Practicability of Liquid Phase Diffusion Welding by use of Amorphous Interlayers

1985 Fiscal Year Final Research Report Summary

• Project/Area Number: 59850121
• Research Category: Grant-in-Aid for Developmental Scientific Research
• Allocation Type: Single-year Grants
• Research Field: 溶接工学
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: ONZAWA Tadao 東京工業大学, 工, 助教授 (10016438)
• Project Period (FY): 1984 – 1985
• Keywords: Liquid Phase Diffusion Welding / Amorphous Interlayers / Superalloy / Titanium and Titanium Alloys / ろう付

Research Abstract

Firstly, effects of the morphology and composition of nickel-base interlayers on transient liquid phase diffusion weldability of superalloy Inconel 713C have been investigated by microscopy, electron probe microanalysis and high temperature strength tests of the joints.
Proper composition adjustment, powder refinement and homogenization of the interlayers were indicated to be both important for the improvement of the weldability. Especially in amorphous interlayers made by the rapid quenching liquid metal method, the composition homogeneity which contributes to easy homogenization of the joints was fairly improved without segregation of molybdenum and hafnium. Additionally, in case of using amorphous interlayers, the thickness of liquid layer formed at the joint interface during welding was revealed to become thinner compared with the case of using powdered interlayers, so that the isothermal solidification of the liquid phase could occur more rapidly. These phenomena were demonstrated to result in increasing the joint strength, and some of the jionts showed 100 percent jiont efficiency in stress-rupture tests.
Secondly, the Liquid-phase diffusion weldability and brazability of commercial pure titanium and Ti-6A1-4V alloy has been investigated by microscopy, electron probe microanalysis and tensile tests at both room and high temperatures.
In order to prevent from changing the fine base metal structures, the titanium and Ti-6A1-4V joints were made below <beta> transformation and <beta> transus temperatures respectively, by use of newly developed amorphous interlayers with low melting points, consisting of Ti, Zr, Cu and Ni.
Both joints of titanium and Ti-6A1-4V made at 850゜C for 5 minutes and at 900゜C for 10 minutes respectively, were failed in base metal without changing of the base metal structures. This shows that in case of titanium and titanium alloys, enough joints to be comparable with base metals can be made by liquid phase diffusion welding with new Ti-Zr-Cu-Ni amorphous filler metals.