| 摘要 |
PURPOSE:To produce extremely low yield point steel for structure high in vibration absorbing ability by incorporating low carbon steel with the grains of hexagonal boron nitride at a specified ratio. CONSTITUTION:Low carbon steel having a compsn. contg., by weight, <=0.01% C, <=0.10% Si, <=0.20% Mn, <=0.05% P, <=0.05% S, <=0.05% Al and <=0.01% sol. N or furthermore contg. 0.01 to 0.1% Ti, and the balance Fe is melted and is subjected to deoxidizing treatment with Al, and after that, a mixture of the powder of hexagonal boron nitride (h-BN) and iron powder is added to the molten steel. This cast ingot is subjected to hot rolling and normalizing treatment and is thereafter subjected to air cooling. The steel for structure in which extra fine h-BN grains having 1 to 30nm average grain size are incorporated into the structure of the steel by the amt. expressed by 0.01%<=(h-BN)<=0.25% and having extremely low yield strength and excellent vibration absorbing ability can be produced at a relatively low cost. |
