Transactions . Howes hypothesis should be made onhyper-eutectic steel. If such a sample were cooled in vacuo, and ifthe formation of ferrite on the surface in the present samples is notdue to decarbonization, we should have in this hyper-eutectic steelan outside layer of carbide. With regard to Professor Stansfields remark concerning the propertemperature for hardening hyper-eutectic steel and its relation to therefining of hypo-eutectic steel, we would say, as a result of our experi-ence, that an anneal above the SE line may be necessary to refine thegrain if it is very coarse, but that such
Transactions . Howes hypothesis should be made onhyper-eutectic steel. If such a sample were cooled in vacuo, and ifthe formation of ferrite on the surface in the present samples is notdue to decarbonization, we should have in this hyper-eutectic steelan outside layer of carbide. With regard to Professor Stansfields remark concerning the propertemperature for hardening hyper-eutectic steel and its relation to therefining of hypo-eutectic steel, we would say, as a result of our experi-ence, that an anneal above the SE line may be necessary to refine thegrain if it is very coarse, but that such a temperature is wrong forquenching. On holding steel just below Acl the cementite agglom-erates into spherules between the grains of what becomes globularpearlite, and hardening such material from just above Arl results ina martensite with undissolved cementite imbedded in the grains—astructure characteristic of a large class of most successful high-carbonparts. THE POSITION OF AE3 IN CARBON-IRON ALLOYS. 653. Fig. 15.— Per Cent. Carbon Steel, Quenched in Ice Water, just abovethe Temperature of Incipient Fusion. X 500. 654 THE POSITION OF AE3 IN CARBON-IRON ALLOYS.
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
