. Transactions. d after treatment. Fig. 1 shows thestructure of manganese steel in the cast condition. Fig. 2 shows thestructure of the same steel heated to a temperature of 1,750°F. andquenched in water. The heat treatment was not correct, and althoughmuch of the free cementite has disappeared, some of it still remains inchunks as shown by the dark spots. Fig. 3 shows the structure of thesame steel heated to a temperature of 1,800°F. and quenched in this case the heat treatment is correct and all of the free cementitehas disappeared, leaving a purely austenitic structure. The effect
. Transactions. d after treatment. Fig. 1 shows thestructure of manganese steel in the cast condition. Fig. 2 shows thestructure of the same steel heated to a temperature of 1,750°F. andquenched in water. The heat treatment was not correct, and althoughmuch of the free cementite has disappeared, some of it still remains inchunks as shown by the dark spots. Fig. 3 shows the structure of thesame steel heated to a temperature of 1,800°F. and quenched in this case the heat treatment is correct and all of the free cementitehas disappeared, leaving a purely austenitic structure. The effect of subsequent heating and cooling in air is shown in and 5. Fig. 4 shows the structure of a manganese steel which hadreceived a proper heat treatment and was afterward heated to a WALTER S. MCKEE 439 temperature of 700°F. and allowed to cool in air. The structure isexactly similar to that shown in Fig. 3; the steel, therefore, has notbeen injured. Fip;. 5 shows the structure of the same steel heated to. \^• s r^ Fig. 1.—Structure op ManganeseSteel in Cast Condition. X 80Diameters. Fig. 2.—The Same Steel Incor-rectly Heat Treated, Some Cement-iTE Visible. a temperature of 750°F. and allowed to cool in air. A heavy separationof cementite, shown by the needle-like particles, is clearly visible. Thisproves that heating the steel to over 700°F. destroys the purely austenitic
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
