Investigation into the mechanism of acicular ferrite nucleation in steel weld metal
By: by Michael F. Mahony
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1999
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 85
Description: Although steel with its high strength and toughness has been used extensively in all facets of construction, the joining of steels through welding has been problematic at best. The weld itself is the weakest part in any structure. This belief has been pervasive until recently when a microstructure called acicular ferrite was discovered. Acicular ferrite forms on non-metallic inclusions found within the weldment and when significant amounts are "grown", the weldment's toughness and strength approaches that of the steel-base plate. Unfortunately, the mechanism by which high level of acicular ferrite is nucleated in steel weld metal is unknown. This thesis is ground-breaking work in understanding this process and factors that can influence acicular ferrite formation. The present work has found that titanium-rich inclusions are the strongest acicular ferrite formers available, and goes on to suggest a new, undocumented compound may form if the proper amounts of titanium and aluminum within the weld are produced. The applications are far reaching as steel is used by all services for most all equipment.
Notes: "June 1999".

Thesis advisor(s): Alan G. Fox.

Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, June 1999.

Includes bibliographical references (p. 79-83).

Approved for public release; distribution unlimited.

Also available online.

Mode of access: World Wide Web.

System requirements: Adobe Acrobat reader.

US Army (USA) author.

dk/dk cc:9116 10/22/99