Characterization of ultra-low carbon bainitic steels for use as weld wire consumables
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Authors
Beno, Michael L.
Subjects
Advisors
Fox, Alan G.
Date of Issue
1994-09
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The use of Ultra-Low Carbon Bainitic (ULCB) steels for weld wire applications is an area of current interest to the U. S. Navy and is being jointly studied by the Naval Postgraduate School and the Naval Surface Warfare Center, Annapolis, MD. The focus of the present work is to determine the effect of macrostructure, microstructure, and the size, distribution and chemical composition of the non-metallic inclusions on the strength and impact toughness of multipass Gas Metal Arc (GMA) and Gas Tungsten Arc (GTA) welds. Eight sample multipass GMA and GTA weldments using ULCB weld wire were studied by optical, scanning electron and transmission electron microscopy (SEM and TEM). The microstructures of the weld metals were dominantly bainitic except for the recrystallized regions of the GTA welds which had become ferritic. The macrostructure of the GMA weldments was dominated by columnar grains. SEM and optical fractography suggested that this macrostructure is responsible for the corresponding poor toughness in these weldments. In all weldments the non-metallic inclusions were found to be very small (on average % 0.5 microns) with a somewhat higher volume fraction in the GMA vice GTA weldments. Based on previous work, the small average size of these inclusions are surmised to have had very little effect on toughness
Type
Thesis
Description
Series/Report No
Department
Mechanical Engineering
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
86 p.;28 cm.
Citation
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.