TASK 70-44-02-370-003
1 . General.
CAUTION:
DO NOT APPLY THIS PROCESS TO ALUMINUM OR ALUMINUM ALLOY HARDWARE OR ASSEMBLIES, UNLESS APPROVED BY GEAE ENGINEERING.
Localized heat treatment processes are to be used only when directed by repair instructions for a particular part.
2 . Equipment.
Subtask 70-44-02-370-031
A.For equipment requirements and setup procedure, refer to TASK 70-44-01-370-002, Localized Heat Treatment Equipment and Setup.
3 . Localized Heat Treatment Cycles.
Subtask 70-44-02-370-032
WARNING:
USE THERMAL GLOVES WHEN YOU MOVE OR TOUCH HOT OR COLD PARTS. HOT OR COLD PARTS CAN CAUSE INJURY.
NOTE:
Each heat treatment cycle is identified by a letter-number code, and consists of the following temperatures, rates, and times. Heat-up and cool-down rates are general guidelines and are recommended to minimize distortion.
 
Cycle
Procedure
 
LH-1
Short age cycle for Inconel 718 fabrications, and some A286 fabrications.
 

(1)
Apply power to heating elements, and heat to 600°F (316°C) at the rate of 15 to 25°F (8 to 14°C) per minute.
 

(2)
Continue heating to 1400°F (760°C) at the rate of 3 to 4°F (1.5 to 2.25°C) per minute.
 

(3)
Hold at 1400 plus or minus 25°F (760 plus or minus 14°C) for 2 hours.
 

(4)
Reduce temperature to 1150°F (621°C) at the rate of 100°F (56°C) per hour [4 to 6°F (2.25 to 3.4°C) every 3 minutes].
 

(5)
Hold at 1150 plus or minus 25°F (621 plus or minus 14°C) for 4 hours.
 

(6)
Reduce temperature to 800°F (427°C) at the rate of 3 to 4°F (1.50 to 2.25°C) per minute.
 

(7)
Turn off power, remove insulation, and let part cool to room temperature.
 
LH-2
Full age for Ren. 41 and Ren. 77 castings.
 

(1)
Apply power to heating elements, and heat to 1400°F (760°C) at the rate of 3 to 4°F (1.50 to 2.25°C) per minute.
 

(2)
Hold at 1400 plus or minus 25°F (760 plus or minus 14°C) for 16 hours.
 

(3)
Reduce temperature to 800°F (427°C) at the rate of 3 to 4°F (1.50 to 2.25°C) per minute.
 

(4)
Turn off power, remove insulation, and let part cool to room temperature.
 
LH-3
Age/stress relief for 17-4 PH fabrications.
 

(1)
Apply power to heating elements, and heat to 1150°F (621°C) at the rate of 10 to 20°F (5.5 to 11.2°C) per minute.
 

(2)
Hold at 1150 plus or minus 25°F (621 plus or minus 14°C) for 2 hours.
 

(3)
Reduce temperature to 600°F (315.5°C) at the rate of 10 to 20°F (5.5 to 11.2°C) per minute.
 

(4)
Turn off power, remove insulation, and let part cool to room temperature.
 
LH-4
Stress relief for aluminum weld repair.
 

(1)
Apply power to heating elements, and heat to 325°F (163°C).
 

(2)
Hold at 325 plus or minus 25°F (163 plus or minus 14°C) for 6 hours.
 

(3)
Turn off power, remove insulation, and let part cool to room temperature.