Patent Number: 6,168,067

Title: High strength friction stir welding

Abstract: A method for reducing material property degradation during friction stir welding. More specifically, the method includes the steps of solution heat treating first and second structural members at a first predetermined temperature schedule. The first and second structural members are then quenched to a predetermined temperature at which the structural members are in a nonequilibrium state and have an incomplete temper. The first structural member is then positioned adjacent to the second structural member, thereby defining an interface therebetween. Thereafter, the first and second structural members are joined to form a structural assembly by friction stir welding the material along the interface prior to precipitation heat treating the structural assembly. The structural assembly is then aged, such as by precipitation heat treating, at a second predetermined temperature schedule to stabilize the material properties of the resulting structural assembly, thereby completing the temper of the material. The method requires fewer manufacturing steps than conventional techniques for friction stir weld precipitation-hardened parent materials. In addition, the method minimizes the degradation of the material properties during friction stir welding, and produces a structural assembly with improved strength, hardness, and corrosion resistance, as well as dimensional quality.

Inventors: Waldron; Douglas J. (Fountain Valley, CA), Pettit; Richard G. (Ithaca, NY)

Assignee: McDonnell Douglas Corporation

International Classification: B23K 20/12 (20060101); C22F 1/057 (20060101); B23K 020/12 (); C22F 001/04 ()

Expiration Date: 01/02/2018