Shock heat treatment of aluminum alloy articles

Abstract

Processes for improving the strength of heat-treatable, age hardenable aluminum alloys, such as 6xxx, 2xxx and 7xxx aluminum alloys, are provided. The processes for improving the strength of heat-treatable, age-hardenable aluminum alloys involve a heat treatment step, termed “shock heat treatment,” which involves heat treatment at 200 to 350° C. that is conducted at a fast heating rate (for example 10 to 220° C./seconds) for a relatively short period of time (for example, for 60 seconds or less or for 5 to 30 seconds). In some examples, the shock heat treatment is accomplished by contact heating, such as heating an aluminum alloy article between complementary shaped heated dies of a press. Aluminum alloy articles, such as automotive panels, produced by the disclosed shock heat treatment are also provided.

1 . A heat-treated, shaped aluminum alloy article produced by:
 heating at least one part of a shaped aluminum alloy article having one or more parts, one or more times to a heat treatment temperature of 250 to 300° C. at a heating rate of 10 to 220° C./second; and,   maintaining the heat treatment temperature for a time period of 60 seconds or less,   wherein the at least one part of the shaped aluminum alloy article comprises an age-hardenable, heat-treatable aluminum alloy.   
     
     
         2 . The article of  claim 1 , further comprising:
 shaping an aluminum alloy sheet of an age-hardenable, heat-treatable aluminum alloy to form a shaped aluminum alloy article having one or more parts prior to heating the at least one part of the shaped aluminum alloy article.   
     
     
         3 . The article of  claim 1 , wherein the shaping comprises stamping, pressing and/or press-forming the aluminum alloy sheet. 
     
     
         4 . The article of  claim 1 , wherein the heat treatment temperature is maintained for 5 to 30 seconds. 
     
     
         5 . The article of  claim 1 , wherein the age-hardenable, heat-treatable aluminum alloy is a 2xxx, 6xxx or 7xxx series aluminum alloy. 
     
     
         6 . The article of  claim 1 , wherein the age-hardenable, heat-treatable aluminum alloy is in T4 temper prior to the heating step. 
     
     
         7 . The article of  claim 1 , wherein the age-hardenable, heat-treatable aluminum alloy is in T6 or T61 temper after the heating step. 
     
     
         8 . The article of  claim 1 , wherein yield strength of the age-hardenable, heat-treatable aluminum alloy is increased after the heating step by at least 30 to 50 MPa. 
     
     
         9 . The article of  claim 1 , wherein the heating is conductive heating. 
     
     
         10 . The article of  claim 1 , wherein the heating is by application of one or more heated dies of complementary shape. 
     
     
         11 . The article of  claim 1 , wherein the at least one part is the entire shaped aluminum alloy article. 
     
     
         12 . The article of  claim 1 , wherein the at least one part is at least two parts, and wherein the at least two parts of the shaped aluminum alloy article are heated at the same or different temperatures. 
     
     
         13 . The article of  claim 1 , further comprising a second heating step at a second heat treatment temperature for a second time period. 
     
     
         14 . The article of  claim 13 , wherein the second time period is different from the first time period. 
     
     
         15 . The article of  claim 13 , wherein the first heat treatment temperature and the second heat treatment temperature are two different temperatures. 
     
     
         16 . The article of  claim 15 , wherein the second heat treatment temperature is lower than the first heat treatment temperature. 
     
     
         17 . The article of  claim 1 , wherein the age-hardenable, heat-treatable aluminum alloy is a 2xxx, 6xxx or 7xxx series aluminum alloy. 
     
     
         18 . The article of  claim 1 , wherein the age-hardenable, heat-treatable aluminum alloy comprises Si from 0.4 to 1.5 wt %, Mg from 0.3 to 1.5 wt %, Cu from 0 to 1.5 wt %, Mn from 0 to 0.40 wt %, Cr from 0 to 0.30 wt %, and up to 0.15 wt % impurities. 
     
     
         19 . The article of  claim 1 , wherein the article is a motor vehicle panel. 
     
     
         20 . A motor vehicle body comprising the motor vehicle panel of  claim 19 .