| 摘要 |
<p>PURPOSE:To prevent the development of crack flaw in a steel slab at the time of hot-working by adding a specific content of REM according to As and Sb content after executing deoxidizing and desulfurizing treatments to molten steel containing the specific contents of Cu, As, and Sb. CONSTITUTION:The deoxidizing and the desulfurizing treatment are executed to the molten steel containing >=0.3% Cu and As, Sb and after making a low oxygen and low sulfur-containing steel having <=30ppm O and <=100ppm S, in the case of being <=0.05% the total of As and Sb content in the steel, the REM of Y, La and the other rare earth element metal component is added and contained so as to become 0.03-0.06%, and in the case of being >=0.05% the total of As and Sb, the REM is added and contained so that the value REM/(As+Sb) becomes 1.5-3.5. By this method, the hot workability of this steel slab is improved and the development of defect, such as crack flaw, on the steel material to be worked at the time of hot-working is prevented and steel scrap containing comparatively large contents of Cu, As, Sb, etc., can effectively be reused.</p> |
