Abstract
LONDON. Institute of Metals (Autumn Meeting, Glasgow), September 3.—Robert J. Anderson and Everett G. Fahlman: The effect of low-temperature heating on the release of internal stress in brass tubes. The work was carried out to determine a suitable heat-treatment which would prevent warping of manufactures made of lead-brass tubing on standing for a period at the ordinary temperature, and at the same time effect stress release without material loss in hardness and strength. Heating for 2 or 3 hours at 325° C. or for 4 hours at 300° C. in the case of material reduced 22.4 per cent, in area is satisfactory, but the mill control of separate lots of tubing must be substantially identical if a given heat-treatment procedure is to be applied to the material.—L. H. Callendar: Passification and scale resistance in relation to the corrosion of aluminium alloys. Aluminium is a passive metal; its normal reactions are modified by the presence of a hydroxide scale of high mechanical, chemical, and electrical resistance. Corrosion in water may be started by solution or peptisa-tion of this scale; it may be stopped by precipitation of scale on the metal surface. Chlorides reduce the resistance and adherence of these scales, and carbonates tend to increase scale resistance. Nitrates passify the metal by direct oxidation and anodic polarisation. Dichromates combine the passifying action of nitrates with the formation of a highly resistant scale containing chromate.—O. W. Ellis: The influence of pouring temperature and mould temperature on the properties of a lead-base antifriction alloy. Within the limits of the experiments, the replacement of lead by antimony increases the resistance to compression and increases the hardness. The replacement of tin by copper increases the resistance to compression but scarcely affects the hardness. Mould temperatures are more important than pouring temperatures. There is evidence of an intermetallic reaction in the copper-bearing alloy in the liquid state at 334° C.—R. H. Greaves and J. A. Jones: The effect of temperature on the behaviour of metals and alloys in the notched-bar impact test. Copper, aluminium, and lead showed a continuous fall in impact figure from -80° C. to the melting-point. Maxima in the impact figure-temperature curves were shown by tin at o°, zinc at 1500, duralumin at 400°, lead-free 70: 30 brass at 800°, 60: 40 brass at 715°, 10 per cent, aluminium bronze at about 750° C. On the other hand, 70: 30 brass containing 0.02 per cent, or more of lead, and coinage bronze, showed no similar improvement in impact figure at high temperatures. A high notched-bar impact figure seems to indicate good rolling properties; for many alloys there is a range of temperature within which their behaviour on rolling is likely to be worse than at either higher or lower temperatures.—D. Hanson and Marie L. V. Gayler: On the constitution of alloys of aluminium, copper, and zinc.—Harry Hyman: The properties of some aluminium alloys. Aluminium alloys available for sand castings for engineering purposes generally possess low ductility, and this renders them difficult to manipulate in workshop practice; also they are readily susceptible to corrosion. A series of alloys was prepared with the view of passing a minimum test of 5 tons yield point, 10 tons breaking stress, and 5 per cent, elongation on sand-cast test-bars, and at the same time capable of undergoing a severe salt spray corrosion test without marked loss in weight. The alloy B.S.7, containing copper, nickel, iron, and magnesium, gave the most promising results, and has been adopted on a commercial scale.—Douglas H. Ingall: The high temperature - tensile curve: (a) Effect of rate of heating; (b) Tensile curves of some brasses. For any given load the breaking temperature and the critical inflection temperature are lower the slower the rate of heating. In the lower temperature, straight-line portion of the curve, the relationship between breaking temperature and rate of heating may follow a hyperbolic curve, which would establish a definite fundamental tensile strength for any given temperature. Alloying increases the number of loops in the higher temperature curve over a given range of temperature; this is probably due to space lattice distortion. The high temperature-tensile curves of the brasses indicate that the solution of zinc in copper1, over the α-range of composition, is not simple.—George B. Phillips: The primitive copper industry of America. There was a pre-historic copper industry in America, carried on by aborigines, who made widespread use of copper for tools, weapons, implements, ornaments, and ceremonial objects. This extensive manufacture of copper implements of similar shape to take the place of the stone and bone articles formerly used seems to justify the claim of a primitive copper culture for the American Indians, suddenly interrupted by the arrival of the Spaniards.—D. Stockdale: The α-phase boundary in the copper - tin system. Specimens were brought into equilibrium by quenching from a high temperature followed by long heat treatments at the supposed temperatures of the transformations. At ordinary temperatures the solubility of tin in copper is much higher than any previous diagram indicates; it is 16.0 per cent, of tin by weight. This result does not affect bronze-bearing metals, because such material when originally cast consists of the α and δ phases, and the hard δ shows no tendency to dissolve in the soft α at low temperatures. The existence of a transformation in the β phase has been confirmed.
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Societies and Academies. Nature 116, 415–416 (1925). https://doi.org/10.1038/116415b0
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DOI: https://doi.org/10.1038/116415b0