提高钎缝耐热性的新途径

高温合金构件真空钎焊通常采用Ni-Cr-Si-B系钎料 ,在钎缝中会形成连续分布的共晶组织 ,使钎缝重熔温度降低 ,耐热性变差 .为解决这一难题 ,研究了一种粉末冶金 -钎焊工艺 ,结果表明 :该工艺可以消除钎缝中低熔点共晶组织 ,并能实现钎缝固溶强化和第二相强化 ,从而提高了钎缝的耐热性 .用K40 3和GH40 3 7合金钎焊接头持久性能分别达到母材的 75 %和 95 %的水平 ,该工艺已用于涡轮导向叶片的修补 .

A new method to improve the heat resistance of the brazing seam

Ni-Cr-Si-B alloys were often used as filler metal for brazing superalloy components. However, continuous eutectics would form in the brazing seam, which would decrease its remelting temperature and heat resistance .To solve the problem, we used powder metallurgy brazing technology. Results showed that when using this new method, the low melting point eutectics disappeared, and the brazing seam were solution strengthened and second phase strengthened at the same time, which would act together to improve the heat resistance of the brazing seam. For instance, the stress rupture life of the brazing joint for K403 and GH4037 alloy could reach 75% and 95% of that of the base metal respectively. This new method had been used in repairing the turbine blades successfully.