| 摘要 |
PURPOSE: A process for manufacturing a bumper back beam with superior corrosion resistance and high tensile strength 80kgf/mm¬2 is provided. CONSTITUTION: The present method is characterized in that a high strength steel comprising C 0.02-0.3 wt.%, Si 0.03-0.35 wt.%, Mn 0.3-1.5 wt.%, Al 0.010-0.02 wt.%, P 0.03 wt.% or less, S 0.035 wt.% or less, and a balance of Fe is softened in the temperature range of 550 to 590°C wherein the high strength steel has tensile strength of higher than 60kgf/mm¬2.
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