摘要
三明治复合钎料是实现硬质合金与钢可靠钎焊连接的重要技术,复合层间及其与基体间的界面层组织形态对力学性能有着重要影响.系统分析了不同钎焊温度、时间条件下梯度三明治复合钎料钎缝组织演变规律,分析了影响力学性能的关键因素.试验结果表明,梯度三明治复合钎料与钢和硬质合金基体界面形成分为4个阶段:界面组织形成、长大、溶合、重排.梯度钎料中间CuMn2层随着保温时间的延长,由初始连续状逐渐变为孤立的小岛,周围被低Mn铜固溶体包围;继续延长保温时间,CuMn2层消失,整个钎缝由铜固溶体、银固溶体和银铜共晶组成.钎缝抗剪强度在780℃、保温2.5 min时达到最高285 MPa,Co,Ni元素此时发生长程扩散,聚集在中间层CuMn2附近,提高了CuMn2中间层强韧性,在断口韧窝的根部分布着Co基颗粒强化相;进一步延长保温时间,Co,Ni等钎缝强韧化元素开始分散,钎缝组织粗化,强度降低.
Sandwich composite filler metal is an important technical means to realize reliable brazing connection between cemented carbide and steel.The microstructure of the composite layer and the interface layer between the composite layer and the matrix has an important influence on the mechanical properties.The microstructure evolution of brazing joint of gradient sandwich composite filler metal under different brazing temperature and time conditions was systematically studied,and the key factors affecting the mechanical properties were analyzed.The research results showed that the interfacial formation of gradient sandwich filler metal with steel and carbide matrix could be divided into four stages:interfacial structure formation,growth,fusion and rearrangement.The CuMn2 layer in the middle of the gradient filler metal gradually changed from the initial continuous shape to an isolated island surrounded by low Mn copper solid solution with the extension of holding time.As the holding time continued,CuMn2 layer disappeared and the whole brazing joint was composed of copper solid solution,silver solid solution and silver copper eutectic.The shear strength of the brazing joint reached the highest 285 MPa when the temperature was kept at 780℃ for 2.5 min.At this time,the Co and Ni elements had long range diffusion and accumulated near the CuMn2 interlayer,which improved the strength and toughness of the CuMn2 interlayer.The Co-based particle strengthening phase was distributed in the root of the fracture dimple.Further extension of holding time,Co,Ni and other brazing elements began to disperse,the brazing structure coarsened,the strength decreased.
作者
张冠星
钟素娟
沈元勋
董宏伟
薛行雁
ZHANG Guanxing;ZHONG Sujuan;SHEN Yuanxun;DONG Hongwei;XUE Hangyan(State Key Laboratory of Advanced Brazing Filler Metals&Technology,Zhengzhou Research Institute of Mechanical Engineering Co.,Ltd,Zhengzhou,450001,China)
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2023年第9期37-43,I0005,共8页
Transactions of The China Welding Institution
基金
国家自然基金资助项目(U1904197)。
关键词
梯度三明治钎料
界面扩散
抗剪强度
gradient sandwich filler metal
interfacial diffusion
shear strength
