Coated hot- and cold-rolled steel sheet comprising a very high resistance after thermal treatment

• US 6,296,805 B1
• Filed: 07/09/1999
• Issued: 10/02/2001
• Est. Priority Date: 07/09/1998
• Status: Expired due to Term

• Current Assignee: Arcelormittal (ArcelorMittal SA)
• Original Assignee: Sollac, Co.
• Inventors: Devroc, Jacques, Hennechart, Jean-Paul, Spehner, Dominique, Laurent, Jean-Pierre
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): SAVAGE, JASON L
• Application Number:
  US09/350,100
• Time in Patent Office: 816 Days
• Field of Search: 428/653, 428/939, 420/104, 148/537, 148/531
• US Class Current: 420/104
• CPC Class Codes: C21D 8/0278 involving a particular surface treatment C21D8/0294 takes precedence
• CPC Class Codes: C22C 38/32 with boron
• CPC Class Codes: C22C 38/38 with more than 1.5% by weight of manganese
• CPC Class Codes: Y10S 428/939 Molten or fused coating
• CPC Class Codes: Y10T 428/12757 Fe

Abstract

Hot-rolled steel sheet which then can be cold-rolled, coated, the steel in the sheet having the following composition by weight:

0.15%<carbon<0.5%

0.5%<manganese<3%

0.1%<silicon<0.5%

0.01%<chromium<1%

titanium<0.2%

aluminum<0.1%

phosphorus<0.1%

sulfur<0.05%

0.0005%<boron<0.08%, the remainder being iron and impurities inherent in processing, the sheet ensuring a very high mechanical resistance after thermal treatment and the aluminum-based coating ensuring a high resistance to corrosion.

Claims

1. A hot-rolled coated steel sheet comprising a hot-rolled steel sheet coated with an aluminum or aluminum alloy coating, wherein the steel in the sheet comprises the following composition by weight:

0.15%<

carbon<

0.5%

0.5%<

manganese<

3%

0.1%<

silicon<

0.5%

0.01%<

chromium<

1%

titanium<

0.2%

aluminum<

0.1%

phosphorus<

0.1%

sulfur<

0.05%

0.0005%<

boron<

0.08%, the remainder being iron and impurities inherent in processing, and the steel sheet has a very high mechanical resistance after thermal treatment and the aluminum or aluminum alloy coating provides a high resistance to corrosion of the steel sheet.

2. The coated steel sheet according to claim 1, wherein the composition by weight of the sheet further comprises the following:

0.20%<

carbon<

0.5%

0.8%<

manganese<

1.5%

0.1%<

silicon<

0.35%

0.01%<

chromium<

1%

titanium<

0.1%

aluminum<

0.1%

phosphorus<

0.05%

sulfur<

0.03%

0.0005%<

boron<

0.01%, the remainder being iron and impurities inherent in processing.

3. A heat treated coated steel sheet prepared by subjecting the coated steel sheet according to claim 2, to an increase in temperature at a speed in excess of 600°

C./second.

4. A process for producing a casting comprising

shaping the coated steel sheet of claim 2,

subjecting the shaped coated steel sheet to an increase in temperature at a speed in excess of 5°

C./sec.

5. The coated steel sheet according to claim 1, wherein the ratio of titanium to nitrogen in the steel sheet in weight % is in excess of 3.42.

6. A process for producing a casting comprising

shaping the coated steel sheet of claim 5,

subjecting the shaped coated steel sheet to an increase in temperature at a speed in excess of 5°

C./sec.

7. The coated steel sheet according to claim 1, wherein the aluminum or aluminum alloy coating comprises from 9% to 10% silicon by weight, from 2% to 3.5% iron by weight, the remainder being aluminum.

8. A process for producing a casting comprising

shaping the coated steel sheet of claim 7,

subjecting the shaped coated steel sheet to an increase in temperature at a speed in excess of 5°

C./sec.

9. The coated steel sheet according to claim 1, wherein the coating comprises from 2% to 4% iron by weight, the remainder being aluminum.

10. A process for producing a casting comprising

shaping the coated steel sheet of claim 9,

subjecting the shaped coated steel sheet to an increase in temperature at a speed in excess of 5°

C./sec.

11. A process for producing a casting comprising

shaping the coated steel sheet of claim 1,

subjecting the shaped coated steel sheet to an increase in temperature at a speed in excess of 5°

C./second.

12. The process according to claim 11, wherein the casting is heated to a temperature in excess of 750°

C.

13. A heat treated coated steel sheet prepared by subjecting the coated steel sheet according to claim 1 to an increase in temperature at a speed in excess of 600°

C./second.

14. A land motor vehicle comprising the heat treated coated steel of claim 13.

15. A land motor vehicle comprising the coated steel sheet of claim 1.

16. A heat treated coated steel sheet prepared by subjecting the coated steel sheet according to claim 1 to a temperature in excess of 750°

C.