Alloy Steel AISI 8620

Alloy Steel AISI ASTM 8620

General Characteristics
Alloy steel 8620 is a case-hardening steel containing nickel, chromium and molybdenum as alloying elements. The alloy shows good strength and toughness properties, and has a higher core strength than grades 8615 and 8617.

Chemical Analysis

 C%  Mn% P% S% Si% Ni% Cr% Mo%
 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 0.15/0.25

 

Applications
This alloy may be used in the production of medium-strength parts such as forged camshafts, fasteners and gears.

Forging
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.

Heat Treatment

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: 1675ºF (910ºC) 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 1525ºF (830ºC) 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 cooling from forging or subsequent heat treatment.

Weldability: This steel may be welded by normal fusion methods, but prior to carburizing or hardening and tempering.