Cold rolled steel
View Patent ↗A steel strip is produced having a tensile strength of at least 680 MPa but is such that the total elongation to break off of the strip after annealing is in the range 9% to 12%. Cold rolling may produce a cold reduction of the strip thickness in the range 40% to 80%. The continuously cast strip may be optionally in-line hot rolled prior to coiling to produce an initial strip thickness in the range 40% to 60%.
1. A plain carbon steel strip having an ultimate tensile strength of at least 680 MPa and an elongation to break in the range 8% to 12%.
2. The plain carbon steel strip as claimed in claim 1 , having a tensile strength of at least 700 MPa.
3. The plain carbon steel strip as claimed in claim 1 , having a thickness in the range 0.2 mm to 1.0 mm.
4. The plain carbon steel strip as claimed in claim 1 , and having an elongation to break of at least 10%.
5. The plain carbon steel strip as claimed in claim 1 , wherein the plain carbon steel is a silicon/manganese killed steel having the following composition by weight:
Carbon
0.02-0.08%
Manganese
0.03-0.80%
Silicon
0.10-0.40%
Sulphur
0.005-0.05%
Aluminum
less than 0.01%.
6. A plain carbon steel strip as claimed in claim 5 , wherein the steel has a manganese content of about 0.6% and a silicon content of about 0.3% by weight.
7. The plain carbon steel strip as claimed in claim 2 , having a thickness in the range 0.2 mm to 1.0 mm.
8. A plain carbon steel strip having an ultimate tensile strength of at least 680 MPa and an elongation to break of at least 8%.
9. The plain carbon steel strip as claimed in claim 8 , having a tensile strength of at least 700 MPa.
10. The plain carbon steel strip as claimed in claim 8 , having a thickness in the range 0.2 mm to 1.0 mm.
11. The plain carbon steel strip as claimed in claim 8 , and having an elongation to break of at least 10%.
12. The plain carbon steel strip as claimed in claim 8 , wherein the plain carbon steel is a silicon/manganese killed steel having the following composition by weight:
Carbon
0.02-0.08%
Manganese
0.03-0.80%
Silicon
0.10-0.40%
Sulphur
0.005-0.05%
Aluminum
less than 0.01%.
13. The plain carbon steel strip as claimed in claim 12 , wherein the steel has a manganese content of about 0.6% and a silicon content of about 0.3% by weight.
14. The plain carbon steel strip as claimed in claim 2 , and having an elongation to break of at least 10%.
15. The plain carbon steel strip as claimed in claim 3 , and having an elongation to break of at least 10%.
16. The plain carbon steel strip as claimed in claim 2 , wherein the plain carbon steel is a silicon/manganese killed steel having the following composition by weight:
Carbon
0.02-0.08%
Manganese
0.03-0.80%
Silicon
0.10-0.40%
Sulphur
0.005-0.05%
Aluminum
less than 0.01%.
17. The plain carbon steel strip as claimed in claim 3 , wherein the plain carbon steel is a silicon/manganese killed steel having the following composition by weight:
Carbon
0.02-0.08%
Manganese
0.03-0.80%
Silicon
0.10-0.40%
Sulphur
0.005-0.05%
Aluminum
less than 0.01%.
18. The plain carbon steel strip as claimed in claim 4 , wherein the plain carbon steel is a silicon/manganese killed steel having the following composition by weight:
Carbon
0.02-0.08%
Manganese
0.03-0.80%
Silicon
0.10-0.40%
Sulphur
0.005-0.05%
Aluminum
less than 0.01%.
.