Publication:
Investigation into the mechanism of acicular ferrite nucleation in steel weld metal

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Authors
Mahony, Michael F.
Subjects
Acicular Ferrite
Shielded Metal Arc Welding
C-Mn Steel Weldments
Non-Metallic Inclusions
Advisors
Fox, Alan G.
Date of Issue
1999-06
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
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
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Thesis
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Format
xi, 85 p.;28 cm.
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
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