过渡液相扩散焊连接工艺参数对DD407母材液化的影响

为了将瞬间液相扩散焊的液相形成过程与固相扩散焊复合,充分利用TLP及固相扩散焊的优点,需要研究接头界面处母材液化规律。选用DD407镍基单晶高温合金作为试验材料,中间层合金采用含B为3.5%的BNi9进行TLP连接,观察母材液化宽度和接头宽度在不同工艺参数下的变化。通过分析得到:母材液化区宽度随着加热温度升高及保温时间增长而增加,在焊接温度为1100℃,保温时间为5min,中间层厚度为150μm的情况下,母材液化的宽度达到65.8μm;中间层厚度对母材液化的影响程度相对较大,主要降熔元素B的总量增加;TLP连接过程中,母材液化的过程为降熔元素B不断向母材中扩散,导致母材液化宽度增加,但随着扩散的进行,B元素的含量逐渐降低引起等温凝固,从而在一定程度上影响了表面清理的效果。

Effect of TLP Process Parameters on Liquefaction of DD407 Base Metal

In order to make full use of the advantages of TLP and solid state diffusion welding for combination of these two processes,it was necessary to study the liquefaction law of base metal at the joint interface.DD407 nickelbased single crystal superalloy was joined by intermediate layer alloy of BNi9 with 3.5%B.The variations of width of joint and liquefied base metal as process parameters were investigated.Results were as follow:With the increase of welding temperature and the holding time,the width of the liquefaction zone increased.When welding with interlayer in thickness of 150μm at temperature of 1100℃and holding time of 5 min,the width of liquefied base metal reached 65.8μm.The effect of the thickness of interlayer on the liquefaction of the base metal was relatively higher due to the increase of B contents.The liquefying procedure of base metal was summarized as follow:interacted region of base metal were liquefied by diffusion of melting point depressing element of B,which resulted in the increase of the liquefied area width.But the content decrease of B element in the interlayer gave rise of isothermal solidification,which ceased the further liquefaction,thus the action of surface cleaning was affected in some content.