370 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



Constitution of Steel.* — W. Rosenhain gives an account of the 

 constitution of steel from the point of view of the allotropic theory. 

 Austenite, ferrite, pearlite and cementite are defined with some precision 

 and allotted their places in the equilibrium diagram. The other decom- 

 position products of austenite do not permit of precise definition. 

 Martensite probably contains y3-iron, and owes its hardness partly to 

 this and partly to the fact that it is in large part a supercooled solid 

 solution. In troostite the iron is probably still in the (i condition, but 

 the carbide of iron is in suspension, not in solution. 



Influence of Gases upon the Critical Ranges of the Iron-carbon 



Alloys. t — In the course of this investigation, J. H. Andrew has ex- 

 amined microscopically specimens of wrought iron and 0*5 p.c, carbon 

 steel which had been heated in ammonia gas at 1000° C. for forty hours. 

 Well defined Neumann lines were seen in a ground mass of polygonal 

 crystals. 



Carbon-molybdenum Steels. | — T. Swinden has included in a com- 

 prehensive investigation of eighteen steels containing 1 to 8 p.c. 

 molybdenum, 0'13 to 1*36 p.c. carbon, a study of their micro-structure 

 after five different heat-treatments. The pearlite is highly emulsified, 

 and the carbon content of the eutectoid is lowered with successive 

 increments of molybdenum. Molybdenum does not give rise to the 

 presence of any new constituent. 



Microscopic Examination of the Depression made on Steel by a 

 Conical Point.§ — F. Robin finds that an examination of the deformed 

 area surrounding the impression made by forcing a hard conical point 

 into a polished specimen is capable of yielding useful metallographical 

 results. Six types of deformation are distinguished and described. The 

 presence of interstrain in the original specimen may be detected by 

 the test. 



Influence of Cold-working*. || — P. Goerens has studied the influence 

 of cold-working and annealing on the structure and on many other 

 properties of iron and steel. The progress of distortion of ferrite 

 crystals and of pearlite grains is described and illustrated. When the 

 drawing of a wrought-iron, containing slag, had proceeded sufficiently 

 far, it was observed that the edges of the slag inclusions, originally 

 even, became broken and jagged. The non-ductile slag had broken 

 when the specimen was strained, and the iron liad flowed into the 

 spaces and cracks thus formed. The broken edge of the slag inclusions 

 persists after annealing, and may serve to indicate that a specimen has 

 undergone cold-work at some stage in its history. It was found that 



* Proc. Inst. Mech. Eug. (1911) pp. 241 -308 (89 figs.). 



t Iron and Steel Institute, Carnegie Scholarship Memoirs, iii. (1911) pp. 236- 

 48 (10 figs.). 



J Iron and Steel Institute, Carnegie Scholarship Memoirs, iii. (1911) pp. 66- 

 124 (12 figs.;. 



§ Iron and Steel Inst., Carnegie Scholarship Memoirs, iii. (1911) pp. 216-85 

 (14 figs.). 



ll Iron and Steel Institute, Carnegie Scholarship Memoirs, iii. (1911) pp. 320- 

 434 (69 figs.). 



