| 摘要 |
PURPOSE:To prevent softening by tempering and obtain superior workability and high tensile strength by making a steel plate contg. prescribed amts. of C, Mn, Si, Al, Cr, Nb, Ti into composite structure contg. ferrite phase and low temp. transformation phase. CONSTITUTION:A slab of steel consisting of 0.05-0.15% C, 2-3% Mn, 0.1- 0.8% Si, 0.01-0.1% Al, 0.1-1% Cr, 0.02-0.1% Nb and/or 0.04-0.2% Ti, and the balance Fe is made. This slab is pickled after hot rolling, and is annealed at temps. above the Ac1 transformation point and below the Ac3 transformation point whereby it is made into the composite structure contg. ferrite phase and low temp. transformation phase. When a hot-rolled steel plate having such composite structure is subjected to zinc hot dipping at high temp., it is not softened by tempering and provides high workability and high tensile strength. |
