Heat treatment, microstructure and mechanical properties of a C–Mn–Al–P hot dip galvanizing TRIP steel
Heat treatment, microstructure and mechanical properties of a C–Mn–Al–P hot dip galvanizing TRIP steel
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DOI：
10.1016/j.msea.2016.07.119
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发表时间：
2016-09
期刊：
影响因子：
6.4
通讯作者：
W. Ding;P. Hedström;Yan Li
中科院分区：
文献类型：
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作者：
W. Ding;P. Hedström;Yan Li
在Gleeble 3500实验室设备上对化学成分为0.20C-1.50Mn-1.2Al-0.07P(质量分数)的热镀锌TRIP钢进行了热处理。通过改变热处理工艺参数，研究了临界点温度、等温贝氏体转变温度和时间对合金组织和性能的影响。用扫描电子显微镜、透射电子显微镜和X射线衍射仪研究了材料的微观结构，并通过拉伸试验评价了材料的力学性能。此外，为了更好地了解热处理过程中的相变，进行了膨胀试验。热处理后获得了含有铁素体、贝氏体、残余奥氏体和马氏体的理想组织。进一步发现，IBT是决定钢的力学性能的关键，因为它控制着贝氏体量。随着贝氏体量的增加，残余奥氏体量增加，马氏体量减少。该钢的力学性能优异，抗拉强度超过780 Mpa(1例除外)，延伸率超过22%。
Heat treatments of a hot dip galvanizing TRIP (Transformation induced plasticity) steel with chemical composition 0.20C-1.50Mn-1.2Al-0.07P(mass%) were performed in a Gleeble 3500 laboratory equipment. The heat treatment process parameters were varied to investigate the effect of intercritical annealing temperature as well as isothermal bainitic transformation (IBT) temperature and time, on the microstructure and the mechanical properties. The microstructure was investigated using scanning electron microscopy, transmission electron microscopy and x-ray diffraction, while mechanical properties were evaluated by tensile testing. Furthermore, to generate a better understanding of the phase transformations during heat treatment, dilatometry trials were conducted. The desired microstructure containing ferrite, bainite, retained austenite and martensite was obtained after the heat treatments. It was further found that the IBT is critical in determining the mechanical properties of the steel, since it controls the fraction of bainite. With increasing bainite fraction, the fraction of retained austenite increases while the fraction of martensite decreases. The mechanical properties of the steel are excellent with a tensile strength above 780 MPa (expect in one case) and elongation above 22%.