| 摘要 |
PURPOSE: A cold rolled strip capable of obtaining high strength from the final product by heat treatment (or cooling) after processing as it being processed into a complicated shaped product using low strength and high forming property before heat treatment, and a manufacturing method of the cold rolled strip are provided. CONSTITUTION: The cold rolled strip with superior heat treatment characteristics for automobile reinforcements comprises 0.20 to 0.30 wt.% of carbon, 0.5 wt.% or less of silicon, 0.02 wt.% or less of sulfur, 0.005 wt.% or less of nitrogen, 0.02 to 0.06 wt.% of aluminum, 0.02 wt.% or less of phosphorus, 1.0 to 2.0 wt.% of manganese, 0.002 to 0.006 wt.% of boron, and a balance of Fe and other inevitable impurities, wherein atomic ratio of boron/nitrogen satisfies 1 or more. The manufacturing method of the cold rolled strip with superior heat treatment characteristics for automobile reinforcements comprises the processes of hot rolling the soaked aluminum killed steel in the finish rolling temperature range of 850 to 950 deg.C that is right above Ar3 transformation point by soaking at a temperature of 1,050 to 1,300 deg.C an aluminum killed steel comprising 0.20 to 0.30 wt.% of carbon, 0.5 wt.% or less of silicon, 0.02 wt.% or less of sulfur, 0.005 wt.% or less of nitrogen, 0.02 to 0.06 wt.% of aluminum, 0.02 wt.% or less of phosphorus, 1.0 to 2.0 wt.% of manganese, 0.002 to 0.006 wt.% of boron, and a balance of Fe and other inevitable impurities, wherein atomic ratio of boron/nitrogen satisfies 1 or more; coiling the hot rolled strip in the temperature range of 650 to 800 deg.C; and cold rolling the coiled strip to a cold reduction ratio of 30 to 80%.
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