The Effect of Friction Stir Processing on the Microstructure and Mechanical Properties of AF/C458 Aluminum Lithium Alloy

Abstract

Aluminum-lithium alloys have been under development for lightweight-high strength aerospace structures but implementation has been slowed significantly because of poor short transverse fracture toughness and brittle intergranular delamination cracking. The alloy AF/C458 (now designated AA 2099) has been designed to exhibit decreased mechanical anisotropy and improved fracture toughness while maintaining ductility and strength levels. This thesis examines the application of Friction Stir Processing (FSP) of AF/C458 as an approach to refine and homogenize the grain structure and enhance mechanical properties. FSP of peak-aged material results in refined, equiaxed grains but with reduced hardness due to the heat input of the process. The effect of post-FSP heat treatment has been established and the influence of FSP on tensile and fatigue properties has been determined.

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 2005
Accession Number
ADA439309

Entities

People

  • Tanya L. Giles

Organizations

  • Naval Postgraduate School

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies
  • Space

DTIC Thesaurus Topics

  • Air Force
  • Alkali Metals
  • Alloys
  • Electron Microscopy
  • Friction Stir Processing
  • Friction Stir Welding
  • Hardness
  • Heat Treatment
  • Lithium Alloys
  • Materials
  • Materials Engineering
  • Materials Science
  • Mechanical Properties
  • Mechanical Working
  • Mechanics
  • Microscopy
  • Tensile Strength

Fields of Study

  • Materials science

Readers

  • Materials Science and Engineering.
  • Powder metallurgy of Titanium alloys.
  • Systems Analysis and Design

Technology Areas

  • Space