锻压技术

980 MPa双相钢屈服强度偏高原因分析与改善

英文标题：Cause analysis and improvement of higher yield strength for 980 MPa dual-phase steel

单位：1.首钢京唐钢铁联合有限公司制造部 2.首钢技术研究院 3.上海汽车集团股份有限公司乘用车公司

分类号：TG142.1+2

出版年,卷(期):页码：2024,49(11):226-231

摘要：

为解决某热镀锌产线生产980 MPa双相钢出现的屈服强度异常偏高的问题，采用光谱分析仪、扫描电镜、拉伸试验机等手段研究了不同加热速率对组织性能的影响。结果表明，Nb和Ti的添加间接改变相变组织强化方式，屈服强度偏高的钢卷中Nb+Ti含量比正常钢卷高0.01%，加热速率也比正常钢卷高0.5 ℃·s-1，加热速率的提升引起钢板奥氏体化程度提升，在冷却过程中形成更多的马氏体组织，其基体中马氏体组织比例较正常钢卷提升约5%，使屈服强度提升约100 MPa。通过控制钢卷中Nb+Ti的添加含量，同时对加热速率进行限制，加热速率由2.0 ℃·s-1降低至1.5 ℃·s-1，基体中马氏体组织比例由24%左右降低至19%，使得后续大量980 MPa双相钢卷的屈服强度均达到700~850 MPa期望范围。

To solve the problem of abnormally high yield strength in 980 MPa dual-phase steel produced by a hot-dip galvanizing production line, the influences of different heating rates on the microstructure and properties were studied by spectral analyzer, scanning electron microscope, tensile testing machine and other methods. The results show that the addition of Nb and Ti indirectly changes the strengthening mode of the phase transformation structure. Nb+Ti content in the steel coil with higher yield strength is 0.01% higher than that of normal steel coil, and the heating rate is also 0.5 ℃·s-1 higher than that of normal steel coil. The increasing of heating rate leads to an increase in the degree of austenitization in the steel plate, and more martensitic structure is formed during the cooling process. The proportion of martensitic structure in the matrix is increased by about 5% compared to normal steel coil, resulting in an increasing of about 100 MPa in yield strength. By controlling the content of Nb+Ti added to the steel coil and limiting the heating rate, the heating rate is reduced from 2.0 ℃·s-1 to 1.5 ℃·s-1, and the proportion of martensitic structure in the matrix is reduced from around 24% to 19%. As a result, the yield strength for a large number of 980 MPa dual-phase steel coils reaches the expected range of 700-850 MPa.

基金项目：

作者简介：李润昌（1991-），男，硕士，副高级工程师 E-mail：lirunchang12138@163.com 通信作者：张环宇（1987-），男，学士，工程师 E-mail：15832551840@163.com

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