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 deg.C., the same analysis
containing 2-1/2 per cent nickel may be annealed at 1,360 deg.C. and
a 5 per cent nickel steel at 1,270 deg..
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:
1. Heat to 1,700 or 1,750 deg.F.
2. Air cool to about 800 deg.F.
3. Soak at 1,425 to 1,450 deg.F.
4. Cool slowly in furnace.
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