| 摘要 |
PURPOSE:To obtain a surface treated steel plate provided with both of paint baking hardenability and high corrosion resistance by subjecting a low alloy steel plate of a specific compsn. to heating, cooling and skin pass rolling under limited conditions and subjecting the same to skin pass rolling after plating and baking of painting. CONSTITUTION:The ingot contg. <=0.20% C, <=2.0% Mn, <=0.10% solAl, and if necessary <=0.150% P, <=0.8% Si, and <=0.0050% B is hot-and cold-rolled to a desired thickness. The plate is heated to Ac1-900 deg.C, and is held for 5-180 sec at these temps. The heated plate is cooled down to 300-500 deg.C at 1-1,000 deg.C/sec cooling rate and is held for 5-600sec at these temps. Thereafter, the plate is quickly cooled down to a room temp. and is carried out with zinc plating or the like, and is further coated with an org. film contg. metallic zinc powder, which film is then baked. The painted plate is subjected to skin pass rolling of 0.3- 1.5%. This surface treated steel plate has excellent corrosion resistance, press workability and weldability, and has high paint baking hardenability even after baking of the film. |
