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以一种高锰奥氏体孪晶诱发塑性(TWIP)钢为实验材料, 采用700~1000 ℃保温20 min及800 ℃保温10~30 min的退火工艺获得了不同晶粒尺寸分布及晶界特征分布的再结晶组织, 结合EBSD技术及动电位极化曲线测试, 研究了晶粒度、晶粒均匀性及晶界特征分布对该钢抗腐蚀能力的影响. 结果表明, 该高锰奥氏体TWIP钢的抗腐蚀能力受组织中的晶粒度及重位点阵(CSL)晶界分布比例的影响, 二者的作用在再结晶的组织中因组织的均匀性不同而表现出明显差异. 当再结晶过程刚刚结束, 晶粒组织尚不均匀且未进入晶粒长大阶段时, 平均晶粒尺寸对抗腐蚀能力的影响占主导地位. 随着平均晶粒尺寸的增大, 该TWIP钢的抗腐蚀能力下降. 而当再结晶晶粒充分长大且晶粒尺寸分布均匀, CSL晶界所占的比例对其抗腐蚀能力的影响尤为显著. 随着CSL晶界所占晶界比例的提高, 该TWIP钢的抗腐蚀能力增加.

A considerable researches have been conducted to provide rather compelling evidence that the grain size and grain boundary distribution possess much influential effect on mechanical properties and corrosion behaviors in most metals and alloys. However, the effects of grain size and grain boundary distribution on anti-corrosion ability of materials have been independently studied. Some investigations indicate that the occurrence frequency and distribution characteristic of twin-related (especially Σ3n coincidence site lattice (CSL)) grain boundaries play a particularly important role in optimization of grain boundary character distribution. Unfortunately, both of these factors are interactive in annealing processes and there is a need to identify the independent role of the factors in anti-corrosion ability. In this work, a high manganese austenitic twinning-induced plasticity (TWIP) steel was used as experimental material and the anti-corrosion behavior of this steel resulted from both the grain size and grain boundary distribution was studied. The cold-rolled high manganese austenitic TWIP steel sheet was annealed at 700~1000 ℃ for 10~30 min to obtain microstructure with various grain sizes and CSL grain boundaries. The average grain size and grain boundary distribution characteristics for all the annealed steel sheets were obtained by the online analysis of EBSD data with HKL-Channel software. The anodic polarization curves were measured using CorrTest4 electrochemical workstation in 3.5%NaCl solution at 25 ℃ with a scan rate of 0.5 mV/s. The results show that both of the grain size and the occurrence frequency of CSL grain boundary caused by the uniformity of recrystallized microstructure have much effect on the anti-corrosion ability of this high manganese TWIP steel. When the recrystallization process just finished, and grains were inhomogeneous and not start to grow, the average grain size has a great influence on anti-corrosion ability. With increasing the grain size, the anti-corrosion ability of this high manganese TWIP steel was weakened. When the recrystallized grain growth fully takes place, the occurrence frequency of CSL grain boundary has the dominant effect on the anti-corrosion ability. The anti-corrosion ability was optimized with increasing the frequency of CSL grain boundary.