激光辐照区中心温度对高速钢刀具熔覆WC/Co陶瓷层裂纹与组织的影响  

Effect of Laser Irradiation Area Central Temperature on Crack and Microstructure of M2 High-speed Steel Cutter Surface Coating WC/Co by Laser Cladding

作　　者：陈翔 张德强[2] 李金华[2] 孙文强 朴若华 CHEN Xiang;ZHANG De-qiang;LI Jin-hua;SUN Wen-qiang;PU Ruo-hua(Engineering Training Center,Liaoning University of Technology,Jinzhou 121001,China;School of Mechanical Engineering and Automation,Liaoning University of Technology,Jinzhou 121001,China;Training Center,Dalian Economic and Trade School,Dalian 116000,China)

机构地区：[1]辽宁工业大学工程训练中心,辽宁锦州121001 [2]辽宁工业大学机械工程与自动化学院,辽宁锦州121001 [3]大连市经济贸易学校实训中心,辽宁大连116000

出　　处：《表面技术》2021年第4期113-124,共12页Surface Technology

基　　金：辽宁省高等学校产业技术研究院项目(cyyjy2018011)。

摘　　要：目的研究M2高速钢刀具表面激光熔覆WC/Co陶瓷层的辐照区中心温度对熔覆层边界裂纹、组织的影响规律与裂纹产生机理。方法采用IPG光纤激光器在M2高速钢刀具表面制备WC/Co陶瓷熔覆层,对多因素激光工艺参数进行耦合,用刀具基体表面辐照区的中心温度(T)和作用于单位质量粉末的中心温度(η)对熔覆层进行分析。运用显微硬度计、SEM、EDS等手段表征熔覆层的宏观形貌、显微硬度与组织。结果T小于3535 K时,熔覆层通常表现为单边裂纹;T达到4329 K时,熔覆层裂纹长度及宽度成倍增加并沿结合线的方向扩展;T达到5009 K以上时,熔覆层纵向贯穿裂纹数量增加,熔覆层内部开始出现大面积的组织缺陷。η小于19884 K/g时,熔覆层最高硬度数值与其近乎成等比增长趋势,熔覆层主要由WC胞状晶、W2C枝晶为主要强化相的不规则组织构成;η为19884 K/g时,熔覆层最高硬度为1400HV;η达到19884 K/g以上时,熔覆层最高硬度值逐渐下降,熔覆层组织继续长大并开始团聚,逐渐形成以WC为主要强化相的块状组织结构;η超过23614 K/g时,熔覆层左右边界结合区出现比较明显的富WC陶瓷层。结论在辐照区中心温度小于3535 K时,WC/Co陶瓷层内裂纹可以较为稳定地控制在熔覆层边界处。裂纹的源头多在熔覆层与基体结合的左右边界处,随着中心温度升高,裂纹沿熔覆层结合线方向扩展延伸。作用于单位质量粉末的中心温度对陶瓷熔覆层最高显微硬度的影响最为明显。η较低时,激光温度梯度与熔凝速度之比对陶瓷熔覆层的组织形态和硬度影响更大;η较高时,冷却速度对陶瓷熔覆层的组织形态和硬度影响更大。陶瓷熔覆层边界裂纹的产生和扩展与熔覆层和基材的物性参数差异、温度梯度变化、基材翘曲变形、陶瓷相分布情况有关。The effect and the mechanism of the central temperature of the surface irradiated area by laser on boundary crack and microstructure of WC/Co ceramic cladding layer on the surface of M2 high-speed steel cutter are studied.The ceramic cladding layer are fabricated on the surface of M2 high-speed steel cutter by IPG fiber laser system,the multi-factor laser process parameters are coupled,the cladding layer are analyzed by the central temperature of the irradiated area on the cutter substrate surface(T)and central temperature of unit mass powder(η),and the macroscopic morphology,microhardness and microstructure of the cladding layer are characterized by microhardness meter and SEM,EDS.When the T is less than 3535 K,the cladding layer usually exhibits unilateral crack;when the T reaches 4329K,the crack length and width of the cladding layer increase exponentially and expand along the bonding line.When the T reaches more than 5009 K,the number of longitudinal penetration cracks in the cladding layer increases,and large area tissue defects begin to appear inside the cladding layer.When theηis 19884 K/g,the maximum microhardness of the cladding layer is 1400HV;when theηis less than 19884 K/g,the maximum microhardness of cladding layer and the central temperature of unit mass powder were almost equal growth trend to each other,and the microstructure of the cladding layer is mainly irregular WC cellular crystal and W2C dendrite as the main strengthening phase.When theηreaches more than 19884 K/g,the maximum microhardness value of the cladding layer decreases gradually,and the tissue in the cladding layer continues to grow and begin to agglomerate,and gradually forms a massive structure with WC as the main strengthening phase.When theηexceeds 23614 K/g,the WC rich ceramic layer appeared in the left and right boundary bound region of the cladding layer.When the central temperature of the irradiated area is less than 3535 K,the cracks in the WC/Co ceramic layer can be controlled stably at the boundary of the cladding la

关 键 词：激光熔覆 中心温度 边界裂纹 WC/Co陶瓷熔覆层 显微组织 高速钢刀具 

分 类 号：TH142.2[一般工业技术—材料科学与工程] TG174.4[机械工程—机械制造及自动化]