Abstract

17-4 precipitation-hardenable stainless steel, a high strength alloy developed for aircraft applications, has been examined for possible use in orthodontics. The effects of solution treatment, various refrigeration treatments, and various aging treatments on standard tensile properties were measured. Comparisons were made with the tensile properties of 18-8 stainless steel and a Co-Cr alloy presently used in orthodontics.

Solution treatment was found to decrease ultimate strength by 37.8%, 0.2% yield strength by 45.9%, and (YS)/E ratio by 36.7%, while having almost no effect on elastic modulus or percentage elongation. Refrigeration treatments had statistically significant but small effects on tensile properties. Aging at 900°F for one hour caused recovery of 98.2% of the 0.2% yield strength and 87.1% of the ultimate tensile strength present before solution treatment. Aging at higher temperatures than 900°F produced progressively lower strength values and progressively increasing elongation. The highest strength, a 41% increase over the untreated condition, was obtained without solution treatment and with an aging treatment at 900°F for one hour.

17-4 PH alloy can match the range of properties of treated or untreated Co-Cr (Blue Elgiloy) if appropriate heat treatments are chosen, however no combination of treatments of 17-4 PH was found to duplicate the convenience of a ductile state easily heat-treatable to a higher strength state that is found with Blue Elgiloy. The strength of untreated 18-8 stainless steel and 17-4 PH aged at 900°F for one hour are comparable.

The cost of the constituent elements of 17-4 PH alloy should be only a fraction of the cost of those in Co-Cr alloys, but an actual manufacturing cost comparison may not reflect this saving. The cost saving would be the primary reason for considering use of 17-4 PH.

Further investigation of this material should include smaller wire sizes, shorter duration heat treatments, resistance heat treatments, and corrosion resistance tests.

LLU Discipline

Orthodontics

Department

Dentistry

School

Graduate School

First Advisor

Donald Schmitt

Second Advisor

Joseph M. Caruso

Third Advisor

Clelan G. Ehrler

Fourth Advisor

Lawrence M. McEwen

Fifth Advisor

Jack L. Tomlinson

Sixth Advisor

Roland D. Walters

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1983

Date (Title Page)

9-1983

Language

English

Library of Congress/MESH Subject Headings

Orthodontic Wires

Type

Thesis

Page Count

vii; 74

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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