740 SUMMARY OF CURRENT RESEARCHES RELATING TO 



are considered, the order being that of increasing stability. The changes 

 in the equilibrium curves necessitated by the supposition that a-iron and 

 y3-iron are capable of holding carbon in solution, are dealt with. The 

 alloys of iron with silicon, phosphorus, carbon and phosphorus, and 

 nickel, are briefly considered. 



Copper Steels.* — P. Breuil gives the results of shock tests on 

 notched bars, torsion tests, and hardness measurements of copper steels. 

 In the low carbon steels the presence of copper appears to reduce the 

 capacity of resisting shock. Elastic limit in torsion and work expended 

 in rupture, are raised when the copper exceeds 2 p.c. Corrosion tests 

 were made by determining the loss of weight resulting upon immersion 

 in dilute sulphuric acid for one month. The loss was smaller with 

 increase of copper up to 2 p.c. Stead's conclusions are confirmed by the 

 author's microscopic examination of the steels. With more than 4 p.c. 

 copper, red nodules of high copper content are isolated in the ingots. 

 The structure of the steels capable of being utilised — i.e. containing less 

 than 4 p.c. copper — is remarkably fine. These steels contain more 

 granulo-sorbitic pearlite as the copper content is higher. 



Brittleness and Blisters in Thin Steel Sheets.| — E. F. Law 

 found, by microscopical examination, that brittle and blistered sheets 

 were invariably of less pure steel than tough sheets. The steels from 

 which the defective sheets had been rolled, showed marked segregation 

 and contained oxide of iron. The oxide of iron, which always appears 

 to be associated with blistered sheets, is reduced by nascent hydrogen in 

 the pickling bath, with the formation of water vapour. During 

 annealing the action is reversed, the water vapour being decomposed 

 and hydrogen liberated. The internal pressure produced by these 

 reactions is sufficient to cause the formation of blisters. Brittleness is 

 frequently due to " ghost lines " rich in sulphur and phosphorus. The 

 same plate may have a wide range of ductility. 



The Relation between Type of Fracture and Micro-structure 

 of Steel Test-pieces.:}: — C. 0. Bannister has selected typical fractures 

 from a large number of broken tensile test-pieces and compared the 

 mechanical tests, chemical analysis, and microscopic constitution. His 

 main conclusions are : (1) cup fractures are obtained with homogeneous, 

 minutely crystalline or granular steel, free from slag and manganese 

 sulphide ; (2) laminated fractures are due to slag lines (manganese 

 silicate or sulphide) or " ghost lines " ; (3) steels giving irregular 

 fractures are generally inferior in quality, made up of irregular patches 

 of pearlite and ferrite, nearly always accompanied by slag lines ; (4) 

 the size of the crystals in crystalline fractures has a distinct relationship 

 to the micro-structure of the steel. 



Progress of Metallography since 1901.§— F. Osmond and G. 

 Cartaud give a comprehensive review of recent research in metallo- 

 graphy. The first paper covers the period 1901-4, the second 1904-6. 



* Comptes Rendus, cxliii. (1906) pp. 377-80. See also this Journal, 1906, p. 516. 



t Journ. Iron and Steel Inst., lxix. (1906, 1) pp. 134-60 (7 figs.). 



t Tom. cit., pp. 161-78 (25 figs.). 



§ Internat. Assoc, for Testing Materials, Brussels Congress, 1906, 86 pp., 28 figs. 



