Fabrication of AISI 434L Stainless Steel Thin Wall Structures by TIG-Aided Powder Bed Fusion Arc Additive Manufacturing: Evaluation of Metallurgical Characteristics and Mechanical Properties

Abstract

Thin wall structure with five-layer depositions has been fabricated by TIG-based powder bed fusion-type arc additive manufacturing (TIG PBF-AAM) method using AISI 434L stainless steel powder as feedstock. Suitable processing conditions were identified from the trial experiments of single-layer deposition, and thereafter multilayer depositions were executed to attain a thin wall structure. The effect of the processing conditions on the part geometry has also been investigated. Microstructural analysis revealed that the fabricated structure is dominated with α-ferrite phase along with martensite present mostly at the grain boundaries. Microhardness value in the fabricated part was recorded within a range of 186-330 HV_0.05, which is marginally higher than the hardness value of wrought AISI 434L steel. The analysis also shows development of compressive residual stress in the fabricated structure predominantly caused by the complex heating and cooling cycle experienced during the TIG arc scanning. The present study established the potential of TIG PBF-AAM method in the fabrication of a layered structure using metallic powder as feedstock.