高强韧耐候桥梁钢Q500qENH的生产工艺

利用MMS-200热模拟试验机和实验室电炉进行热模拟试验和热处理试验,通过硬度、拉伸和冲击性能检测及显微组织观察,对高强韧耐候桥梁钢Q500qENH的控轧控冷工艺和热处理工艺进行了研究。结果表明:高强韧耐候桥梁钢Q500qENH宜采用热机械轧制(TMCP)+回火的生产工艺;冷却速度10~20 ℃/s、返红温度500~550 ℃、回火温度450~500 ℃时,试验钢的高强韧性和低屈强比匹配较佳;TMCP态的组织以板条贝氏体为主,回火后组织逐渐由板条状向粒状转变,且原奥氏体晶界变得更清晰;随回火温度的升高,试验钢的拉伸曲线由拱顶型向吕德斯型变化。

Production process of high strength and toughness weather-resistant bridge steel Q500 qENH

Thermal simulation test and heat treatment test were respectively performed on MMS-200 thermo simulator and laboratory electric heat treatment furnace, then the cooling process and heat treatment process of the high strength and toughness Q500qENH weathering steel for bridge were studied by means of hardness test, tensile and impact properties testing and metallurgical structure observation. The results show that the production process for high strength and toughness Q500qENH weathering steel for bridge includes thermomechanical control process(TMCP) plus tempering. When the cooling rate is 10-20 ℃/s, the re-reddening temperature is 500-550 ℃ and the tempering temperature is 450-500 ℃, the tested steel has better match of high strength-toughness and low yield-strength ratio. The microstructure by TMCP is mainly lath bainite, and after tempering, the microstructure gradually changes from bath to granular and the original austenite grain boundary becomes clearer. Tensile curve of the tested steel changes from vault type to Ludes type with the increase of tempering temperature.