Super CQHT high temperature alloy-resistant aluminized steel with moderate formability

1 . A coated steel sheet, comprising:

(a) a steel strip, the steel strip including a free nitrogen concentration of greater than 40 ppm, wherein the steel strip further includes, in percent weight:

carbon: less than 0.020%,

manganese: less than 0.40%,

aluminum: less than 0.015%,

nitrogen: greater than 0.008%, and

the balance including iron and impurities; and

(b) an aluminum-based coating, the aluminum-based coating being disposed on at least one surface of the steel strip,

wherein the steel strip defines a prophylactic layer at the interface between the steel strip and the aluminum-based coating, wherein the prophylactic layer includes a concentrated portion of the free nitrogen diffused from a portion of the steel strip using heat applied to the steel strip during application of the aluminum-based coating to the at least one surface of the steel strip.

2 . The coated steel of claim 1 , the aluminum-based coating being a Type-1 aluminized coating.

3 . The coated steel of claim 1 , the aluminum-based coating being a Type-2 aluminized coating.

4 . The coated steel of claim 1 , the aluminum-based coating including silicon.

5 . The coated steel of claim 1 , the aluminum-based coating including 5 to 11% silicon by percent weight.

6 . The coated steel of claim 1 , the steel strip being configured to maintain an aluminum-to-iron ratio of 90% or more in the aluminum-based coating after formation of the prophylactic layer when the steel strip subjected to a temperature of 1050° F. for at least 100 hours while in the as-coated condition.

7 . The coated steel of claim 1 , the steel strip being configured to maintain an aluminum-to-iron ratio of 90% or more in the aluminum-based coating using the prophylactic layer when the steel strip is subjected to a temperature of 1100° F. for 60 minutes or less while in the as-coated condition.

8 . The coated steel of claim 1 , the free nitrogen concentration of the steel strip being greater than 90 ppm.

9 . A coated steel, comprising: a steel strip including, in percent weight:

carbon: less than 0.020%;

manganese: less than 0.40%;

aluminum: less than 0.015%;

nitrogen: greater than 0.008%; and

the balance including iron and impurities, and

wherein the steel strip includes a free nitrogen concentration of greater than 90 ppm,

wherein the steel strip defines a prophylactic layer adjacent to one or more surfaces of the steel strip, the prophylactic layer including a concentration of diffused free nitrogen, the diffused free nitrogen being diffused into the prophylactic layer in-line with a coating process without being subjected to a box annealing process.

10 . The coated steel of claim 9 , further comprising an aluminized coating disposed on at least one surface of the steel strip.

11 . The coated steel of claim 10 , wherein the aluminized coating is a Type-1 or Type-2 aluminized coating.