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Stress distribution in engineering materials
512
CURRENT TOPICS.
[J. F. I.
larly applicable to ocean cables. An alternator is used for transmitting purposes; one pole is earthed, the other being connected through a signalling key, condenser, and sensitive relay to the line circuit. The apparatus is the same at each end of the line, the sensitive relay controlling a sluggish relay, which in turn controls a sounder. Thus firm Morse signals appear on the sounder. It is stated that when alternating current is used for signalling the capacity and resistance of the cable do not interfere with the speed of working, as in the case of direct-current systems. A New R e a g e n t for E t c h i n g Mild Steel.
W. ROSENHAIN and
J. L. HAUGtITON. (Iron and Steel Inst. Journ., lxxxlx, 515.)--To
obtain satisfactory results the following formula must be followed with considerable exactness: Ferric chloride 30 gm., concentrated hydrochloric acid IOO c.c., cupric chloride I gm., stannous chloride o. 5 gm., water I litre. In pure carbon steels the resulting pattern is the reverse of that produced by picric acid, but the most important property of the new reagent lies in the fact that it reveals in an unnlistakable manner the distribution of phosphorus in mild steels, yielding results which are comparable with those obtained by heattinting. The cause of the pattern is the deposition of very thin films of copper. In unhardened steels ferrite is colored black, while in hardened steels martensite is developed in a remarkably clear manner. In commercial steels patterns identical with those obtained by heat-tinting are produced. The new reagent is extremely sensitive to the presence of phosphorus, the ferrite containing the least amount of phosphorus in solution being darkened first. It is therefore much more sensitive than picric acid in revealing the presence of ghosts. It appears that the width and distribution of the phosphorus banding depend upon the size and arrangement of the crystals in the original ingot. There is always considerable darkening round the enclosures of slag and sulphides in steel, which appears to indicate that there is a concentration of dissolved impurities in the immediate vicinity of such enclosures.
Stress Distribution in Engineering Materials. (Engineering, xcviii, 315.)--The object is to collect complete and systematic data on the stress distribution in a dead, mild steel containing o.12 per cent. carbon, an axle steel containing 0.3 per cent. carbon, and a nickel steel. In a preliminary report Rogers gives an outline of the method of manufacture of the dead, mild steel, and Filon and Coker summarize the methods which have been proposed and used for the determination of the distribution of stress and strain in solids.
¢ P R E S S OP J . B. L I P P I N C O T T C O M P A N Y PHILADSrLP~IA
CURRENT TOPICS.
[J. F. I.
larly applicable to ocean cables. An alternator is used for transmitting purposes; one pole is earthed, the other being connected through a signalling key, condenser, and sensitive relay to the line circuit. The apparatus is the same at each end of the line, the sensitive relay controlling a sluggish relay, which in turn controls a sounder. Thus firm Morse signals appear on the sounder. It is stated that when alternating current is used for signalling the capacity and resistance of the cable do not interfere with the speed of working, as in the case of direct-current systems. A New R e a g e n t for E t c h i n g Mild Steel.
W. ROSENHAIN and
J. L. HAUGtITON. (Iron and Steel Inst. Journ., lxxxlx, 515.)--To
obtain satisfactory results the following formula must be followed with considerable exactness: Ferric chloride 30 gm., concentrated hydrochloric acid IOO c.c., cupric chloride I gm., stannous chloride o. 5 gm., water I litre. In pure carbon steels the resulting pattern is the reverse of that produced by picric acid, but the most important property of the new reagent lies in the fact that it reveals in an unnlistakable manner the distribution of phosphorus in mild steels, yielding results which are comparable with those obtained by heattinting. The cause of the pattern is the deposition of very thin films of copper. In unhardened steels ferrite is colored black, while in hardened steels martensite is developed in a remarkably clear manner. In commercial steels patterns identical with those obtained by heat-tinting are produced. The new reagent is extremely sensitive to the presence of phosphorus, the ferrite containing the least amount of phosphorus in solution being darkened first. It is therefore much more sensitive than picric acid in revealing the presence of ghosts. It appears that the width and distribution of the phosphorus banding depend upon the size and arrangement of the crystals in the original ingot. There is always considerable darkening round the enclosures of slag and sulphides in steel, which appears to indicate that there is a concentration of dissolved impurities in the immediate vicinity of such enclosures.
Stress Distribution in Engineering Materials. (Engineering, xcviii, 315.)--The object is to collect complete and systematic data on the stress distribution in a dead, mild steel containing o.12 per cent. carbon, an axle steel containing 0.3 per cent. carbon, and a nickel steel. In a preliminary report Rogers gives an outline of the method of manufacture of the dead, mild steel, and Filon and Coker summarize the methods which have been proposed and used for the determination of the distribution of stress and strain in solids.
¢ P R E S S OP J . B. L I P P I N C O T T C O M P A N Y PHILADSrLP~IA