Microstructures and Mechanical Properties of a New As-Hot-Rolled High-Strength DP Steel Subjected to Different Cooling Schedules
Microstructures and Mechanical Properties of a New As-Hot-Rolled High-Strength DP Steel Subjected to Different Cooling Schedules
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DOI：
10.1007/s11661-013-1839-z
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发表时间：
2013-06
期刊：
影响因子：
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通讯作者：
Jun Hu;L. Du;Jianjun Wang;Cai-ru Gao;Tong Yang;A. Wang;R. Misra
中科院分区：
文献类型：
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作者：
Jun Hu;L. Du;Jianjun Wang;Cai-ru Gao;Tong Yang;A. Wang;R. Misra
对一种低碳双相钢进行了控轧控冷试验，研究了其显微组织和力学性能。研究了空冷温度和卷取温度等冷却制度对双相钢最终组织和力学性能的影响。并对沉淀行为和屈强比进行了讨论。研究表明，它是可能的，以获得780 MPa和22%的拉伸强度和伸长率，分别在两个冷却时间表调查。当进行中等空冷和低温卷取时，显微组织由90%的铁素体和10%的马氏体组成，使得屈强比为低的0.69。当钢直接冷却到卷取温度时，其组织由75%的铁素体和25%的粒状贝氏体组成，具有0.84的高屈强比。与常规双相钢相比，高屈服强度归因于纳米TiC颗粒诱导的沉淀硬化和高Si含量的固溶强化。界面相析出物在合适的台阶移动率下形成，且排间距随铁素体转变速率而变化。由于铁素体晶界的生长方向不同，同一晶粒内的晶粒间存在着不同的取向，由于两种取向的竞争机制，两种晶粒间的界面上没有析出相。
Controlled rolling followed by accelerated cooling was carried out in-house to study the microstructure and mechanical properties of a low carbon dual-phase steel. The objective of the study described here was to explore the effect of cooling schedule, such as air cooling temperature and coiling temperature, on the final microstructure and mechanical properties of dual-phase steels. Furthermore, the precipitation behavior and yield ratio are discussed. The study demonstrates that it is possible to obtain tensile strength and elongation of 780 MPa and 22 pct, respectively, at the two cooling schedules investigated. The microstructure consists of 90 pct ferrite and 10 pct martensite when subjected to moderate air cooling and low temperature coiling, such that the yield ratio is a low 0.69. The microstructure consists of 75 pct ferrite and 25 pct granular bainite with a high yield ratio of 0.84 when the steel is directly cooled to the coiling temperature. Compared to the conventional dual-phase steels, the high yield strength is attributed to precipitation hardening induced by nanoscale TiC particles and solid solution strengthening by high Si content. The interphase precipitates form at a suitable ledge mobility, and the row spacing changes with the rate of ferrite transformation. There are different orientations of the rows in the same grain because of the different growth directions of the ferrite grain boundaries, and the interface of the two colonies is devoid of precipitates because of the competitive mechanisms of the two orientations.