钛合金与不锈钢超塑性扩散连接工艺及机理研究

Techniques and Mechanism of Superplastic Diffusion Bonding between Titanium Alloy and Stainless Steel

摘要:

基于微细晶超塑性扩散连接方法，对TC4钛合金与1Cr18Ni9Ti不锈钢成功实现了直接扩散连接，系统分析了接头性能、界面微观结构及超塑性扩散连接机理。结果发现：TC4钛合金与1Cr18Ni9Ti奥氏体不锈钢直接超塑性扩散连接时，较佳连接工艺规范为：温度T=760~820 ℃，压力p=6~9 MPa，时间t=20~40 min；接头剪切强度τ＝125.3~148.7 MPa。与一般直接扩散连接相比，连接温度降低了约100 ℃，接头的剪切强度提高了1倍以上，且连接试样无明显变形。细化热处理TC4钛合金与1Cr18Ni9Ti不锈钢超塑性扩散连接时，其接头的形成过程大致可分为3个阶段：形成紧密接触阶段、接触表面激活阶段及靠近活化中心的界面冶金结合区形成阶段。

Abstract:

Direct diffusion bonding between TC4 titanium alloy and 1Cr18Ni9Ti stainless steel were implemented based on the superplastic diffusion bonding (SDB) method. The joint properties, interface microstructures and the mechanism of superplastic diffusion bonding were analyzed. The results show that for direct superplastic diffusion bonding of TC4 alloy to 1Cr18Ni9Ti stainless steel, the shear strength of TC4/1Cr18Ni9Ti joints is 125.3-148.7 MPa under optimal diffusion bonding conditions including the temperature of 760-820 oC, the bonding pressure of 6-9 MPa and the bonding time of 20-40 min. Compared with the conventional diffusion bonding, the bonding temperature can be reduced by about 100 oC while the shear strength of joints is increased by more than one time. And the bonding specimens have no distinct distortion. In the ultrafine superplastic diffusion bonding of TC4 alloy and 1Cr18Ni9Ti stainless steel, the formation process of the bonded joint can be divided into three stages: close contact forming, activation of contact surface and formation of interfacial metallurgy bonded zone nearby the activation center.