ABSTRACTS 



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 this issue. 



METALLURGY. — The failure of brass. — 1. Microstructure and initial 

 stress it\ wrought brasses of the type 60 per cent copper and Ifi per 

 cent zinc. P. D. Merica and R. W. Woodward. Bureau of 

 Standards Technologic Paper No. 82. Pp. 72. 1916. 

 This paper gives an account of an investigation of the cause of 

 failure of a number of articles, particularly bolts, of wrought brass of 

 the type 60 : 40 (i.e. of such material as naval brass and manganese 

 bronze) with particular reference to the microstruccure of the material 

 and the presence in it of initial stress. In the course of this investiga- 

 tion the physical properties, microstructure, and initial stress distribu- 

 tion have been studied in some 250 materials, some of which had been 

 in service (in the Catskill Aqueduct construction, in the Filtration Plant 

 of the City of Minneapolis, in the U. S. Navy Department, and in 

 the Panama Canal construction) and some of which was new material, 

 rods having been kindly furnished by several manufacturers. It was 

 shown that the initial stresses in rods could be relieved by annealing 

 for one or two hours at low temperatures, 300°C. to 400°C, at which 

 the physical properties of the rods were not appreciably affected. 



P. D. M. 



METALLURGY.— The failure of brass.— 2. The effect of corrosion on 

 the ductility and strength of brass. Paul D. Merica. Bureau of 

 Standards Technologic Paper No. 83. Pp. 7. 1916. 

 Investigations of a homogeneous alpha brass have shown that the 

 electrolytic solution potential of this material is increased by the appli- 

 cation of a tensile stress. This measured increase amounts to approxi- 

 mately 0.1 millivolt for 10,000 lbs. per sq. in. of stress. 



On this fact can be based an explanation of the decrease of strength 

 and of ductility of brasses when corroded while under stress. Over 

 a roughened surface of a bar the tensile stress will vary in value, 



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