Influence of deep rolling at different temperatures on near-surface and mechanical properties of a Maraging C250 steel

Abstract

• Conventional aging (3 h at 480 °C) leads to high strength and pronounced ductility. • Influence of deep rolling on a Maraging steel is investigated for the first time. • Integration of an aging treatment into deep rolling process reveals great potential. • Combined process leads to pronounced compressive residual stresses. • Short-term heat treatments can further improve the near-surface properties. Due to an outstanding combination of high strength and fracture toughness Maraging steels are used in numerous industries, e.g., in the aerospace sector. The high strength can be attributed to precipitation strengthening by conventional age-hardening heat treatments. However, as many of the envisaged applications will suffer from cyclic loadings, the fatigue properties are of significant interest in terms of a reliable use. Generally, Maraging steels are characterized by a relatively low fatigue strength limiting the use in certain applications. In this context, mechanical surface treatment processes are promising candidates to overcome these challenges. In particular, deep rolling represents a suitable process, as it is known for increased depth effects as well as smoother surface profiles compared to other mechanical surface treatment processes. Moreover, aging heat treatments can easily be implemented into the process. Accordingly, the present study focuses on near-surface and mechanical properties of a Maraging C250 steel after deep rolling. Characterization of the near-surface area was conducted by X-ray diffraction and hardness measurements. Mechanical properties were assessed by tensile and fatigue tests. The results presented reveal a great potential of the integration of an aging heat treatment into the deep rolling process eventually leading to significant process time reduction.

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