120 t转炉流程管线钢X70的生产实践

X70管线钢(%:0.02～0.05C、0.145～0.25Si、≤0.015P、≤0.002S、1.70～1.80Mn、0.085～0.15Nb、0.2～0.3Ni、0.015～0.040Al、0.01～0.03Ti)用铁水预处理-120 t转炉-RH-LF-(200～250)mm×(900～1 800)mm连铸工艺冶炼。通过金属锰替代低碳锰铁和部分硅锰合金,减少RH处理后钢水增碳,控制LF精炼时钢水增C量≤0.01%,预处理铁水[S]≤0.002%,LF精炼渣碱度控制在1.5左右,使LF初始[C]为0.03%,初始[S]为0.001 5%,终点[C]为0.04%,终点[S]为0.000 8%,满足了使用要求。

Practice of X70 Pipe Line Steel Production by 120 t Converter Flow Sheet

The X70 pipeline steel (% ： 0. 02 - 0. 05C, 0. 145 〜0. 25Si, ≤0. 015P, Wt). 002S, 1. 70 ~ 1. 80Mn, 0. 085 ~ 0. 15Nb, 0. 2 - 0. 3Ni, 0. 015 ~ 0. 040Al, 0. 01 ~ 0. 03Ti) is produced by hot metal pretreatment - 120 t converter - RH - LF - (200 ~ 250) mm x (900 ~ 1 800) mm slab concasting process. With metal manganese to replace low- carbon ferro-manganese and partial silico-manganese to decrease carbon pickup amount in liquid after RH treatment, controlling LF liquid carbon pickup amount ≤0. 01 %, controlling pretreated hot metal [ S] ≤0. 002% and basicity of LF refining slag being about 1.5, the LF initial [ C] and [ S] are respectively 0. 03% and 0. 001 5%, and the LF end [ C] and [S] are respectively 0. 04% and 0. 000 8%, to meet the requirement of service.