Microstructure characteristics, strengthening and toughening mechanism of rolled and aged multilayer TWIP/maraging steels

摘要

The multilayer structure design of steels can accomplish the purpose of strengthening and toughening. Multilayer TWIP/Maraging steel with high strength, high toughness and interfacial shear strength of 564 MPa is obtained by vacuum hot rolling, subsequent cold rolling and aging treatment. It is found that hot rolling can achieve effective interface bonding ability. Grain refinement, twinning proliferation and dislocation strengthening are generated in TWIP layers with the increase of cold rolling reduction, which can improve the strength and toughness of multilayer steel. However, when the reduction reaches more than 90%, the nanocrystalline and nano twins are appeared in TWIP layers, and plasticity is seriously reduced. The proper adjustment of the cold rolling and ageing process, interface alloying elements diffusion, twinning proliferation, nano-precipitation strengthening, and work hardening can obviously improve the interface bonding ability, strength and toughness, this research provides theoretical basis and experimental support for the lamination design and strengthening-toughening mechanism of a series of metal materials.