Metallurgy; an introduction to the study of physical metallurgy . d Ar^ points of thelower carbon steels, and the point is consequently known asAr23 or Acgs respectively. This nomenclature is not, however,consistent with the constitutional diagram. If we accept theexistence of the 13 phase in the region EFG, then the line GIrepresents a transformation—from the y to the a state direct—which is not present in either Ar^ or Ar^, while, if we deny theexistence of the /3 phase, we must also wipe out the break inthe line EGI at the point G, and in that case the point corre-sponding to the line GI sh
Metallurgy; an introduction to the study of physical metallurgy . d Ar^ points of thelower carbon steels, and the point is consequently known asAr23 or Acgs respectively. This nomenclature is not, however,consistent with the constitutional diagram. If we accept theexistence of the 13 phase in the region EFG, then the line GIrepresents a transformation—from the y to the a state direct—which is not present in either Ar^ or Ar^, while, if we deny theexistence of the /3 phase, we must also wipe out the break inthe line EGI at the point G, and in that case the point corre-sponding to the line GI should be simply Ar^. In any case,therefore, the term Ar^s is illogical, but, since it is frequentlyused, some reference to it was essential at this point. As we have already remarked that the line EG is without anyapparent influence on the micro-structure of steel quenchedabove it or below it, the absence of this fine from the portionof the diagram relating to the steel now under discussion(0-6 per cent, carbon) will not affect the range of micro- PLATE i.^C>;-^: IS^«*4|^^HI IH^ f^ M ^^ n ^m^^m 1 Pig. 69. Fig. 70.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectmetals, bookyear1922
