Title: Auxil-iary heat treatment for aluminium-lithum alloys
Application Number: 90109934 Application Date: 1990.12.12
Publication Number: 1062380 Publication Date: 1992.07.01
Approval Pub. Date: Granted Pub. Date: 1997.02.19
International Classifi-cation: C22F1/04
Applicant(s) Name: The Secretary of State for Defence in Her Brit Maj Address:
Inventor(s) Name: Christopher John Peel
Attorney & Agent: WANG JINGCHAO LUO CAIXI
Abstract:
     Artificially aged aluminium-lithium alloys are given an auxiliary heat treatment ar or after completion of ageing to improve short-transverse properties, particularly fracture toughness. The auxiliary heat treatment comprises heating the material steadily to a reversion temperature above the ageing temperature by at least 20 deg.C but not higher than 250 deg.C, retaining the material briefly at temperature then cooling to room temperature. Typically the treatment involves heating to a reversion temperature in the range 190-230 deg.C with a hold at this temperature of around 5 minutes. Boosted properties decay with extended exposure to temperatures of 60 deg.C and above but may be restored by reimposition of the auxiliary heat treatment.
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