Optimization of Plasticity and Toughness in 10.5Cr–1.5W–2.0Mn Ferritic/Martensitic Steel through Deep Cryogenic Processing

The effect of deep cryogenic treatment (DCT) on microstructure and mechanical properties of 10.5Cr–1.5W–2.0Mn ferritic/martensitic steel is studied. The results show that DCT has little effect on the hardness and strength of steels, while the plasticity and toughness of steels can be significantly influenced by DCT. An appropriate DCT process can greatly improve the plasticity and toughness of steels. The impact toughness and elongation of the steel through 2‐cycle DCT are 28.8 and 30.8% higher than the steel without DCT, respectively. The results of microstructure show DCT‐refined martensitic laths/blocks, reduced carbide size, increased carbide volume fraction, and increased dislocation density. The fine‐grain strengthening effect caused by the refinement of martensitic laths/blocks improves the plasticity and toughness of the steel, while the dislocation strengthening effect caused by the increase of dislocation density and the precipitation strengthening effect caused by the precipitation of fine carbides reduce the plasticity and toughness of the steel.