孪晶诱导塑性钢的非均匀形变研究
Study of non-uniform deformation in twin-induced plasticity steel
Received:January 09, 2019  Revised:January 31, 2019
DOI:10.7520/1001-4888-19-007
中文关键词:  TWIP钢  原位EBSD  数字图像相关(DIC)  非均匀性
英文关键词:TWIP steel  in-situ EBSD  Digital image correlation (DIC)  non-uniformity
基金项目:中国国家重点研发计划(2017YFB0702002)资助
Author NameAffiliation
CHEN Yue Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, Sichuan, China 
LI Chao Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, Sichuan, China 
ZHONG Zheng-ye* Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, Sichuan, China 
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中文摘要:
      通过原位电子背散射衍射(EBSD, Electron backscatter diffraction)和数字图像相关(DIC, Digital image correlation)技术,对孪晶诱导塑性(TWIP, Twinning induced plasticity)钢拉伸过程中的非均匀形变进行研究。结果发现,拉伸应变不均匀,应变集中于高角度晶界与大晶粒内部。滑移带的开启并不完全遵从斯密特(Schmid)定律,且滑移带与晶界作用明显。非均匀变形导致晶粒的取向梯度增大。研究表明,TWIP钢在拉伸过程中,出现明显非均匀形变现象,非均匀程度随着变形的增大而降低,且降低速率逐渐减小,应变超过12%后非均匀程度趋于稳定,但其值相对较大导致TWIP钢在应变较大时(15%),非均匀变形现象依然明显。滑移带容易在高角度晶界处产生集中,在低角度的晶界处穿过晶界。晶粒内各区域不同的变形量造成晶格朝不同方向旋转,或者朝同一方向旋转不同的角度而形成较大的取向差,且随着应变的增加而增加。非均匀变形主要是由斯密特因子(Schmid factor, SF)的大小、晶粒内滑移带可滑移的长度、滑移带间的相互作用和晶界对滑移带阻碍强度等因素共同影响。
英文摘要:
      In-situ electron backscatter diffraction (EBSD) and digital image correlation (DIC) methods are used to study the inhomogeneous deformation during tensile loading of a twinning-induced plasticity (TWIP) steel. The results show that the tensile strain is inhomogeneous, and the strain concentration occurs at the high-angle grain boundaries and in the interior of large grains. The activation of the slip bands does not completely follow the Schmid law, and the slip bands interact with the grain boundaries significantly. The inhomogeneous deformation results in the increase of grain orientation gradient. The studies show that during the tensile loading process, the TWIP steel exhibits an obviously inhomogeneous deformation phenomenon and the degree of inhomogeneity decreases with deformation increasing, but the decreasing rate goes down gradually. The degree of inhomogeneity tends to be stable when the strain is larger than 12%. The inhomogeneity degree value is relatively large, making the inhomogeneous deformation still obvious when the strain is large (15%). Slip bands are prone to concentrate at high-angle grain boundaries, and they tend to penetrate the low-angle grain boundaries. The different deformation amounts at various regions of grains make the lattice to rotate towards different directions or towards one direction with different rotation angles, thereby forming a large disorientation which increases with the strain increasing. The inhomogeneous deformation is mainly influenced by the value of Schmid Factor (SF), the slipping length of slip bands in a grain, the interaction among slip bands, and the grain boundary blocking strength on slip bands.
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