摘要
利用宽束激光在Q550钢表面制备Ni60/WC复合熔覆层,分析熔覆层显微组织、元素分布和物相组成,通过剪切试验定量表征熔覆层/基体界面结合强度,并对断口形貌进行分析阐述界面断裂机制.结果表明,熔覆层中WC颗粒部分溶解,形成了具有复杂结构的析出相,内核为M_(23)C_6碳化物(M代表Cr,W,Fe),外部为M_(23)C_6复合碳化物和γ-Ni共晶.平面晶和树枝晶在界面上生长,形成牢固冶金结合.激光功率大于2.8 kW时,熔覆层抗剪强度达到279.8 MPa以上,超过母材的75%.断口分析表明,熔覆层界面具有脆性-韧性混合断裂特征,低功率下WC颗粒在界面上沉积,削弱了界面结合强度.
Ni60/WC based composite coatings were prepared on surface of Q550 steel by using wide-band laser cladding technology.Microstructure characteristics,elemental distribution and phase constitution of composite coatings were analyzed.Shear strength tests were carried out for quantitative measurement of bonding force at coating/substrate interface,and fracture surface morphologies were investigated to analyze the failure mechanism of interfaces.Results indicated the WC particles were partially dissolved in composite coating and precipitates with complicated structure were in-situ formed.The cored-eutectic structure consistsof hard M_(23)C_6(M represents for Cr,Fe and W) carbides inside and is surround by eutectic of M_(23)C_6 and γ-Ni matrix.The formation of planar growth and dendrites facilitated a dense metallurgical bonding on the interface.As the laser power being increased to 2.8 kW,the shear strength of composite coating is 279.8 MPa,which is 75% of that of base metal.Fracture surface analysis indicated the fracture mechanism of coating interface is a mixture of brittle fracture and ductile fracture.The bonding force of coatings made by lower power is decreased due to the WC particles get accumulated at the interface.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2016年第12期49-52,共4页
Transactions of The China Welding Institution
基金
国家自然科学基金资助项目(51575316)
关键词
宽束激光熔覆
显微组织
抗剪强度
断口形貌
wide-band laser cladding
microstructure
shear strength
fracture surface
