510 SUMMARY OF CURRENT RESEARCHES RELATING TO 



treatment of the liquid steel, nor the mode of cooling from below the 

 temperature at which the steel became completely solid, had any 

 influence upon the quantity, form, and distribution of the sulphide 

 inclusions. The rate of cooling during solidification, however, had a 

 considerable effect upon the size and distribution of the inclusions. 

 These observations indicated that the sulphides were present in solution 

 in the liquid steel and separated from it completely during solidification. 

 The inclusions in forged or rolled steel were not affected by heating, 

 unless the temperature approached the melting point. Lung heating 

 of one specimen at 1200° C. caused each elongated sulphide inclusion to 

 break up into a string of rounded inclusions. When the heating \v;is 

 sufficient to cause incipient fusion of the steel, the form and distribution 

 of the inclusions were completely changed, and network formations 

 resembling those found in steel castings resulted. Sulphide inclusions 

 thus appear to be wholly soluble in liquid steel and wholly insoluble in 

 solid steel. 



Changes in Mild Steel caused by Annealing.* — A. Stadeler has 

 studied the influence of length of time of annealing on the growth of 

 grain in mild steel. Specimens cut from rolled plate, 15*5 mm. thick, 

 of steel containing ■ 1 p.c. carbon, were annealed for periods of 1| hours 

 to 25 days, at a mean temperature of 860° C. A plate annealing 

 furnace in which the atmosphere contained a slight excess of carbon 

 monoxide, was used. Decarburization of the outside had begun after 

 3 hours, and was complete after 15 days annealing. Grain growth was 

 observed after :\ hours annealing. In the outer layers, which had 

 undergone some cold-work, the maximum grain diameter increased from 

 0*04 mm. to 2 "5 mm. in 72 hours, while in the interior of the plate 

 there was a regular but much less rapid grain growth, a maximum 

 diameter of 1 mm. being reached in 25 days. The normal laminated 

 microstructure of the plate became more distinct on annealing, and was 

 evident until the pearlite disappeared. 



Tungsten Steels and Nickel Steels.f — In the course of a paper 

 dealing with the chemical and mechanical relations of iron, tungsten, 

 and carbon, and of iron, nickel and carbon, J. O. Arnold and A. A. Read 

 describe the structure of the alloys prepared. In the tungsten steels the 

 pearlite was sorbitic. Tungsten does not form a double carbide with 

 iron, but when sufficient tungsten is present iron carbide is replaced by 

 tungsten carbide (tungsten cementite). The presence in steel of nickel 

 in large proportion favours the separation of graphite, which appears to 

 be a product of the decomposition of the unstable carbide Ni 3 C. 



Hardness of Iron-carbon Alloys.}: — R. Vondracek criticizes 

 Andrew's suggestion that the hardness of quenched steels is due to the 

 presence of finely-divided cementite embedded in a ground-mass of 

 austenite and a-iron. The total carbon in quenched steels is practically 

 all in solution. It is probable that the ferrite in hypoeutectoid steels 



* Ferrum, xi. (1914) pp. 271-6 (27 figs.). 



t Proc. Inst. Mech. Eng., 1914, pp. 223-79 (17 figs.). 



I Int. Zeitschr. Metallographie, vi. (1914) pp. 172-82 (3 figs.). 



