Al-plated steel sheet used for hot pressing and method for manufacturing Al-plated steel sheet used for hot pressing
View Patent ↗Provided is an Al-plated steel sheet used for hot pressing that has excellent lubricity in hot state, corrosion resistance after paint coating, and spot weldability. An Al-plated steel sheet used for hot pressing includes: a steel sheet; an Al plating layer formed on one surface or both surfaces of the steel sheet; and a surface coating layer formed on the Al plating layer. The surface coating layer contains a zinc compound, and the zinc compound is deposited on the Al-plated steel sheet in an amount of equal to or greater than 0.3 g/m 2 and equal to or less than 1.5 g/m 2 as an amount of metallic zinc per one surface, and a zinc deposition amount in any continuous 1 mm 2 region is 1.5 g/m 2 or less.
1. An Al-plated steel sheet used for hot pressing, comprising:
a steel sheet;
an Al plating layer formed on one surface or both surfaces of the steel sheet; and
a surface coating layer formed on the Al plating layer,
wherein the surface coating layer contains a zinc compound, and the zinc compound is deposited on the Al-plated steel sheet in an amount of equal to or greater than 0.3 g/m 2 and equal to or less than 1.5 g/m 2 as an amount of metallic zinc per one surface, and a zinc deposition amount in any continuous 1 mm 2 region is 1.5 g/m 2 or less.
2. The Al-plated steel sheet used for hot pressing according to claim 1 ,
wherein the zinc compound in the surface coating layer is zinc oxide.
3. The Al-plated steel sheet used for hot pressing according to claim 1 ,
wherein an average length RSm of a profile element in a roughness curve of a surface of the Al-plated steel sheet used for hot pressing after the formation of the surface coating layer is 500 μm or less.
4. The Al-plated steel sheet used for hot pressing according to claim 2 ,
wherein an average length RSm of a profile element in a roughness curve of a surface of the Al-plated steel sheet used for hot pressing after the formation of the surface coating layer is 500 μm or less.
5. A method for manufacturing the Al-plated steel sheet used for hot pressing according to claim 1 ,
said method comprising the steps of:
applying an application liquid containing a zinc compound and having a contact angle of equal to or greater than 20° and equal to or less than 50° with respect to the Al-plated steel sheet onto the Al-plated steel sheet including a steel sheet and the Al plating layer formed on one surface or both surfaces of the steel sheet; and
drying the Al-plated steel sheet onto which the application liquid has been applied, at a peak metal temperature of equal to or higher than 60° C. and equal to or lower than 200° C., to form a surface coating layer containing the zinc compound on the Al plating layer.
6. The method for manufacturing the Al-plated steel sheet used for hot pressing according to claim 5 ,
wherein a surface tension of the application liquid at 25° C. is equal to or greater than 20 mN/m and equal to or less than 60 mN/m.
7. The method for manufacturing the Al-plated steel sheet used for hot pressing according to claim 5 ,
wherein a viscosity of the application liquid at 25° C. is equal to or greater than 2 mPa·s and equal to or less than 20 mPa·s.
8. The method for manufacturing the Al-plated steel sheet used for hot pressing according to claim 6 ,
wherein a viscosity of the application liquid at 25° C. is equal to or greater than 2 mPa·s and equal to or less than 20 mPa·s.
9. The method for manufacturing the Al-plated steel sheet used for hot pressing according to claim 5 ,
wherein the application liquid is applied onto the Al plating layer with a roll coater.
10. The method for manufacturing the Al-plated steel sheet used for hot pressing according to claim 5 ,
wherein the zinc compound is zinc oxide.
11. The method for manufacturing the Al-plated steel sheet used for hot pressing according to claim 5 ,
wherein an average length RSm of a profile element in a roughness curve of a surface of the manufactured Al-plated steel sheet used for hot pressing after the formation of the surface coating layer is 500 μm or less.