General Characteristics of Alloy Steel AISI 8720
Alloy steel 8720 is a case-hardening low-alloy steel containing nickel, chromium and molybdenum as alloying elements.
|0.18/0.23||0.70/0.90||0.040 max||0.040 max||0.20/0.35||0.40/0.70||0.40/0.60||0.20/0.30|
This alloy may be used in the production of medium-strength parts such as forged camshafts, fasteners and gears.
This alloy is forged at a start temperature of around 2250ºF (1230ºC) and could be forged down to approximately 1700ºF(925ºC.) The alloy is air cooled after forging.
Annealing: For optimum machinabilty, an as-forged structure is normally sufficient for this grade of alloy steel. If this proves not to be the case then an iso-anneal from around 1650ºF (900ºC) to 1225ºF (660ºC) will improve machinability.
Normalizing: 1700ºF (925ºC) and air cool. This is another method of improving machinability in this grade; normalizing might also be used prior to case hardening.
Hardening: The alloy will be austenitized at around 1550ºF (840ºC) and oil or water quenched depending upon section size and intricacy.
Tempering : to desired hardness, using temperatures based on past experience, following water or oil quench.
Machinability: This grade of alloy is readily machined following suitable heat treatment.
Weldability: This steel may be welded by normal fusion methods, but prior to any heat treatment that will modify the steel’s properties.