ANNEALING ALLOY STEEL

The term alloy steel, from the steel maker's point of view, refers largely to nickel and chromium steel or a combination of both. These steels are manufactured very largely by the open-hearth process, although chromium steels are also a crucible product. It is next to impossible to give proper directions for the proper annealing of alloy steel unless the composition is known to the operator.

Nickel steels may be annealed at lower temperatures than carbon steels, depending upon their alloy content. For instance, if a pearlitic carbon steel may be annealed at 1,450°C., the same analysis containing 2½ per cent nickel may be annealed at 1,360°C. and a 5 per cent nickel steel at 1,270°.

In order that high chromium steels may be readily machined, they must be heated at or slightly above the critical for a very long time, and cooled through the critical at an extremely slow rate. For a steel containing 0.9 to 1.1 per cent carbon, under 0.50 per cent manganese, and about 1.0 per cent chromium, Bullens recommends the following anneal:

Heat to 1,700 or 1,750°F. Air cool to about 800°F. Soak at 1,425 to 1,450°F. Cool slowly in furnace.
  1. Heat to 1,700 or 1,750°F.
  2. Air cool to about 800°F.
  3. Soak at 1,425 to 1,450°F.
  4. Cool slowly in furnace.