The dependences of deformation temperature on the strain-hardening characteristics and fracture behavior of Mn–N bearing lean duplex stainless steel
The dependences of deformation temperature on the strain-hardening characteristics and fracture behavior of Mn–N bearing lean duplex stainless steel
复制标题
变形温度对Mn-N轴承贫双相不锈钢应变硬化特性和断裂行为的影响
DOI：
10.1016/j.msea.2021.141440
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Miao Jin
中科院分区：
文献类型：
--
作者：
Qixiang Jia;Yongxin Wang;Ruixue Mei;Lei Chen;Shuo Hao;Huanyu Zhang;Xiaocong Ma;Zongyuan Zou;Miao Jin
The tensile properties and fracture behavior of lean duplex stainless steel (LDSS) containing Mn–N was investigated through tensile deformation by varying the deformation temperature from 353 K to 213 K. The ultimate tensile strength (UTS) and yield strength (YS) of the test LDSS increased continuously as the temperature was lowered from 353 K to 213 K. The total elongation (TE) did not decline smoothly as the temperature decreased, instead, the TE peaked at the room temperature (293 K). This temperature-dependent mechanical response was mainly associated with the kinetics of strain-induced martensite transformation (SIMT) in the metastable austenite (γ). A quantitative kinetic model of temperature-dependent SIMT was established, which indicates a positive relationship that the lower the deformation temperature, the faster the SIMT rate. With respect to the nucleation of strain-induced martensite, three modes were clearly manifested by the nucleation mechanism during tensile deformation at different temperature ranges. The first case corresponded to the direct transformation of γ→α′ at 213 K. The second mode of γ→ε→α′ dominated the SIMT at the 213 K–293 K range. The α′-martensite nucleated at the mechanical twinning interactions at 293–333 K, i.e., γ→Twins→α’, which corresponded to the third mode. Notably, as the test temperature was lowered, a continuous fracture mechanism transition gradually emerges from fully ductile to brittle. Microstructural observations from in-situ tensile tests and EBSD showed that damages at the ferrite/martensite (α/α′) interface dominated at 293 K. At 213 K, besides the interfacial fractures that occurred at 293 K, cleavage-type fractures were also found inside ferrite and martensite. Void coalescence was mainly responsible for the ductile fractures over 353 K where SIMT was absent.
