الفهرس 
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Abstract
The present ’Nork is concerned. with the study of case •. hardening le8SS in low-caroon steel in comparison with an austenitic type of dnleas steel (304); both in solid and liquid bathes .• Carbon, nitrogen, sulfur, aluminium and chromium were used as rf~sing elements inbboth low-carbon steel and stainless steel. The ,t composition for each of th~ different case-hardening mixtures che.sen through many trials.
All the e:::periments were carried out at a. t~mperature range ~een 9GU ”(;0 1”,-0 0 C ~ D.t 25° C interval s and the time varied between ~o 9 hrs, at intervals of one hour.
The case depth of the diffusing element was measured by the ~allographic tecr~ique. By measuring the case depth, x, at each
~e, t, for each temperature, .T, the following results were obtained;
The relation between case-depth, x, and the time of diffusion, tt was found to obey Fick’s law of diffusion; = <4 Dt Where ,D, is the diffusion coefficient which is temperature depen .••
The curves for the plots of the diffused layer, x, and the time,t, were found to be similar, a fact which indicat~d that the mechan- ism of the process does not change either with time or with temp- <erature.
The relation between the diffusion coefficient, D, and the tempe¬rat~re, T,was found to obey the Arrhenius equation; > -- D e- Q/RT cm2/ sec Where, Do, is,the frequency factor, which is independent on temperature.