12/17/01 - HC

Recommended heat treats for stress relieving low carbon steels

Minimum Soak time at elevated temperature is 1 hr per inch thickness of material
			
Full Anneal
	heat to 100F above transition temperature (1700-1800 F) 
	Heat Soak
	Cool at a rate no faster than 100F per hour
	(expect large microstructure changes like grain growth and conversion to
	ferrite and pearlite microstructures- heating above 1800F will cause 
	very large grain growth)

Normalize
	heat to above transition temperature (1600-1700 F)
	Heat Soak
	Cool by quenching in air (remove part from oven and let cool in air)
	(expect microstructure changes)

Process annealed or Stress Relieving 
	Heat to 1050 - 1290F (higher temperature, more stress relieved)
	Heat soak (min time of 30 minutes)
	Cool (slower cool = more stress relieved)
	(no or few microstructure changes)
			
			
Effectiveness of the heat treat can be measured by recording the material
hardness before and after the heat treat.	
			
Approximate temperatures at glowing color
			
1800F - light yellowish red
1700F - Reddish yellow
1650F - very reddish yellow
1470F - Cherry red
1300F - dark red
1150F - brown red
1000F - dark brown