Lamellar pearlite containing wrought ball-races of 100 Cr6 are placed in heat-treatment baskets. A maximum of five baskets piled up on each other are placed on the stage of a furnace. Treatment in a gas fired bell furnace transforms all lamellar pearlite to fine grain spheroidal perlite structure. The steel containing this structure has a 177-207 HB hardness value. The heat treatment process involves: heating to 550 degreesC for 3 hrs; heating to 780 degreesC, the annealing temperature, in 20 degreesC/hour steps and then holding for 6 hours; and reducing to 680 degreesC at 7 degreesC/hour. Finally the load is cooled further at any optional rate prior to dismantling.
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