SPONTANEOUS GENERATION OF HEAT IN RECENTLY 

 HARDENED STEEL. III. 



By CHARLES F. BRUSH. 

 {Read April 13, 1917.) 



The present paper is the third of a series under this title. In the 

 first paper^ it was shown that a specimen of carbon tool steel, and 

 also a specimen of " high-speed " tungsten-chromium steel after 

 hardening by water quenching at a high temperature, spontaneously 

 generated heat in appreciable quantity for at least several weeks, 

 the rate of generation steadily diminishing. It was also shown that 

 the carbon steel, after hardening, shrank progressively when tem- 

 pered to " straw " color, to " light blue " and finally annealed. It was 

 further shown that another specimen of high-carbon steel, after 

 hardening, spontaneously shrank in measurable amount for many 

 days, the rate of shrinking steadily diminishing. The plotted curve 

 of spontaneous shrinkage was strikingly similar to a curve (not 

 plotted) of total heat spontaneously generated in the other speci- 

 men of carbon steel, showing an apparent relationship between the 

 two phenomena. But it was pointed out that spontaneous shrinking 

 could not possibly be the prime cause of the spontaneous generation 

 of heat observed because it was wholly inadequate in amount. This 

 conclusion was afterward confirmed (second paper) in the cases of 

 two specimens of nickel-chromium steel which, after quenching 

 just above the temperature of decalescence, spontaneously generated 

 heat freely but did not shrink at all. 



The second paper,- after reviewing the first, treated principally 

 of two specimens of nickel-chromium steel furnished for this investi- 

 gation by Sir Robert Hadfield. Each specimen consisted of twelve 



'^Proc. Am. Phil. Soc, Vol. LIV.. No. 217, May-July, 1915. 

 -Physical Review, N. S., Vol. IX., Xo. 3. March, 1917. Proc. Royal Soc., 

 Series A, Vol. 93, Xo. A649, April 2, 1917. Joint paper with Sir R. A. Hadfield. 



PROC. AMER. PHIL. SOC, VOL. LVI, X, JULY 3I, I9I7. 



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