冷却工艺参数对600MPa级热轧双相钢组织和性能的影响

Effect of cooling processing parameters on microstructure and properties of 600 MPa grade hot-rolled dual phase steel

利用Gleeble3500热模拟试验机研究了冷却工艺对热轧双相钢显微组织的影响,利用扫描电镜和拉伸试验对实验室轧制的双相钢进行了显微组织和力学性能分析。研究结果表明：试验用钢经830℃终轧后,空冷6-10 s后快冷至卷取温度（≤200℃）,可得到室温组织为铁素体（90.7%）＋马氏体的热轧双相钢,其屈服强度为335 MPa,抗拉强度为630 MPa,加工硬化率高达0.22,伸长率达26.6%,完全满足热轧DP590钢的要求,试样的马氏体细小弥散分布,平均铁素体晶粒尺寸较小,约为6.4μm,具有良好的冲压性能。

Effect of cooling processing parameters on microstructure of hot-rolled dual phase steel was investigated by means of Gleeble 3500 thermal simulator. Microstructure and mechanical properties of the hot-rolled dual phase steel were analyzed by scanning electron microscopy（ SEM） and tensile tests,respectively. The experimental result shows that the steel sheets finally rolled at 830 ℃,then cooled to the coiling temperature（ ≤200 ℃） after holding 6-10 s in the air,the typical ferrite（ 90. 7%） and martensite structure of the hot-rolled dual phase steel can be obtained,and its yield strength and tensile strength are 355 MPa and 630 MPa,respectively. In the meantime,the work hardening rate of the steel is up to 0. 22,the total elongation reaches 26. 6%,showing good pressing performance,can completely satisfy the requirement of hot rolled DP590 steel. Martensite in the sample is fine and dispersive,and the ferrite grain is smaller with average size about 6. 4 μm.