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SUMMARY OF CURRENT RESEARCHES RELATING TO 
Hydrogen Decarbonization of Carbon Steels. — C. R. Austin (Iron 
and Steel Institute Meeting, May, 1922). A discussion of the influence 
of time and temperature on the rate of decarbonization by hydrogen of 
carbon steels. A very complete set of photomicrographs show how the 
temperature affects the microstructure of the partly decarbonized steels. 
The influence of time (at constant temperature) is also considered. The 
crystal structure of the carbon-free periphery is investigated, and a 
theory brought forward as a possible explanation of the “columnariza- 
tion” phenomenon. The rate of diffusion of carbon, dr iron-carbide, in 
iron is considered — based on Fick’s Law. F. I. G. R. 
Effect of Oxidizing Gases at Low Pressures on Heated Iron. — 
H. C. H. Carpenter and C. F. Elam (Iron and Steel Institute Meeting, 
May, 1922). Of chief interest to microscopists is the remarkable series 
of photomicrographs exhibited in this paper. The illustrations of 
Armco iron heated in vacuo and electrolytic iron after heating are ex- 
ceptionally interesting. Seldom has the characteristic crystalline habit 
of iron been more perfectly shown. The samples in question were heated 
from below 900° C. to above 1000° C. in an evacuated quartz tube. 
F. I. G. R. 
Delayed Crystallization in Carbon Steels — A. F. Hallimond 
(Iron and Steel Institute Meeting, May, 1922). Recent research on 
quenching has demonstrated the necessity of considering the growth of 
structures, such as martensite and troostite, which have no counterpart 
among those formed under “reversible” conditions to which the 
common theories holding in physical chemistry can be applied. In 
these irreversible cases it is essential to take account of “ delayed 
crystallization.” In considering the rate of cooling, and its influence 
upon microstructure, the following points are important : — 1. The 
existence, below the ordinary solubility curve for each constituent, of a 
range of temperature and concentration within which crystallization is 
only initiated upon the introduction of a suitable nucleus. 2. The rate 
of growth of a crystal first increases as the temperature falls below that 
of equilibrium, and then diminishes. 3. The redistribution of heat and 
dissolved matter. F. I. G. R. 
Dissolved Oxides in Steel. — E. W. Ehn (Iron and Steel Institute 
Meeting, May, 1922). The influence of oxides is explained theoretically. 
A series of photomicrographs accompany the paper. F. I. G. R. 
Formation of Globular Pearlite. — J. H. Whiteley (Iron and 
Steel Institute Meeting, May, 1922). The author shows that the carbide 
constituent of pearlite does not dissolve completely at the transformation 
Acl. Globular pearlite can be formed in hypoeutectoid steel at a tem- 
perature 15° to 20° higher than lamellar pearlite. An excellent series 
of microphotographs show instances of globular and lamellar pearlite 
existing together, and also globular pearlite starting to form. 
F. I. G. R. 
