锻压技术

终轧温度对热轧双相钢DP580组织及性能影响

英文标题：Influence of finishing rolling temperature on microstructure and property for hot-rolled dual phase steel DP580

单位：首钢集团有限公司技术研究院绿色可循环钢铁流程北京市重点实验室北京首钢股份有限公司

分类号：TG335.35

出版年,卷(期):页码：2019,44(6):188-192

摘要：

通过光学显微镜、疲劳实验机和拉伸实验机等设备，以首钢热轧双相钢DP580为研究对象，研究了两种典型终轧温度对其组织、拉伸性能、疲劳性能的影响。结果表明：不同终轧温度导致铁素体尺寸、马氏体含量及形态存在明显差异。终轧温度升高，铁素体尺寸显著增加，马氏体呈现岛状，体积分数较高但形状不规则且多棱角；终轧温度降低，铁素体晶粒尺寸较小且含量较高，马氏体岛弥散均匀分布。对比力学性能发现，不同终轧温度下DP580钢的屈服强度差别较大，认为高终轧温度时产生的较大尺寸铁素体可导致屈服强度偏低。对比应力疲劳S-N曲线发现，高温终轧时DP580钢疲劳寿命较低，认为铁素体尺寸较大以及形状不规则、且多棱角的马氏体岛加速了裂纹的萌生及扩展。

For shougang hot-rolled dual phase steel DP580, the influences of two typical finishing rolling temperatures on its microstructure, tensile properties and fatigue properties were studied by optical microscope, fatigue testing machine, tensile testing machine and others. The results show that the grain size of ferrite, content and morphology of martensite significantly change at different finishing rolling temperatures. When the finishing rolling temperature increases, the grain size of ferrite significantly increases, and the martensite is island-shaped with the high volume fraction, the irregular shape and the multiple corners. However, when the finishing rolling temperature decreases, the grain size of ferrite is smaller and the content of ferrite is higher, and the martensite is diffuse and uniformly distributed. Comparing with the mechanical properties shows that the yield strength of DP580 steel varies obviously with the different finishing rolling temperatures, and the larger size of ferrite results in the lower yield strength when the finishing rolling temperature is higher. Comparing with the S-N curves,it shows that the fatigue life of DP580 steel is lower when the finishing rolling temperature is higher. Thus, the ferrite with large size and the island-shaped martensite with multiple corners and irregular shape accelerate the initiation and expansion of cracks.

基金项目：

首钢科技项目（2018科1-5）

郭子峰（1984-），男，博士，高级工程师 E-mail：guozifeng5588@163.com

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