特高压输电铁塔用耐低温高强度角钢的研发

Development and application of angle steel with resistance to low temperature and high strength for UHV transmission tower

针对北方地区特高压电力铁塔用耐低温高强度角钢缺少问题,通过改进孔型设计和控制冷却工艺,杜绝了角钢腿部顶端和内表面出现的裂纹,减少了隐性折叠的产生,细化了角钢的晶粒尺寸,开发出Q420D角钢。技术要求满足-20℃低温冲击试验,但不满足-40℃低温冲击试验,比同规格Q345提高承载率19%～22%。给出了连铸坯化学成分的设计、孔型系统的选择和主要轧制工艺参数的制订。优化后轧制温度制度为:开轧温度950～990℃,终轧温度870～910℃,矫直温度≤100℃。

Due to the lack of angle steel with resistance to low temperature and high strength for UHV transmission tower in northern area,through the improved pass design and control cooling process,the cracks on top of leg and interior and hidden folding are completely removed,and the Q420D angle steel is developed.It satisfies-20 ℃ low temperature impulse test,however it not satisfies-20 ℃ test,the bearing rate is increased by 19%~22% than Q345.the design of continuous casting chemical composition,the selection of pass system and main rolling process parameters are given.The rolling temperature rule after optimization is： the initial rolling temperature is 950~990 ℃,the finishing temperature is 870~910 ℃,and the straightening temperature is ≤100 ℃.