Abstract: By utilizing different process control technologies, producing economical cold rolling DP780 with different yield ratios was realized. Through analyzing the testing results of mechanical properties, microstructural morphologies of TEM and SEM, it was obtained that the initial microstructure, cold rolling reduction and continuous annealing process had important effects on the yield ratio. The results indicated that when the initial microstructure of hot rolling was F+P, with the average grain size refined to about 7.5 μm, the yield strength was increased by 50 MPa and the yield ratio was increased to 0.56 from 0.48. When the initial microstructure of hot rolling changed to F+B(mainly bainite), the yield strength reached 532 MPa and the yield ratio was increased to 0.65, it is beneficial to guarantee the hole expansion property and plasticity of DP780 steel. The hole expanding rate was reached to 86%, which is especially suitable for automobile structural and strengthen parts with the request of hole expansion and flanging. In addition, appropriately increasing the cold rolling reduction and decreasing the soaking temperature in annealing process properly were helpful to enhance the strengthening effect of the matrix structure, thus improving the yield strength.
侯晓英,刘晓美,郝亮. 不同屈强比的冷轧DP780钢工艺调控技术分析[J]. 中国冶金, 2019, 29(2): 29-33.
HOU Xiaoying,LIU Xiaomei,HAO Liang. Analysis on process control technology of cold rolling DP780 steel with different yield ratios[J]. China Metallurgy, 2019, 29(2): 29-33.
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