PURPOSE: To manufacture a high tensile strength steel sheet excellent in bendability by subjecting a slab in which the content of various alloy elements and cleanliness are specified to hot rolling and thereafter successively executing hardening and normalizing at specified temps.
CONSTITUTION: A slab contg., by weight, 0.05 to 0.2O% C, 0.05 to 0.50% Si, 0.30 to 1.80% Mn, 0.05 to 1.20% Cr, 0.05 to 1.00% Mo, 0.005 to 0.10% Al, 0.005 to 0.08% V and ≤0.003% S and satisfying ≤0.003% cleanliness by JIS G0555 and the balance Fe with inevitable impurities is subjected to hot rolling. Next, this rolled stock is subjected to hardening treatment in the temp. range of the Ac3 to 980°C and is subjected to normalizing treatment in the temp. range of the Ac1 point to < the Ac3 point. In this way, the steel sheet having ≥590N/mm2 class tensile strength and excellent in bendability can be obtd.
| WO/2005/100823 | PINION SHAFT |
| JPS5811726 | BRIGHT QUENCHING METHOD |
TONE SHOJI
OKANO SHIGEO
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