Enhanced stretch flangeability and crack propagation behavior of an 1100 MPa grade TRIP-aided bainitic ferrite steel
Enhanced stretch flangeability and crack propagation behavior of an 1100 MPa grade TRIP-aided bainitic ferrite steel
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DOI：
10.1016/j.jmrt.2023.08.226
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发表时间：
2023-08
期刊：
影响因子：
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通讯作者：
Yuan Wang;Yunbo Xu;Yu Wang;Jia-yun Zhang;C. Guo;Xu Wang;Wenzhu Zhao;Hongliang Liu
中科院分区：
文献类型：
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作者：
Yuan Wang;Yunbo Xu;Yu Wang;Jia-yun Zhang;C. Guo;Xu Wang;Wenzhu Zhao;Hongliang Liu
为了应对汽车工业对轻量化、安全性和减排的挑战，通过控制贝氏体铁素体的大小和形状，制备了相变诱发塑性辅助贝氏体铁素体(TBF)钢，并与淬火和分凝(Q&P)钢进行了比较。通过膨胀测试和显微组织表征，分析了贝氏体相变对力学性能、微孔洞形成和裂纹扩展的影响。在较低的等温贝氏体相变(IBT)温度下，板条贝氏体基体可以防止裂纹的形成，限制裂纹在板条内部的扩展，有利于同时提高强度和拉伸翻边性能。此外，粒状贝氏体、粗大马氏体岛和奥氏体岛在较高的IBT温度下会增加空洞形成的风险。这些空洞为裂纹的形成提供了初始位置，这也是导致孔洞扩展率(HER)降低的原因。结果表明，T-375具有优异的力学性能，其HER为33.5%，总延伸率为16.9%，抗拉强度为1191áMpa，屈服强度为934áMpa。
In order to face the challenges of lightweight, safety, and emission reduction in the automotive industry, transformation-induced plasticity aided bainitic ferrite (TBF) steel was fabricated by controlling the size and shape of bainitic ferrite and compared with quenching and partitioning (Q&P) steels. The effects of bainite transformation on the mechanical properties, microvoid formation, and crack propagation were analyzed by dilatometry measurement and microstructure characterization. At lower isothermal bainite transformation (IBT) temperature, the lathy bainitic matrix can prevent crack formation and limit the crack propagation inside its laths, in favor of improving the strength and stretch flangeability simultaneously. In addition, granular bainite, coarse martensite, and austenite (M-A) islands would increase the risk of void formation at higher IBT temperatures. These voids provided the initial sites for crack formation, which was also responsible for the reduction of the hole expansion ratio (HER). In conclusion, the outstanding properties were achieved in the T-375 samples with the HER of 33.5%, the total elongation of 16.9%, the tensile strength of 1191áMPa, and the yield strength of 934áMPa.