Title: Stress relief of single crystal superalloy articles
Application Number: 87104592 Application Date: 1987.06.30
Publication Number: 1019989 Publication Date: 1988.08.03
Approval Pub. Date: 1991.01.16 Granted Pub. Date: 1991.01.16
International Classifi-cation: C22F1/10
Applicant(s) Name: United Technologies Corp. Address:
Inventor(s) Name: Jacqueline Burns Wahl;John Joseph Marcin;Robert Ja
Attorney & Agent: TAO ZENGWEI
Abstract:
    Stress Relief of Single Crystal Superalloy Articles A coated nickel base superalloy single crystal turbine airfoil blade (1), which is subject to gas turbine engine operation, can crack during refurbishment by a stress corrosion mechanism when exposed to certain corrosive media. The rapid thermal cycling that occurs during typical gas turbine engine operation results in high, non-uniform stresses across the airfoil, producing large localized residual strains in the article at ambient temperatures. Exposure to a corrosive environment, such as during coating removal or agressive cleaning, can produce chordwise cracks in a large number of the airfoils exposed. Such cracking is avoided by subjecting the articles to a preliminary stress relieving heat treatment which reduces the residual strains to a level below which cracking will not occur, prior to exposure to the corrosive media.
Time: 3