1943-01-01
SPECIAL ADDITION AGENT STEELS 430161
CERTAIN ferroalloys containing boron, known as “special addition agents” possess the property of markedly increasing the hardenability of many steels when added in relatively small quantities.
These additives offer promise of conserving critical alloying elements by their ability to replace important amounts of nickel, chromium, and molybdenum.
The additive treatment of steel from a commercial viewpoint is relatively new, having started in 1938.
In general, it may be stated that, with respect to hardenability and mechanical properties, a carbon steel can be made equivalent to a low-alloy steel and a low-alloy steel equivalent to a high-alloy steel by additive treatment.
The amount of additive required varies, depending upon the type of additive, the composition of the steel, and the degree of deoxidation. Uniform melting practice is essential to good results.
In spite of the exacting requirements to be met in melting treated steels, a number of mills have demonstrated their ability to melt heat after heat with as good uniformity as untreated steels. This has been borne out by the experience of the author's company and other users with a large number of heats including a number of different compositions.
Tests data pertaining to treated steels have been collected and published in an AISI report. Another survey for additional data is being planned.
A cooperative test program involving nine heats of treated steel is now in progress and a second program is about to be inaugurated.
Buick laboratory tests described herein show the effect of varying amounts of additives and comparative properties of a number of treated and untreated steels.
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