Oxide Particle Growth During Friction Stir Welding of Fine Grain MA956 Oxide Dispersion-Strengthened Steel

• Published in: Metallurgical and materials transactions. E, Materials for energy systems Vol. 4; no. 1; pp. 1 - 12
• Main Authors: Baker, Brad W., Knipling, Keith E., Brewer, Luke N.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2017; Springer Nature B.V; ASM International
• Subjects: Aluminum oxide; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coarsening; Dispersion hardening steels; Electron imaging; Energy; Friction stir welding; Heat treating; Materials Science; Metallic Materials; Microbalances; Microhardness; Nanotechnology; Ostwald ripening; Oxide dispersion strengthening; Phase transitions; Stereology; Structural Materials; Surfaces and Interfaces; Tensile tests; Thin Films; Welding parameters; X-ray scattering; Yttrium oxide; Polycrystalline Cubic Boron Nitride; Oxide Particle; Friction Stir Welding; Scanning Transmission Electron Microscopy; Stir Zone
• ISSN: 2196-2936; 2196-2944
• DOI: 10.1007/s40553-016-0101-1

Friction stir welding of an aluminum-containing oxide dispersion-strengthened steel causes significant oxide particle growth visible at both the nano- and microscales. Quantitative stereology of scanning electron images, small-angle X-ray scattering, energy-dispersive X-ray spectroscopy, and atom-probe tomography is used to quantify the degree of particle coarsening as a function of welding parameters. Results show the dispersed oxides are significantly coarsened in the stir zone due to a proposed combination of agglomeration, Ostwald ripening, and phase transformation within the Al 2 O 3 -Y 2 O 3 system. This oxide particle coarsening effectively removes all strengthening contribution of the original oxide particles, as confirmed by uniaxial tensile tests and microhardness measurements.