AISI 8620

Typical analysis

C	Mn	P	S	Si	Mo	Ni	Cr
0.18-0.23	0.7-0.9	max 0.035	max 0.040	0.15-0.35	0.15-0.25	0.4-0.7	0.4-0.7

An alloy steel designed for case hardening applications. The nickel imparts good toughness and ductility. The chromium and molybdenum contribute increased hardness penetration and wear, that may be carburized. The well balanced alloy content permits hardening to produce a hard wear resistant case combined with a core strength in the order of 125,000 PSI. It has excellent machinability and responds well to polishing applications.. With the balanced analysis, this steel provides, uniform case depth, hardness and wear properties, and gives the advantage of low distortion.

Typical applications

Caburized splined shafts, piston pins, cam shafts, guide pins, bushings, automotive differential pinions and transmissions, arbors, bearings, sleeves king pins, carburized gears, general engineering purposes.

Mechanical properties

As supplied.
The following are average values and may be considered as representative.

Tensile strength	PSI	85,500
Yield strength	PSI	52,000
Elongation	%	28
Reduction in area	%	61
Brinell hardness		186

Forging and Heat Treating Parameters

Thermal Process	Temperature (Celsius)
Forging	Commence at 1200°C Max. Finish at 950°C
Annealing	856°C - 926o°C Cool Slowly in Furnace
Normalizing	898°C - 926°C Cool in Air
Hardening and Tempering	(Uncarburized) - 815°C - 855°C Oil or Water Quench, temper at 200°C to 650°C according to strength level required. (Carburizing) - Direct Oil Quenching 1. Oil quench direct from carburizing temperature. Draw at desired temperature for at least 1 to 2 hours per inch of section. 2. Single refine - Box cool from pack carburizing or air cool from other media. Reheat to 829°C - 842°C , oil quench. Draw at desired temperature for minimum 1 to 2 hours per inch of section. (provides good case hardness and core properties) 3. Double refine - Box cool from carburizing media. Reheat to 829°C - 842V, oil quench. Reheat to 760°C - 787°C , oil quench. Draw at desired temperature for minimum 1 - 2 hours per inch of section. (Provides optimum combination of case hardness, core strength and toughness)