Investigation of the effect of alkaline environment on mechanical properties of additively manufactured 17-4 PH Stainless Steel parts produced using recycled metal powder.

Abstract

Metal additive manufacturing (AM) has shown its advantages over conventional manufacturing methods in producing complex components. Re-usage of metal powder after completion of the AM process for the next batch of the manufacturing cycle is one of the ways to make AM more cost-effective and environmentally friendly. 17–4 precipitation hardening stainless steel (17–4 PH) offers corrosion resistance, high strength, and toughness making it a widely used AM material. Recycling of metal powder in AM has inherent impacts on materials’ performances. Such practice makes it imperative to fully comprehend the performances of AM parts produced by re-used metal powder. In the current research, the authors have performed an investigation of the effect of alkaline environment on the mechanical properties of additively manufactured 17–4 PH parts produced using recycled metal powder. This study is conducted due to the lack of scientific knowledge in this area. The authors performed immersion testing of recycled powder-produced 17–4 PH parts in aqueous alkaline solution and subsequently conducted weight loss analysis, tensile testing, hardness testing and microstructural analysis. Results of mechanical properties were also compared with those of the as-built recycled and virgin powder produced 17–4 PH AM parts. The findings of the present study indicated changes in the weight, tensile strength, ductility, hardness, and morphology of the recycled AM parts after subjected to alkaline environment. These changes in material performance and morphology could be owing to the reaction to the corrosive effects of active hypochlorite ion (OCl–) present in alkaline solution.