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We studied the compressive-tensile yield asymmetry (CTYA) and its sensitivity to standard post-processing treatments for a 17-4 PH stainless steel processed with selective laser melting (SLM). Quasistatic tensile and compression tests at ambient temperatures reveal a consistent CTYA for all tested conditions, with compressive yield strengths exceeding tensile values. In the as-printed state, yield asymmetry (Δσ) is ∼113 MPa. Stress-relieving at 300 °C results in only a marginal decrease in asymmetry (Δσ ∼109 MPa), suggesting that the residual stresses generated during SLM have a negligible effect on the observed CTYA. Our analyses indicate that “dynamic softening” due to a stress-assisted austenite-to-martensite transformation governs the yield behavior similar to that observed in transformation-induced plasticity (TRIP)-assisted steels containing mechanically unstable retained austenite. This interpretation is further supported by the increased asymmetry, Δσ ∼127 MPa, observed in a solution-treated and aged specimen, which has a slightly higher retained austenite volume fraction (24 % vs. 21 %). Direct aging at 482 °C of the as-printed steel with a ferritic microstructure causes severe embrittlement. Brittle fracture occurs under tensile stresses well below the yield strength. This pronounced loss of ductility most likely arises from a strong <001> fiber texture along the build direction developed during SLM, which is known to promote cleavage-type fracture on {001} planes. A solution treatment at 1000 °C for 1 h, austenitizes the microstructure completely, and subsequent quenching produces a predominantly martensitic structure with a much weaker crystallographic texture, which restores a favorable strength-ductility balance after aging. 

Abstract The feasibility of using argon‐atomized QT 17‐4+ stainless steel powder for directed energy deposition (DED) additive manufacturing is studied. The QT 17‐4+ steel is a novel martensitic steel designed based on the compositional modification of the standard 17‐4 precipitation‐hardened (PH) stainless steel. This modification aims to achieve better mechanical properties of as‐deposited components compared to the heat‐treated wrought 17‐4PH steel. In this study, QT 17‐4+ steel powder is used for DED, for the first time. The influence of laser power, laser scan speed, powder feed rate, and hatch overlap on the density is studied. The central composite design is used to determine the experimental matrix of these factors. The response surface methodology is used to obtain the empirical statistical prediction model. Both columnar and equiaxed parent austenite grain structures are observed. X‐ray diffraction analyses reveal a decrease in the percentage of retained austenite from 19% in the powder to 5% after DED. The microhardness of the DED processed sample in the as‐deposited state is slightly higher than that of wrought 17‐4PH steel either solution‐annealed or H900‐aged. A higher 0.2% yield strength, a lower ultimate tensile strength, and lower elongation are observed for the vertically printed test sample, when compared to the horizontal one.