640 SUMMARY OF CURRENT RESEARCHES 



the cementite network, while the second quenching from 800° C. is 

 required to give the finely crystalline microstructure and the corre- 

 sponding " amorphous " fracture desired. 



Crystallization of Steel.* — F. Giolitti and N. Boyer find that the 

 reticulate microstructure found in hypoeutectoid steels is not due to the 

 crystallization of ferrite at the periphery of the primary mixed crystals, 

 but to the fact that the first crystals of feri'ite formed act as germs of 

 crystallization for those subsequently produced as the ferrite crystallizes 

 out on cooling. 



Coarsely Crystalline Ferrite. f — A. Stadeler describes the exces- 

 sively coarse structure of a steelworks product containing only traces of 

 carbon, with very little manganese, phosphorus, or sulphur. The 

 fracture was radiating. A section, polished and etched with copper- 

 ammonium chloride solution, showed radiating ferrite grains 5-7 mm. in 

 length. The fracture passed through the grains, not following their 

 boundaries, suggesting that the crystal junctions were stronger than the 

 ghding planes. Slag inclusions lying within a single crystal were ob- 

 served to be parallel to each other and to an edge of the crystal. It 

 was not considered probable than the specimen had undergone any long- 

 continued heating at temperatures above 650° C, but it -might have 

 been heated for considerable periods at 400-500° C. 



Influence of Manganese in Mild Steel. J — A. Stadeler has studied 

 the properties of seven series of steels containing 0'08 to 0*14 p.c. 

 carbon, the manganese in each series ranging from 0'3 to 0*7 p.c. 

 The variation in manganese content had no effect upon the micro- 

 structure. 



Formation of Temper-carbon in Malleable Cast Iron.§ — A. Lissner 

 has studied, thermally, chemically, and microscopically, the formation of 

 temper-carbon during the annealing of two series of white cast irons. In 

 one series the sulphur ranged from 0'15 to 1'24 p.c, in the other the 

 silicon ranged from 0*4 to 1*25 p.c. Microscopic examination was 

 applied to specimens which had been slowly heated to a high temperature 

 and cooled slowly, and to small pieces wdiich had been heated in a salt 

 bath at a constant temperature for a given time, and quenched in water. 

 The effect of • 05 p.c. sulphur in preventing the decomposition of iron 

 carbide is neutralized by • 28 p.c. silicon. Some of the specimens did 

 not weigh more than 1 grm. and were accordingly soldered into larger 

 pieces of steel for grinding and polishing. A 1 p.c. solution of hydro- 

 chloric acid in alcohol was used for etching. 



* Atti R. Accad. Sci. Torino, xlviii. (1913) pp. 827-35, through Jouru. Chem. 

 Soc, civ. (1913) p. 777. 



t Ferrum. x. (1913) pp. 376-9 (4 figs.). 



X Zeitschr. Anorg. Chem., Ixxxi. (1913) pp. 61-9 (6 figs.). 



§ Ferrum, x. (1912) pp. 44-54 (41 figs.). 



