Published: Jan 1936
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It is always well to begin such a symposium as this by defining its scope. The present prevailing opinion of the interested persons in the A.F.A. is that any material which starts out as white cast iron and is subsequently heat treated to produce graphitization is to be called pearlitic malleable if the graphitization be purposely terminated when sufficient combined carbon remains to significantly affect the properties of the product. The combined carbon usually is present as pearlite although it frequently may be present as sorbite or might be martensite or some other form of decomposition product of austenite. These facts were discussed by the various committees of the American Foundrymen's Association and the term pearlitic malleable adopted even though not precisely justified metallographically since the prevailing structures are laminated or granular pearlite and sorbite between which definable distinctions are difficult to make at least simply. It is even possible that primary cementite should be considered although the instances where its existence is intentional and also in significant amount are at present extremely rare. This definition excludes material containing significant amounts of graphite as cast for in that case the material is not initially white cast iron and also excludes all those substances, many closely allied to malleable or pearlitic malleable, which as cast are high carbon steels instead of cast iron, that is, which are solid homogeneous single phased alloys at some temperature.