Microstructure and phase constituents near the fusion zone of Fe 3Al/Cr–Ni alloys joints produced by MAW

Abstract

A series of Cr–Ni alloys were deposited on the Fe 3Al surface by manual arc welding (MAW) technology to study the weldability of this intermetallic. The results indicated that Fe 3Al performed bad weldability for Cr18–Ni8 and Cr18–Ni13 alloys but good for Cr25–Ni13 alloy. Subsequently, the microstructural morphology, elements distribution and phase constituents near the fusion zone of Fe 3Al/Cr25–Ni13 alloys joints were analysed by means of metalloscope, SEM, EPMA and XRD. The matrix of Cr25–Ni13 surface layer was austenite (A). The pro-eutectoid ferrite (PF), upper and lower bainite (UB and LB), lath martensite (LM) and tiny dispersed carbide distributed on the austenitic grain boundaries as well as grains inside. There distributed some Al 2O 3 tiny granules near the fusion zone, contributing to the non-equilibrium nucleation of fine fusion zone grains. The phase constituents near the fusion zone were Fe 3Al, FeAl, Fe 2Al 5, γ-(Fe, C), γ-(Fe, Ni), NiAl, an Fe–C compound and the Fe–Cr–C compound (Cr 9Fe) 7C 3.