In ultrahigh-strength maraging steels, nanoprecipitates increase yield strength increments with low work hardening, which is detrimental to their applications. In this study, core–shell nanoprecipitates were introduced to modulate strength, ductility, and work hardening in ultrahigh-strength stainless steel with a tensile strength of 2020 ± 23 MPa and uniform elongation of 9.0 % ± 0.9 %. The formation of core–shell nanoprecipitates and their effects on the work hardening of steel were systematically investigated. Evidently, a Ni3Ti core was encapsulated by a Mn-enriched shell with an ordered structure, which is coherent with the martensitic matrix. During deformation, the ordered Mn-enriched shells were disrupted by dislocation cutting, leading to an increase in structure distortion in the vicinity of the Ni3Ti cores. This promoted the multiplication of dislocations, thereby substantially improving work hardening and uniform elongation. The yield strength was primarily contributed by multiple nanoprecipitates, including the core–shell, α′-Cr, and Mo-rich precipitates.

中文翻译：

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核壳纳米析出物的形成及其对超高强度不锈钢加工硬化的影响


在超高强度马氏体时效钢中，纳米析出物以低加工硬化率增加屈服强度增量，这对其应用不利。在本研究中，引入了核壳纳米沉淀物来调节超高强度不锈钢的强度、延展性和加工硬化，抗拉强度为 2020 ± 23 MPa，均匀伸长率为 9.0 % ± 0.9 %。系统研究了核壳纳米析出物的形成及其对钢加工硬化的影响。显然，Ni3Ti 芯被富含 Mn 的壳层封装，该壳层具有有序结构，与马氏体基体相一致。在变形过程中，有序的富含 Mn 的壳层被位错切割破坏，导致 Ni3Ti 核附近的结构变形增加。这促进了位错的倍增，从而大大改善了加工硬化和均匀伸长率。屈服强度主要由多种纳米沉淀物贡献，包括核壳、α′-Cr 和富含 Mo 的沉淀物。