Element distribution mapping and microhardness analysis of stainless steel-copper braze joint produced by copper-based BFM

Abstract EN

The brazing of copper with stainless steel (SUS304 SS) has been performed by using a copper-based brazing filler metal (BFM: VZ2250), under an argon gas atmosphere in a brazing furnace.

The brazing experiments were conducted at temperatures in the range of 640-680 °C for the time durations in the range of 5-15 min.

Material’s chemistry of brazed samples has been studied by energy dispersive spectroscopy (EDS) system linked with a Phenom Pro X scanning electron microscope (Phenom Pro SEM).

This study enables us to analyze the elemental distribution/mapping within the brazed samples.

It has been found that Ni atoms from the BFM diffused into SUS304 SS owing to the better solubility of Ni in Fe (substitutional solid solubility) than that of Cu in Fe.

A low Sn at.

% was observed in the EDS image for BFM region; this elemental distribution has been attributed to the possibility of reaction of Sn with Fe to form an intermetallic compound: FeSn2.

The spatial distribution of various elements has been studied by mapping analysis by using SEM-EDS technique for a brazed sample that showed the penetration depth of Ni and P to SUS304 and Cu regions.

It has also been shown that Fe and Cr slightly diffused in the brazed region.

Microhardness measurements at various locations of the brazed sample have been made and analyzed.

The microhardness data has been compared with literature and discussed accordingly.