138.    BAIN, E. C.  Rates of Reactions in Solid Steel.  Trans. Am. Inst. Min. and Met. Eng., vol. 100, 1932, pp. 13-46; Chem. Abs., vol. 27, 1933, p. 4509.

                  Basis for evaluating the contribution of any alloy addition toward the development of deep-hardening or air-hardening quality in steel is suggested, dependent on the effect of the addition to retard transformation in the 600°-500° range.  This is the only fundamental property involved in securing the final quality of hardening without drastic quench.  Mn, contributing greatly to this effect, is contrasted with Ni, which shows only a little regarding effect.  In a series of similar steels, differing substantially only in Mn, the range in transformation velocity is 1-1,000,000.  Graphite is the stable form in C in a 0.50 C-3.5 Ni steel free from significant amounts of other elements.  Cementite, because of its high speed of formation, forms in large proportion, even though less stable than graphite.  The relative velocities of the reaction producing carbide and that producing graphite are considered to be the cause of the presence of carbide alone in Ni steels in common use.  A stable condition of ferrite, austenite, and carbide in equilibrium exists in certain Mn steels and results after long heating at a proper temperature regardless of whether the original metal is austenite or pearlite, but it is reached much more quickly when the starting material is austenite.  Since white martensite is converted into coarse ferrite-carbide aggregate thousands of times faster than is austenite of the same composition, it is concluded that martensite cannot be an intermediate state in the austenite-pearlite reaction.  Almost all of these reactions show a velocity pattern very nearly that of simple first-order chemical reactions.  Certain reactions in steel begin at very high velocity and then slow up until it is barely possible to find any further change.  The solution of carbide in austenite at temperatures above A_cm and the coalescence of carbide during tempering are 2 such reactions.

                 BAKSHI, J. B.  See abs. 1190, 1191.

                 BALANDIN, A. A.  See abs. 2092.