陈海龙,周雯,张绍龙,等.高应变速率对微纳结构贝氏体钢组织及力学性能的影响[J].精密成形工程,2025,17(4):138-149.
CHEN Hailong,ZHOU Wen,ZHANG Shaolong,et al.Effect of High Strain Rate on Microstructure and Mechanical Properties of Micro/nano-structured Bainitic Steel[J].Journal of Netshape Forming Engineering,2025,17(4):138-149. |
| 高应变速率对微纳结构贝氏体钢组织及力学性能的影响 |
| Effect of High Strain Rate on Microstructure and Mechanical Properties of Micro/nano-structured Bainitic Steel |
| 投稿时间：2024-09-30 |
| DOI：10.3969/j.issn.1674-6457.2025.04.014 |
| 中文关键词: 微纳结构贝氏体钢 拉伸变形 应变速率 残余奥氏体 相变诱发塑性效应 |
| 英文关键词: micro-nano structured bainitic steel tensile deformation strain rate retained austenite transformation induced plasticity effect |
| 基金项目:湖北省重大攻关项目(2023BAA019-4);国家自然科学基金(U20A20279，12072245，52071238) |
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| 中文摘要: |
| 目的 通过对高应变速率和准静态速率下微纳结构贝氏体钢的组织与力学性能进行研究，探明高应变速率下微纳结构贝氏体钢的强塑性机理，为推广微纳结构贝氏体钢等先进高强钢在高应变率工况下的应用提供一定的理论指导。方法 对微纳结构贝氏体钢进行准静态和高应变速率拉伸试验，利用扫描电镜(SEM)、电子背散射衍射(EBSD)及透射电镜(TEM)等试验方法对试验结果进行表征。结果 相较于准静态拉伸，试验钢在高应变速率拉伸条件下的延伸率大幅度提高，从6.7%提升至12.7%，但抗拉强度从1 665 MPa降低到1 553 MPa，屈服强度由1 088 MPa降低至1 070 MPa。高应变速率拉伸时，在真应变小于0.04阶段，绝热升温效应使断口附近组织软化程度加深，断口附近应力松弛，更有利于韧窝的形核和长大;当真应变超过0.04后，TRIP效应处于主导位置，更多的残余奥氏体转变为马氏体，试验钢在2种效应的共同作用下，塑性提高。高应变速率下的位错密度低于准静态拉伸的位错密度，这是由于在高应变速率拉伸过程中，贝氏体基体塑性变形程度较大，减少了与形变诱导马氏体之间的变形不相容，不需要产生额外的位错。结论 高应变速率拉伸后，微纳结构贝氏体钢中残余奥氏体含量大幅减小，贝氏体板条发生较大塑性变形，使强塑性提高。 |
| 英文摘要: |
| In order to explore the strength and plasticity mechanism of micro-nano structure bainitic steel under high strain rate, and provide some theoretical guidance for the application of advanced high strength steel such as micro-nano structured bainitic steel under high strain rate working conditions, the work aims to investigate the mirostructure and mechanical properties of micro-nano-structured bainitic steel under high strain rate and quasi-static rate. Uniaxial tensile tests were carried out at high strain rate and quasi-static rate to characterize the test results with scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and transmission electron microscopy (TEM) and other methods. Compared with quasi-static tensile, the elongation of the test steel under tensile condition at high strain rate greatly increased from 6.7% to 12.7%, but the tensile strength decreased from 1 665 MPa to 1 553 MPa, and the yield strength decreased from 1 088 MPa to 1 070 MPa. During the tensile at high strain rate, when the true strain was less than 0.04, the adiabatic heating effect exacerbated microstructural softening near the fracture. The softening of the microstructure near the fracture, along with stress relaxation, facilitated the nucleation and growth of toughening mechanisms. Once the true strain exceeded 0.04, the transformation induced plasticity (TRIP) effect became dominant, promoting further transformation of retained austenite into martensite, leading to enhanced overall plasticity through the combined effects of these mechanisms. The dislocation density under high strain rate was lower than that observed during quasi-static tensile, due to the more extensive plastic deformation of the bainite, which decreased incompatibility with deformation-induced martensite and minimized the need for additional dislocations. Following the tensile at high strain rate, the content of retained austenite in the micro-nano structured bainitic steel greatly decreases, and the bainite laths undergoes large plastic deformation, improving the strength and plasticity. |
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