth,the hardness of the melted layer tended to decrease.The maximum hardness of the single laser surface melted layer could reach 460-480HV,and the maximum hardness of the overlapping affected zone,namely the double melting zone,was between 540-560HV,namely that the hardness of laser surface melted layer was generally more than 60%higher than that of matrix.The hardness of the double melted zone was about
作者
李勇
缪星旭
张成佳
姜鹤明
王坤
王小瑾
LI Yong;MIAO Xingxu;ZHANG Chengjia;JIANG Heming;WANG Kun;WANG Xiaojin(National Collaborative Innovation Center of Laser Manufacturing and Materials Technology,Zhejiang Industry&Trade Vocational College,Zhejiang Wenzhou 325026,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2024年第9期209-215,共7页
Surface Technology
基金
温州市重大科技创新攻关项目(ZG2020035)。
关键词
P20模具钢
激光熔凝
熔凝层
显微硬度
金相组织
摩擦磨损
P20 die steel
laser surface melting
melted layer
microhardness
microstructure
friction and wear
