| 摘要 |
PURPOSE: A manufacturing process is provided to lighten steel with peeling through high combining interstitial free steel plate and surface heat treating method and intensifying and to omit painting process by improving corrosion resistance for promoting process merging. CONSTITUTION: An interstitial free steel plate is used which is a metal maximizing acidifying effect since the structure consists of ferrite. Also, extrusion molding is excellent to enable tempering work. Acidifying process is conducted by nitrifying N carrier gas to CO and NH3 and steam-processing for cooling with oil. The acidifying process is performed for 60-180 minutes at 560-590deg.C. In reaction condition, if less than 560deg.C of reaction temperature, ammonium composition and nitric atom dispersion become slower for inhibiting nitrification. Activated nitric gas becomes saturation in case of over 590deg.C and Fe2N compound of high brittleness is created. In case of less than 60 min of reaction, nitric atom dispersion amount is less so creation of nitric layer is not formed. Thereby, high intensity peeling steel bumper is excellent in pressurizing molding property and precise tempering work with 30% lightened steel and 80-100% enhanced raw cost saving effect.
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