The metallography of iron and steel

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Page 183 - As the components of a system there are to be chosen the smallest number of independently variable constituents by means of which the composition of each phase participating in the state of equilibrium can be expressed in the form of a chemical equation...
Page 41 - Probably aggregate. (Arnold, troostitic pearlite). Definition. In the transformation of austenite, the stage following martensite and preceding sorbite (and osmondite if this stage is recognized). Constitution and composition. An uncoagulated conglomerate of the transition stages. The degree of completeness of the transformation represented by it is not definitely known and probably varies widely. Osmond and most others believe that the transformation, while generally far advanced, yet falls materially...
Page 123 - The latter possesses the advantage that the experimenter may watch any part of the record, and can therefore control the operation and at any moment vary the conditions affecting the experiment; whereas with a photographic recording apparatus, as usually constructed, the observer does not know whether or not the experiment is progressing properly until it is finished and he has developed the sensitive plate. The manipulation by the photographic method is usually also more delicate and time consuming...
Page xix - ... led to study its anatomy, ie its physical and chemical constitution; its biology, ie the influence exerted upon its constitution by the various treatments, thermal and mechanical, to which the metal is lawfully subjected; and its pathology, ie the action of impurities and defective treatments upon its normal constitution.
Page 38 - The present definition is confined to maximum rapidity of dissolving, because we do not yet know that this in all cases co-exists with the maximum depth of coloration, and in any case in which these two should not co-exist, the old definition does not decide which is true osmondite. Constitution. — The following hypotheses have been suggested, none of which has firm experimental foundation: (1) A solid solution of carbon or an iron carbide in alpha iron. (2) The colloidal system of Benedicks in...
Page xvii - That so much has been accomplished in so short a time is highly gratifying to the many workers, practical or scientific, who have contributed by their efforts to the progress of metallography. To realize the practical importance of metallography it should be borne in mind that the physical properties of metals and alloys — that is, those properties to which these substances owe their exceptional industrial importance — are much more closely related to their proximate than to their ultimate composition,...
Page 39 - In slowly cooled steels and cast iron containing 0.50 per cent of combined carbon or more, that which is generally believed to be ferrite, whether pearlitic or free, is supposed by Benedicks to be ferronite. Hardenite (Fr. Hardenite, Ger. Hardenit). Definition. — Collective name for austenite and martensite of eutectoid composition. It includes such steel (1) when above the transformation range, and (2) when hardened by rapid cooling. Observations. — On the generally accepted theory that austenite...
Page 39 - Results from the completion of the transformation of austenite brought spontaneously to the eutectoid carbon content, and hence occurs in all carbon steels and cast iron containing combined carbon and cooled slowly through the transformation range, or held at temperatures in or but slightly below that range, long enough to enable the ferrite and cementite to coagulate into a mass microscopically resoluble. Hence it is the normal constituent in Region 8. Its ferrite is stable but its cementite is...
Page 42 - Al it is clearly undersaturated. The objection to the names sorbite, troostite, martensite, and austenite, that each of them covers steel of a wide range of carbon content, is to be dismissed because a like objection applies with equal force to every generic name in existence. The theoretical matter...
Page 37 - In still less fully transformed steels (1.50 per cent carl)on steel rapidly quenched, etc.) 'it is associated with austenite; in more fully transformed ones (lower carbon steels hardened, high carbon steels oil hardened, or water hardened and slightly tempered, or hardened thick pieces even of high carbon steel) it is associated with troostite, and with some pro-eutectoid ferrite or cementite, qv, in hypo- and hyper-eutectoid steels respectively. In tempering it first changes into troostite; at 350...

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