HEAT TREATED ALUMINUM SHEETS AND PROCESSES FOR MAKING
Described herein is a continuous heat treatment process for metals, where a strip of a metal, e.g., a heat treatable alloy, is solutionized, rapidly cooled, thermally spiked at elevated temperature, and coiled. The continuous heat treatment process does not involve or need batch aging treatment.
1 . A process for producing a heat treated aluminum alloy comprising:
casting a metal strip;
solutionizing the cast metal strip at a line speed to produce a solutionized metal strip;
air cooling the solutionized metal strip to produce a cooled metal strip;
thermally spiking the cooled metal strip at a temperature from 150° C. to 320° C. continuously at the line speed to produce a thermally spiked metal strip;
and coiling the thermally spiked metal strip to produce a coiled metal strip.
2 . The process of claim 1 , further comprising cooling the coiled metal strip.
3 . The process of claim 2 , wherein cooling the coiled metal strip comprises air cooling the thermally spiked metal strip.
4 . The process of claim 1 , wherein only natural cooling occurs of the thermally spiked metal strip occurs between thermal spiking and coiling.
5 . The process of claim 1 , wherein coiling the thermally spiked metal strip is carried out continuously at the end of a continuous line.
6 . The process of claim 2 , wherein the cooling of the coiled metal strip is at a rate of less than or equal to 10° C./hour.
7 . The process of claim 1 , wherein the coiling of the thermally spiked metal strip is at a temperature of 110° C. to 160° C.
8 . The process of claim 1 , wherein the line speed is at least 10 meters/min.
9 . The process of claim 1 , wherein the line speed is from 10 meters/min to 120 meters/min.
10 . The process of claim 1 , wherein the thermal spike temperature is from 150° C. to 300° C.
11 . The process of claim 1 , further comprising homogenizing, hot rolling, and cold rolling the metal strip before solutionizing.
12 . The process of claim 1 , wherein thermally spiking the cooled metal strip is carried out in a reheater furnace with a length of at least 12 meters.
13 . The process of claim 1 , wherein the solutionizing temperature is from about 480° C. to about 590° C.
14 . The process of claim 1 , wherein air cooling the solutionized metal strip comprises cooling the solutionized metal strip to less than 50° C.
15 . A heat treated metal strip formed from the process of claim 1 .