Metallurgy; an introduction to the study of physical metallurgy . iquid alloy oflead and tin—^the residual solution becomes impoverished inlead (or iron), and the temperature at which further depositiontakes place thus corresponds to a point a little further downthe line of deposition. Right down to the temperature ofthe line HIJ, therefore, there will always be a residue of 7-ironsohd solution, and the amount of this residue will be greaterthe nearer the alloy under consideration lies to the point the alloy finally reaches the temperature of the line HIJ,the residual 7-iron sohd soluti
Metallurgy; an introduction to the study of physical metallurgy . iquid alloy oflead and tin—^the residual solution becomes impoverished inlead (or iron), and the temperature at which further depositiontakes place thus corresponds to a point a little further downthe line of deposition. Right down to the temperature ofthe line HIJ, therefore, there will always be a residue of 7-ironsohd solution, and the amount of this residue will be greaterthe nearer the alloy under consideration lies to the point the alloy finally reaches the temperature of the line HIJ,the residual 7-iron sohd solution undergoes transformation enmasse, and the eutectoid body known as pearlite isformed, with a large evolution of heat. The precise meaning of the portion of the constitutional 168 STUDY OP PHYSICAL METALLURGY diagram of the iron-carbon system relating to the group of alloysgenerally known as steel, which may be taken as lying tothe left of the point D in the diagram, will be best understoodby following a few typical alloys through the cooMng and heating iOOO. ^ Time Intervals. Fig. 66.—Typical Inverse-Rate Heating and Cooling Curvesof Pure Iron (BurgeBB and Crowe). processes. At the same time the micro-structure of thesealloys can be considered. We shall begin with pure iron. A typical set of heating andcooling curves of this material, reproduced from the work ofBurgess (), is shown in Fig. 66. It will be seen that there aretwo peaks on both the heating and the coohng curves. Oncooling we commence with the iron in the 7 state, and nothing THE IRON-CARBON SYSTEM 165» occurs until the point E of the diagram is reached, at or near900° C. At this point there ia a marked evolution of heat oncooling, and the heating curve shows a corresponding absorp-tion of heat on heating, but at a sHghtly higher has been shown that the exact interval between the tempera-tures at which this transformation occurs on heating and oncooUiig depends partly upon the rate of heating
Size: 1365px × 1831px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectmetals, bookyear1922
