Microstructure and phase analysis of brazing bonds for stainless steel (AISI 316L and 431) to carbon steel (A516 G70) using a Ni–Si–B filler metal alloy

Abstract

Abstract Investigation the mechanism of brazing stainless steels (Austenitic stainless steel type 316L and martensitic stainless steel type 431) similar and dissimilar and also brazing them with carbon steel type A516 grade 70 to see the difference in bonding phases, the five specimen were brazed with Ni base filler metal with (4.5% Si and 3.2% B) using a furnace with protected gas (pure Argon) at constant holding time 10 min. The optical and scanning electron microscopy (SEM) are used to study the joint microstructure, also the interdiffusion of the elements was examined by energy dispersive spectroscopy analysis (EDS). While the reaction phases are identified by x-ray diffraction (XRD). The brazed joints showed continuous bonding between the filler alloy and the substrate, indicating to good wetting between the surfaces. EDS line and mapping scan shows The Nickel element which it’s at the filler metal alloy will be goes into the interface almost, because the stainless steels sides can handle it, also Cr element. While Si element will concentrate at the bond zone, finally Fe element Transfer through brazing zones easy. XRD test reveals that the bonding zone of the five specimen shows more the six types of phases which are Ni-Cr-Fe, Cr-Ni-Fe-C, SiC, Fe2B, Cr2B, and Cr-Fe-Ni-Mo.