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为了使控轧控冷工艺生产的高性能Q500qE桥梁钢具有较低的屈强比和良好的韧性,采用Gleeble-3800试验机模拟了试验钢不同冷速控冷工艺,研究了冷速对组织和力学性能的影响。结果表明:5~25℃/s冷却速率下形成针状铁素体、粒状贝氏体铁素体和少量弥散M-A岛构成的多相组织。随冷速增加,铁素体晶粒细化,M-A岛尺寸减小;强度和屈强比提高,冲击功先升高后降低。试验钢满足力学性能要求的控冷冷却速率范围是15~20℃/s。
In order to make the high performance Q500qE bridge steel produced by the controlled rolling and controlled cooling process have lower yield ratio and good toughness, the Gleeble-3800 testing machine was used to simulate different cold controlled cooling process of the test steel, Effect of mechanical properties. The results show that multiphase microstructure composed of acicular ferrite, granular bainitic ferrite and a small amount of dispersed M-A islands is formed at a cooling rate of 5-25 ℃ / s. With the increase of cooling rate, the grain size of ferrite decreases and the size of M-A island decreases. The strength and yield ratio increase, and the impact energy increases first and then decreases. Test steel to meet the mechanical properties of the cooling rate control cooling range is 15 ~ 20 ℃ / s.