等离子堆敷铜-钢异种金属焊接接头性能及结合机理研究

Study on the Bonding Properties and Mechanism of Copper-steel Dissimilar Metal Joint Deposited by Plasma Arc

利用光学显微镜观察铜-钢异种金属堆敷接头的显微结构及显微组织构成。对异种金属接头进行剪切强度测试,采用扫描电镜对脉冲等离子弧铜-钢异种金属堆敷接头结合机理进行研究。光学微观金相研究表明:铜-钢异种金属堆敷接头界面平整光洁,接头界面清晰可见,无气孔、裂纹等缺陷,实现了无熔深焊接;距堆敷接头界面28μm外的铜侧没有铁的偏析和渗透现象,故不存在堆敷接头的脆化现象。力学性能试验表明,堆敷接头界面剪切强度大于纯铜的剪切强度。扫描电镜测试表明,铁向铜中的扩散较铜向铁中的扩散明显,室温时在堆敷接头界面扩散过渡区内,形成了铜、铁的过饱和α+ε固溶体,从而实现了冶金结合。

The fine texture and microstructure of dissimilar metal joint was observed with microscope and shear strength of the joints was tested. The bonding mechanism was studied by mean of SEM. The optical macroscopic experimental results indicate that the interface of copper-steel joint deposited by plasma arc is smooth and there are not any welding defects such as gas porosity and crack. Therefore,a weld without penetration between dissimilar metal is achieved. The segregation and permeation of iron is not found in the copper adiacent to the joint interface. Hence, the phenomena of embitterment can not occur in the deposited joints that is 28μm away from the joint interface. Mechanical property experiments show that the shearing strength of weld is higher than that of deposited copper. The SEM tests indicate that diffusion from iron to copper is more obvious than that from copper to iron. In the transition region of deposited joint, the oversaturated α＋ε solid solution are formed in room-temperature,which indicates the copper layer and the steel body are well joined metallurgy.