Metallurgy; an introduction to the study of physical metallurgy . ee at once that, close tothe corner, the heat con-ducted into the mould fromone of the cooling surfaceswhich forms one branch ofthe angle must retard thecooling of the adjacent sur-face and vice versd ; there-fore the isothermals mustcurve inwards towards sucha corner. It follows that themetal actually at the corner wUl, for every successive layer, bethe last to solidify. The metal at these points wiU, thereforestOl be liquid when the remainder of the corresponding layersis already soUd, and, as these already solid parts tend to
Metallurgy; an introduction to the study of physical metallurgy . ee at once that, close tothe corner, the heat con-ducted into the mould fromone of the cooling surfaceswhich forms one branch ofthe angle must retard thecooling of the adjacent sur-face and vice versd ; there-fore the isothermals mustcurve inwards towards sucha corner. It follows that themetal actually at the corner wUl, for every successive layer, bethe last to solidify. The metal at these points wiU, thereforestOl be liquid when the remainder of the corresponding layersis already soUd, and, as these already solid parts tend to contractas they cool, there is an obvious tendency to produce shrinkagecracks at these points where the metal is weakest, becausehottest. also a tendency for gases and other impuri-ties to be forced into these positions, and thus to assist the otherforces in bringing about local injury. The simple cases which have been discussed above serve assufficient examples of the principles which apply to thebehaviour of castings during solidification. If we can. Fig. 124.—Diagram of Isothermalsat a Re-entrant Angle in a Cool-ing Casting. PLATE XXVII.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectmetals, bookyear1922
