Microstructural Development and Mechanical Properties of Friction Stir Welded Ferritic Stainless Steel AISI 409

Research output: Contribution to journalArticlepeer-review

Authors

  • M. M.Z. Ahmed
  • Mohamed M. El-Sayed Seleman
  • Mostafa Shazly
  • Moataz Attallah
  • Essam Ahmed

Colleges, School and Institutes

External organisations

  • The British University in Egypt
  • Suez University

Abstract

This work investigates the effect of friction stir welding process parameters (rotation rate and traverse speed) on the microstructural evolution of friction stir welded (FSWed) ferritic stainless steel (FSS) AISI 409. Optical microscope, scanning electron microscope and electron backscattering diffraction are used to quantitatively assess the development in grain structure and texture. The microstructural development suggested that thermo-mechanical deformation occurs in the stir zone within the austenite/ferrite phase region, ultimately transforming upon cooling into bainitic/ferritic microstructure. The fraction and size of the bainitic/ferritic grains are found to vary through the thickness of the joints. High fractions of coarse ferritic grains are found near the top of the stir zone, and low fraction of fine ferritic grains is found near the bottom of the stir zone. This bainitic/ferritic grain structure resulted in an increase in the hardness of the stir zone by about 74% relative to the base material. The tensile strength of the FSWed FSS joints is almost at the same level of the base material with reduction in the ductility as a result of the increased hardness of the weld zone.

Details

Original languageEnglish
Pages (from-to)6391-6406
Number of pages16
JournalJournal of Materials Engineering and Performance
Volume28
Issue number10
Publication statusPublished - 1 Oct 2019

Keywords

  • EBSD, ferritic stainless steel, friction stir welding, mechanical properties, microstructure