Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURERS MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS INFORMATION SUCH AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

Procedure

1. SUBTASK 70-37-28-370-001 Stress-relieve Martensitic Corrosion Resistant Steels

   1. Austenitizing.

      1. Increase the temperature of the part to 1775 to 1825 deg F (968 to 996 deg C) and hold for not less than one hour. CoMat 03-010 ARGON GAS standard purity, CoMat 03-120 HELIUM GAS, CoMat 03-138 HYDROGEN GAS (PROTECTIVE ATMOSPHERE), argon or helium + hydrogen, vacuum, vacuum + fast cool, vacuum + hydrogen + argon or helium, exothermic or endothermic is an acceptable atmosphere. Semi-machined parts can be austenitized in air when subsequent machining will remove at least 0.010 inch (0.254mm) from previously machined surfaces. The rate at which the temperature is increased is optional.

      2. Decrease the temperature of the part to below 300 deg F (149 deg C). The rate at which the part decreases in temperature between 1650 deg F (899 deg C) and 1000 deg F (538 deg C) is to be 35 deg F (19 deg C)/minute or faster with 50 deg F (28 deg C)/minute or faster recommended. Any convenient rate can be used below 1000 deg F (538 deg C). Subsequent tempering should be done as soon as possible.

   2. 
      CAUTION
      BE CAREFUL WITH AUSTENIZED PARTS. AUSTENIZED PARTS ARE BRITTLE AND BREAK EASILY.
      
      CAUTION
      KEEP THE PARTS CLEAN AND DRY UNTIL AFTER TEMPERING TO PREVENT CRACKING. IT IS RECOMMENDED THAT YOU TEMPER PARTS LESS THAN 24 HOURS AFTER AUSTENITIZING (LESS THAN 12 HOURS IS BETTER).

      Tempering.

      1. Temper the part at the applicable temperature (refer to table that follows) for not less that one hour to get the necessary hardness range. Subsequent rate to decrease the temperature of the part is optional. Air is an acceptable atmosphere.

      2. It is permitted to harden and/or temper the part again when the hardness requirement is not met in the initial heat treatment.

         	ALLOY TEMPERING TEMPERATURES
         Hardness Range	AMS 5613/5504 CRES (AISI 410)	AMS 5616/5508 CRES (Greek Ascoloy)
         25 to 33 HRC	1060 to 1090 deg F (571 to 588 deg C)	1175 to 1225 deg F (635 to 663 deg C)
         30 to 38 HRC	1005 to 1035 deg F (541 to 557 deg C)	1085 to 1135 deg F (585 to 613 deg C)
         32 to 38 HRC	Not Applicable	1085 to 1135 deg F (585 to 613 deg C)
         35 HRC Minimum	450 to 600 deg F +/- 10 deg F (232 to 316 deg C +/- 5 deg C) As required by Specific Repair	Not Applicable
         35 to 40 HRC	Not Applicable	1080 to 1110 deg F (582 to 599 deg C)
         45 HRC Minimum	Not Applicable	450 to 600 deg F +/- 10 deg F (232 to 316 deg C +/- 5 deg C) As required by Specific Repair