The Microstructural Evolution of Vacuum Brazed 1Cr18Ni9Ti Using Various Filler Metals.

Yunxia Chen,Fenggui Lu,Haichao Cui,Binfeng Lu

doi:10.3390/ma10040385

Yunxia Chen, Fenggui Lu + Show 2 more

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https://doi.org/10.3390/ma10040385

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Abstract

The microstructures and weldability of a brazed joint of 1Cr18Ni9Ti austenitic stainless steel with BNi-2, BNi82CrSiBFe and BMn50NiCuCrCo filler metals in vacuum were investigated. It can be observed that an interdiffusion region existed between the filler metal and the base metal for the brazed joint of Ni-based filler metals. The width of the interdiffusion region was about 10 μm, and the microstructure of the brazed joint of BNi-2 filler metal was dense and free of obvious defects. In the case of the brazed joint of BMn50NiCuCrCo filler metal, there were pits, pores and crack defects in the brazing joint due to insufficient wettability of the filler metal. Crack defects can also be observed in the brazed joint of BNi82CrSiBFe filler metal. Compared with BMn50NiCuCrCo and BNi82CrSiBFe filler metals, BNi-2 filler metal is the best material for 1Cr18Ni9Ti austenitic stainless steel vacuum brazing because of its distinct weldability.

Highlights

Well-developed joining process can promote the application of these alloys, but can provide designers with a versatile choices of materials
The base metal 1Cr18Ni9Ti austenitic stainless steel used in this study has a nominal composition of Cr 17~19 wt %, Ni 8~11 wt %, Ti 5 wt %, C less than 0.12 wt %, Si less than 1 wt %, Mn less than 2 wt %, the main other element is Fe
Fe and Cr diffused from 1Cr18Ni9Ti steel to the brazed region while Ni and Si diffused in the opposite direction

Summary

Introduction

Well-developed joining process can promote the application of these alloys, but can provide designers with a versatile choices of materials. Brazing is a process in which two or more closely fitting parts are joined via an intermediate metallic material (a brazing metal or alloy) which melts, the surface being joined is wetted, and it reacts and solidifies [4]. The brazing quality is influenced by many factors including brazing temperature [7], filler metal [8], holding time [9], cooling rate [10], etc. Among these various factors, using a reasonable brazing filler metal is one of the key features of the vacuum brazing process

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