Tan Duo, Fu Bin, Guan Wei, Li Yu, Guo Yanhui, Wei Liqun, Ding Yi
School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, China.
Baowu Special Metallurgy Co., Ltd., Shanghai 200940, China.
Materials (Basel). 2023 Sep 20;16(18):6298. doi: 10.3390/ma16186298.
Multiple deformed substructures including dislocation cells, nanotwins (NTs) and martensite were introduced in super austenitic stainless steels (SASSs) by cryogenic rolling (Cryo-R, 77 K/22.1 mJ·m). With the reduction increasing, a low stacking fault energy (SFE) and increased flow stress led to the activation of secondary slip and the occurrence of NTs and martensite nano-laths, while only dislocation tangles were observed under a heavy reduction by cold-rolling (Cold-R, 293 K/49.2 mJ·m). The multiple precursors not only possess variable deformation stored energy, but also experience competition between recrystallization and reverse transformation during subsequent annealing, thus contributing to the formation of a heterogeneous structure (HS). The HS, which consists of bimodal-grained austenite and retained martensite simultaneously, showed a higher yield strength (1032 MPa) and a larger tensile elongation (9.1%) than the annealed coarse-grained Cold-R sample. The superior strength-ductility and strain hardening originate from the synergistic effects of grain refinement, dislocation and hetero-deformation-induced hardening.
通过低温轧制（Cryo-R，77 K/22.1 mJ·m）在超级奥氏体不锈钢（SASSs）中引入了包括位错胞、纳米孪晶（NTs）和马氏体在内的多种变形亚结构。随着压下率的增加，低堆垛层错能（SFE）和流动应力的增加导致二次滑移的激活以及NTs和马氏体纳米板条的出现，而在冷轧（Cold-R，293 K/49.2 mJ·m）的大压下率下仅观察到位错缠结。这些多种前驱体不仅具有可变的形变储能，而且在随后的退火过程中经历再结晶和逆转变之间的竞争，从而有助于形成异质结构（HS）。由双峰晶粒奥氏体和残余马氏体同时组成的HS显示出比退火态粗晶Cold-R样品更高的屈服强度（1032 MPa）和更大的拉伸伸长率（9.1%）。优异的强度-延展性和应变硬化源于晶粒细化、位错和异质变形诱导强化的协同效应。
