超低温LNG储罐用钢的炼钢生产实践

介绍了超低温LNG储罐用钢的炼钢生产实践。采用转炉双渣、双联低温冶炼脱磷技术实现了转炉终点磷含量≤0.002 0%;钢水扒渣与LF脱硫实现了硫含量≤0.001 0%;RH真空度≤200 Pa,循环时间30 min,使钢中氮、氢含量分别控制在0.003 0%和0.000 1%以下;采用连铸全程保护浇铸工艺、铸坯高温矫直工艺以及铸坯缓冷工艺,抑制了铸坯表面和皮下裂纹的产生。

Production Practice of Smelting Ultra-low Temperature Steel for Liquefied Natural Gas Tank

The production practice of smelting ultra-low temperature steel for liquefied natu- ral gas tank is described. The content of phosphorus in molten steel at the end point of steelmaking in converter is controlled under 0.002 0% based on the converter duplex slag technique and du- plex steelmaking technique for dephosphorization at low temperature. The content of sulphur is controlled under 0.001 0% by removing the slag from molten steel and desulfurization in LF. And the content of nitrogen and hydrogen in molten steel is controlled under 0.003 0% and 0.000 1%respectively by adjusting vacuum degree up to 200 Pa and recycling time 30 minutes. For the whole procedures of casting molten steel, technologies including the protective casting process, the straightening process for strands at high temperature and slow cooling process for strands are used so that both surface cracks and subsurface cracks of a strand are controlled.