Effect of microstructure evolution on Luders strain and tensile properties in an intercritical annealing medium-Mn steel
作者机构：Collaborative Innovation Center of Steel TechnologyUniversity of Science and Technology BeijingBeijing 100083China Beijing Laboratory for Modern Transportation Advanced Metal Materials and Processing TechnologyUniversity of Science and Technology BeijingBeijing 100083China Carbon Steel and Thin Slab Factory of Hongxing Iron and Steel Co.Ltd.Jiuquan Iron and Steel GroupJiayuguan 735100GansuChina
出 版 物：《Journal of Iron and Steel Research(International)》 (钢铁研究学报（英文版）)
年 卷 期：2021年第28卷第6期
页 面：762-772页
核心收录：
学科分类：08[工学] 0806[工学-冶金工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 0801[工学-力学（可授工学、理学学位）] 0702[理学-物理学]
基 金：the support of the National Key Research and Development Program of Thirteenth Five-Year Plan Period(Grant No.2017YFB0304400) the National Natural Science Foundation of China(Grant No.51574028).
主 题：Luders strain Medium-Mn steel Work hardening Dislocation Mechanical property
摘 要：The influence of microstructural characteristics on Lu¨ders strain and mechanical properties was explored by means of altering thermo-mechanical circumstances in an intercritical annealing(IA)medium-Mn Fe-11Mn-0.09C-0.25Si(wt.%)steel.By IA of cold-rolled samples with severe plastic deformation,exclusively equiaxed dual phases were obtained because of active recovery and recrystallization.The equiaxed austenite(gamma E)with a larger size and inadequate chemical concentration was more readily transformed into martensite,and subsequent transformation-induced plasticity(TRIP)effect was triggered actively at relatively higher IA temperature,lessening localized deformation.In addition,grown-in dislocations were prone to multiply and migrate around a broad mean free path for coarser equiaxed ferrite(alpha E)due to weakening dynamic recovery;therefore,it was the ensuing increased mobility of dislocations instead of reserving plentiful initial dislocation density that facilitated the propagation velocity of Luders bands and the accumulation of work hardening.In contrast,the bimodal-grained microstructure with lath-like and equiaxed austenite(gamma L+gamma E)satisfactorily contributed to a smaller yield point elongation(YPE)without compromise of comprehensive mechanical properties on the grounds that austenitic gradient stability gave rise to discontinuous but sustainable TRIP effect and incremental work hardening.Hence,Luders strain is closely related to the absence of work hardening in the region which yields locally.It follows that the decreased stability of retained austenite,favorable mobility of dislocations and the bimodal-grained structure all prominently make up for the insufficiency of work hardening,thereof resulting in a limited YPE.
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