Heat Treatment V

After forging or machining:

  1. Heat to 1,650-1,750°F.
  2. Quench.
  3. Reheat to 400-1,200°F. and cool slowly.

RESTORING OVERHEATED STEEL

FIG. 65.—Chart of changes due to heating and cooling.

The effect of heat treatment on overheated steel is shown graphically in Fig. 65 to the series of illustrations on pages 137 to 144. This was prepared by Thos. Firth & Sons, Ltd., Sheffield, England.

FIG. 66.—The structure of overheated mild steel from which all the pegs were made (magnified 25 diameters). The pegs withdrawn at 720°C., or earlier, had this structure and were quite soft.