CPC C21D 9/46 (2013.01) [B32B 15/013 (2013.01); C21D 1/20 (2013.01); C21D 1/25 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0247 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/12 (2013.01); C22C 38/26 (2013.01); C22C 38/38 (2013.01); C23C 2/02 (2013.01); C23C 2/022 (2022.08); C23C 2/06 (2013.01); C23C 2/28 (2013.01); C23C 2/29 (2022.08); C23C 2/40 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01)] | 31 Claims |
1. A cold rolled, coated, annealed and post tempered steel sheet comprising:
a steel sheet including in wt. %:
C 0.1-0.3%;
Mn 1-3%;
Si 0.5-3.5%;
Al 0.05-1.5%;
Mo+Cr being between 0-1.0%; and
a zinc or zinc alloy coating on the cold rolled steel sheet;
the cold rolled, coated, annealed and post tempered steel sheet having a hole expansion from 15 to 33.7%,
a yield strength from 700 to 969 MPa; and
a tensile strength from 1100 to 1240 Mpa;
the cold rolled, coated, annealed and post tempered steel sheet formed from a steel sheet that is cold rolled and zinc coated to define a coated cold rolled steel sheet having a hole expansion that is <15%, and a yield strength that is at least 30% less than the yield strength of the cold rolled, coated and post tempered steel sheet, the coated cold rolled steel sheet annealed to define a cold rolled, coated and annealed steel sheet, the cold rolled, coated and annealed steel sheet then post tempered at a temperature between 150-650°, thereby forming the cold rolled, coated, annealed and post tempered steel sheet.
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