Factors affecting the strength and toughness of ultra-low carbon steel weld metal
By: by Jonathon J. Van Slyke
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1999
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 82
Description: The factors that affect strength and toughness often ultra-low carbon steel weld samples (HSLA-80 and HSLA-100), welded using the gas metal arc welding (GMAW) process and new ultra-low carbon consumable electrodes, were studied. The analysis was confined only to the weld metal, and the base metal was not considered. Analysis methods included optical microscopy, scanning electron microscopy, and transmission electron microscopy. Energy dispersive x- ray analysis was performed in the transmission electron microscope to analyze the chemical composition of non-metallic inclusions. The microstructure was found to be primarily granular ferrite with some primary ferrite, bainite, and martensite. Very little acicular ferrite was found (< 18 %). Because of this, to get the best mechanical properties in the weld, the size and volume fraction of non-metallic inclusions needs to be minimized. This can be accomplished by minimizing the amount of oxygen while increasing the amount of titanium and aluminum in the weld metal. EDX analysis revealed that the non-metallic inclusions were multi-phase particles with two predominant phases: a TiO-MnO phase and a MnO-SiO2-Al2O3, phase. Copper-sulfide caps were also found on the surface of some inclusions. This inclusion chemistry is typical of what is found in welding HSLA steel.
Notes: "December 1999"

Thesis advisor(S): A.G. Fox.

Thesis (Degree of Mechanical Engineer) Naval Postgraduate School, December 1999.

Includes bibliographical references (p. 63-64)

Approved for public release; distribution unlimited.

Also available online.

Mode of access: World Wide Web.

System requirements: Adobe Acrobat reader.

US Navy (USN) author.

dk/dk cc:9116 05/19/00