Microstructure and hot corrosion performance of stainless steel 347 produced by wire arc additive manufacturing

Abstract

The present work reports the feasibility of wire arc additive manufacturing (WAAM) process to manufacture SS 347 components for high temperature applications. The microstructure of WAAM processed SS 347 (WAAM 347) comprised of austenite and residual delta-ferrite while the ferrite fraction varied between 1.40 and 4.20% along the building direction. Cyclic hot corrosion behaviour of WAAM 347 specimens were investigated under the Na2SO4-60%V2O5 molten salt at 700 degrees C by measuring the weight change. Higher weight gain was noticed in the samples exposed to hot corrosion because of the deposition of molten salt mixture. X-ray diffraction results revealed the formation of oxides like Fe2O3, FeV2O4, and Ni3V2O8 while the presence of NiCr2O4 and Cr2O3 lowers the corrosion rate at elevated temperatures. The absence of spallation due to the good adherence of oxide-scales highlights that WAAM 347 structures are suitable for elevated temperature applications.