Abnormal Grain Growth Suppression in Aluminum Alloys

manufacturing
Abnormal Grain Growth Suppression in Aluminum Alloys (LAR-TOPS-225)
A post-friction stir welding heat treatment procedure that reduces abnormal grain growth and restores optimum material properties in heat treatable aluminum alloys
Overview
This innovation is a thermal processing methodology for retaining the fine-grained structure in aluminum alloys subjected to solid state welding and subsequent forming processes.

The Technology
Heat treatment of the deformed welds is desirable in order to restore the properties of the alloy negatively affected in the weld region. In these alloys, abnormal grain growth frequently occurs in friction stir welds during solution heat treatment, and is known to degrade key materials properties, such as strength, ductility and toughness. The innovation of inserting an intermediate annealing step covered here reduces abnormal grain growth during post-welding heat treatment, thereby allowing optimum mechanical properties. This is important where Al-Li alloys (and other heat treatable alloys) are friction stir welded followed by deformation processing and high performance, high reliability structural components are required for aerospace vehicles.
Friction Stir Welding Apparatus An Intermediate Annealing Step Reduces Abnormal Grain Growth. Image credit: NASA/Stephen J. Hales
Benefits
  • Enables friction stir welding to join aerospace components made from lightweight aluminum alloys, in particularl Al-Li alloys
  • Suppresses abnormal grain growth known to occur in the weld region during post-weld heat treatment
  • Simple, low-cost processing step suitable for large components or structures

Applications
  • Manufacturing structural components for aerospace vehicles, cars, trucks, trains, ships and submarines
Technology Details

manufacturing
LAR-TOPS-225
LAR-17906-1
9,090,950
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