Construction Techniques-O1

Composition:
   0.09 to 0.1 % carbon,
   1.1% manganese,
   0.5% chromium, and
   0.5% tungsten.

Heat treating characteristics:
   critical temperature =1475 F
   66 Rockwell C as quenched.

Advantages:
  high carbon and good resistance to decarburization
  high dimensional stability during heat treating

Source:
  normal steel suppliers