Study on Liquid Phase Diffusion Welding of Nickel Base Superalloy Used Ni-B System Alloyed Layer Formed on Bonding Surface with Sputtering.

Abstract

Liquid phase diffusion welding of Ni-base superalloy (IN738LC) was studied. In this study, the surface of IN738LC was cleaned by Ar ion bombardment and an alloyed layer (Ni-B alloy, Ni-Cr-Si-B alloy) was deposited on the bonding surface by sputtering.In this report, the effect of Ar ion bombardment on melting temperature of alloyed layer formed on base metal, penetration of alloyed layer into base metal and weldability, and the effect of composition of alloyed layer on melting temperature of alloyed layer, penetration of alloyed layer into base metal and weldability were investigated.The main results indicated that : (1) The penetration was increased by cleaning with Ar ion bombardment.(2) Penetration of Ni-Cr-Si-B alloyed layer was larger than penetration of Ni-B alloyed layer and melting temperature range of Ni-Cr-Si-B alloyed layer was larger than melting temperature range of Ni-B alloyed layer.(3) Pressure of welding used Ni-Cr-Si-B alloyed layer was lower than pressure of welding used Ni-B alloyed layer. (4) Weldability with cleaning was better than weldability without cleaning (5) Tensile strength of welded joint was the same as tensile strength of base metal, but elongation and reduction of area were lower than elongation and reduction of area of base metal. But mechanical property was improved by diffusion heat treatment.