钛合金管件与不锈钢内衬管真空扩散焊工艺研究

Research on Vacuum Diffusion Welding Process of Titanium Alloy Pipe and Stainless Steel Lined Pipe

采用真空扩散焊工艺实现了TC4钛合金管件与15-5PH不锈钢内衬管的连接,研究了焊接温度、保温时间、中间层等对焊接界面结构、界面扩散及焊合率的影响规律。结果表明,在焊接温度为900℃,保温时间为4 h,Ni中间层厚20~30μm的条件下,可实现TC4管件与15-5PH内衬管的有效连接,焊合率最高。焊接接头界面产物组成,从钛合金侧到不锈钢侧依次为:TC4-(α+β)—NiTi_(2)—Ni_(x)Ti_(y)P_(z)—Ni_(3)Ti—FeNi_(3)—γ-(15-5PH)。焊接温度和中间层是影响连接质量最主要的因素,采用低于880℃的焊接温度或不采用中间层时,无法实现TC4管件与15-5PH内衬管的可靠扩散连接。保温时间为4 h时,焊接温度从890℃升高到910℃,焊合率和扩散层厚度先升高后略降低。焊接温度为900℃时,保温时间从2 h延长到4 h,焊合率和扩散层厚度均升高。

The vacuum diffusion welding process was used to realize the connection of TC4 titanium alloy pipe and 15-5PH stainless steel lined pipe.The influence of welding temperature,holding time and intermediate layer on the welding interface structure,interface diffusion behavior and welding rate was studied.The results show that when the welding temperature is 900℃,the holding time is 4h,and the Ni intermediate layer is 20-30μm,the welding between TC4 titanium alloy pipe and 15-5PH stainless steel lined pipe can be achieved,and the welding rate is the maximum.The interface product composition of the welded joint is TC4-(α+β)—NiTi_(2)—Ni_(x)Ti_(y)P_(z)—Ni_(3)Ti—FeNi_(3)—γ-(15-5PH) from the titanium alloy to the stainless steel.The welding temperature and the intermediate layer are the most important factors affecting the diffusion connection.If the temperature is lower than 880℃or the intermediate layer is not used,reliable connection cannot be achieved.When the holding time is 4 h,with the welding temperature increasing from 890℃ to 910℃,the welding rate and the diffusion layer thickness increase first and then decrease slightly.When the welding temperature is 900℃,with the holding time increasing from 2 h to 4 h,the welding rate and the diffusion layer thickness increase.