Cold rolled and continuously annealed high strength steel strip and method for producing said steel
OwnerDavid Neal Hanlon, Margot Julia Vlotinventors
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Abstract
Cold rolled and continuously annealed high strength steel strip including (in wt %): 0.04-0.30% C, 1.0-3.5% Mn, 0-1.0% Si, 0-2.0% Al, 0-1.0% Cr, 0-0.02% P, 0-0.01% S, 0-0.25% V, 0-0.1% Nb, 0-0.20% Ti, 0-0.015% N, 0-0.010% B, unavoidable impurities, balance iron, provided with a hot dip galvanized or galvannealed zinc alloy coating layer, wherein the zinc alloy is 0.3-4.0% Mg and 0.05-6.0% Al; optionally at most 0.2% of one or more additional elements; unavoidable impurities; the remainder being zinc, and method for producing it.
Claims27
Cold rolled and continuously annealed high strength steel strip comprising (in wt %):
- 0.04-0.30% C
- 1.0-3.5% Mn
- 0-1.0% Si
- 0-2.0% Al
- 0-1.0% Cr
- 0-0.02% P
- 0-0.01% S
- 0-0.25% V
- 0-0.1% Nb
- 0-0.20% Ti
- 0-0.015% N
- 0-0.010% B
- unavoidable impurities
- balance iron,
- provided with a hot dip galvanized or galvannealed zinc alloy coating layer, wherein the zinc alloy consists of 0.3-4.0% Mg and 0.05-6.0% Al;
- optionally at most 0.2% of one or more additional elements;
- unavoidable impurities;
- the remainder being zinc.
Method for producing a cold rolled and continuously annealed high strength steel strip comprising the subsequent steps of:
- providing a cold-rolled steel strip comprising:
- 0.04-0.30% C
- 1.0-3.5% Mn
- 0-1.0% Si
- 0-2.0% Al
- 0-1.0% Cr
- 0-0.02% P
- 0-0.01% S
- 0-0.25% V
- 0-0.1% Nb
- 0-0.20% Ti
- 0-0.015% N
- 0-0.010% B
- unavoidable impurities
- balance iron
- heating the strip to an intercritical annealing temperature IAT
- holding the strip at the IAT for an annealing time sufficient to attain the desired ratio of ferrite to austenite
- cooling the strip to an over-aging temperature OAT
- holding the strip at the OAT for an over-aging time
- heating the strip to a galvanising temperature GT
- coating the strip with a zinc alloy coating layer by dipping the strip into a molten bath having a zinc bath temperature ZBT containing the zinc alloy for the zinc alloy coating layer
- cooling the coated strip.
Dependencies are inferred from the claim text.