Optimisation of precipitation hardening for 15-5 PH martensitic stainless steel produced by wire arc directed energy deposition

Abstract

This paper discusses directed energy deposition of 15-5 PH, which was successfully tailored with precipitation hardening (PH) to achieve the desired properties. Parametric analysis of solution annealing and aging at various time and temperature combinations was performed. Material characterisation was done in the as-deposited, solution annealed, and PH states. Investigations included microscopy, SEM/EDS, fractography, hardness, tensile, and impact toughness test. The as-deposited microstructure was composed of martensite laths along with delta ferrite. Optimisation of solution annealing was mandatory to achieve homogeneous austenite, which allowed PH. PH resulted in similar properties compared to conventionally produced steel. Peak aging resulted in 450 HV10 and an Rm of 1350 MPa, while the over-aged condition resulted in an impact toughness of over 77 J/cm2.