He Changwei, Shen Yongfeng, Xue Wenying, Fan Zhijian, Zhou Yiran
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
The State Key Lab of Rolling & Automation, Northeastern University, Shenyang 110819, China.
Nanomaterials (Basel). 2024 Dec 30;15(1):48. doi: 10.3390/nano15010048.
High-performance lightweight materials are urgently needed because of energy savings and emission reduction. Here, we design a new steel with a low density of 6.41 g/cm, which is a 20% weight reduction compared to the conventional steel. The mechanical properties and microstructures of the steels prepared with different routes are systematically explored by utilizing uniaxial tensile testing and transmission electron microscopy. The steel processed by cold rolling and recrystallization annealing at 950 °C for 15 min shows an ultra-high yield strength of 1241 ± 10 MPa, while retaining a good ductility of 38 ± 1%. The high yield strength is mainly related to the synergistic precipitation strengthening introduced by nanoscale B2 and κ'-carbides. It is encouraging to notice that the yield strength increased without scarifying ductility, compared to the ST steel. The key reason is that the high strain hardening rate is activated by combined factors, including the blockage of numerous twins and nanoscale B2 to the dislocation movements, and dynamic slip band refinement. This study is instructive for concurrently enhancing the strength and ductility of austenitic lightweight steels with fully recrystallized grains and dual nano-precipitates.
由于节能减排的需求，高性能轻质材料亟待开发。在此，我们设计了一种新型钢，其密度低至6.41 g/cm，相较于传统钢材减重20%。通过单轴拉伸试验和透射电子显微镜，系统研究了不同制备工艺所得钢材的力学性能和微观结构。经冷轧及950 °C 15分钟再结晶退火处理的钢材，展现出1241 ± 10 MPa的超高屈服强度，同时保持38 ± 1%的良好延展性。高屈服强度主要归因于纳米级B2和κ'-碳化物引发的协同析出强化。值得注意的是，与ST钢相比，该钢材在不牺牲延展性的情况下提高了屈服强度。关键原因在于，众多孪晶和纳米级B2对位错运动的阻碍以及动态滑移带细化等综合因素激活了高应变硬化率。本研究对于同时提高具有完全再结晶晶粒和双纳米析出物的奥氏体轻质钢的强度和延展性具有指导意义。
