喷射冷却水流密度对控冷H型钢组织和性能的影响

Effects of Spray Cooling Water Flow Density on Microstructure and Properties of Controlled Cooling H Section Steel

以Q235B钢坯为试验原材料,分别设计了三种不同的喷射冷却水流密度。采用控制冷却工艺热轧制了规格为H200 mm×100 mm的H型钢。用金相显微镜和显微硬度计对H型钢金相组织和显微硬度进行了测试,使用万能试验机检测了H型钢拉伸性能。结果表明,随着水流密度增加,H型钢组织中铁素体含量减少,珠光体含量增加,晶粒明显细化,珠光体层片细小弥散。当水流密度增加到22.6 L/(m2·s)时,显微组织中还出现了少量的贝氏体强化相,H型钢显微硬度明显上升;终冷温度呈加速下降的趋势,屈服强度和抗拉强度则呈加速上升的趋势,伸长率随水流密度的增加而加速下降。

Taking Q235 B steel as the raw materials of the experiment, three different spray cooling water flow densities were designed respectively. The H200 mm×100 mm H section steels were rolled in hot state by using the controlled cooling process. The microstructure and micro-hardness of H section steels were tested by using optical microscope and micro-hardness tester. And tensile properties of H section steel were tested by using universal testing machine. The results show that with the increase of water flow density, the ferrite content decreases and the pearlite content increases in the H section steel microstructure, the grains refine obviously, and the lamellar pearlites are dispersed. When the water density increases to 22.6L/（m2·s）, a small amount of bainite strengthening phase appears in the microstructure, and the micro-hardness increases significantly; Final cooling temperature is to accelerate the downward trend, while the yield strength and tensile strength are to accelerate decrease trend, and the percentage elongation declines quickly with the increase of the density of water flow.