Heterogeneous grain structures with dual-nanoprecipitates have been designed and fabricated in a lightweight steel. The size and the volume fraction of coherent κ’–carbides are increased by aging treatment, while the volume fraction of B2 precipitates and the heterogeneous grain structure are nearly unchanged after aging treatment. The aged samples are found to have a better synergy of strength and ductility, as compared to the unaged samples. The better tensile properties in the aged samples can be owing to the higher hetero-deformation-induced hardening and the higher density of induced geometrically necessary dislocations during tensile deformation. Two distinct precipitation hardening mechanisms are revealed for the dual-nanoprecipitates, i.e., bypassing mechanism for B2 precipitates and shearing mechanism for coherent κ’–carbides. Numerous dislocations can be observed both around and inside coherent κ’–carbides. High density of stacking faults and nanotwins can also be found in the grain interiors of the aged samples, resulting in strong strain hardening by interaction between them and dislocations. The better tensile properties in the aged samples can also be attributed to the stronger shearing precipitation hardening effect by larger size and higher volume fraction of coherent κ’–carbides.

具有双纳米沉淀物的异质晶粒结构已在轻质钢中设计和制造。时效处理增加了共格κ'-碳化物的尺寸和体积分数，而时效处理后B2析出物的体积分数和异质晶粒结构几乎没有变化。与未老化的样品相比，老化的样品被发现具有更好的强度和延展性协同作用。老化样品中更好的拉伸性能可能是由于更高的异质变形诱导硬化和拉伸变形过程中诱导的几何必要位错的更高密度。对于双纳米沉淀物，揭示了两种不同的沉淀硬化机制，即 B2 沉淀物的绕过机制和相干 κ'-碳化物的剪切机制。在相干 κ'-碳化物周围和内部都可以观察到许多位错。在老化样品的晶粒内部也可以发现高密度的堆垛层错和纳米孪晶，通过它们和位错之间的相互作用导致强烈的应变硬化。老化样品中更好的拉伸性能也可以归因于更大尺寸和更高体积分数的相干κ'-碳化物的更强的剪切沉淀硬化效应。