. Transactions. ce many foldgreater than that of the pearlite divorce and ferrite grain-growth of our low-carbon steel. The great loss of ductility which the presence of masses ofpro-eutectoid cementite may cause is shown in Fig. 6, repre-senting the tensile properties of a steel of per cent, of car-bon, and per cent, of manganese,^^ cooled slowly from a * The matter in parentheses was not in the paper as presented, but was added onNov. 8, 1912. The microstructure of this same steel after these heat treatments is shown byoneof us in the Proceed inr/x of the American Society for l\sti
. Transactions. ce many foldgreater than that of the pearlite divorce and ferrite grain-growth of our low-carbon steel. The great loss of ductility which the presence of masses ofpro-eutectoid cementite may cause is shown in Fig. 6, repre-senting the tensile properties of a steel of per cent, of car-bon, and per cent, of manganese,^^ cooled slowly from a * The matter in parentheses was not in the paper as presented, but was added onNov. 8, 1912. The microstructure of this same steel after these heat treatments is shown byoneof us in the Proceed inr/x of the American Society for l\stin(/ Materiah,y()\. xi., p. 2(52(1911). Micrograph i>, of Kow 2, PI. II., of that paper shows tlie strong cementitenetwork in tliis steel after 6 hr. at 900°. In tlie specimen liekl for 10 min. at 900°plates of pro-eutectoid cementite can be seen under higher powers. DIVORCING ANNEALING. 537 110,000 100,000 90,000 •S 60 ^ 80,000 25 50 5 70,000 20 40 60,000 II- 15 30 - 50,000 10 20 40,000 5 10 30,000 20,000. 800 1,200 900 1,000 TEMPERATURE FROM WHICH SLOW-COOLED DEGREES CENTIGRADE. Fig. 6.—rNFLUENCE OF Heating to Various Temperatures on Hypeb-EuTECTOiD Steel of Per Cent, of Carbon when Fuknace- COOLED. Note to Fig. 6.—The |-iii. round bars as received from the maker wereheated to 625° for hr., cooled slowly in the furnace, then severally re-heated to one of the various temperatures shown, varying from 80U° to1,210°, and again, furnace-iooled. They were turned down to about in diameter before tensile testing. The specimen shown on the at 1,200° was heated at 1,200° for only 2 hr. Its elongation ismeasured in 2 in., not in 4 in. 638 DIVORCING ANNEALING. series of high temperatures, after a stay at those temperaturesof 10 min. in some cases and 6 hr. in the others. The goodductility which remained till after the maximum temperatureof heating had reached 800° fell abruptly by the time thistemperature was raised to 900°, slightly abo
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
