Description
AISI 8620, 1.6523 chemical composition
| 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 |
What is 8620 steel ?
8620 is a low nickel – chromium – molybdenum medium hardenability, case hardening (carburizing) steel, generally supplied in the as rolled condition with a maximum brinell hardness of 280 (Rc30).Characterised by good core strength and toughness in small to medium sections with case hardness up to Rc62 when carburized, hardened and tempered.8620 can also be used (uncarburised) as a high tensile steel, which when suitably hardened and tempered can be utilized for various applications requiring good tensile strength and reasonable toughness.Pre hardened and tempered (uncarburized) 8620 can be further surface hardened by nitriding but will not respond satisfactorily to flame or induction hardening due to its low carbon content.8620 (carburized) is used extensively by all industry sectors for light to medium stressed components and shafts requiring high surface wear resistance with reasonable core strength and impact properties.
8620 | 1.6523 case harden steel 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.
SAE 8620 Steel Specification and Relevant Standards
| Country | USA | DIN | BS | BS | Japan |
| Standard | ASTM A29 | DIN 1654 | EN 10084 | BS 970 | JIS G4103 |
| Grades | 8620 | 1.6523/ 21NiCrMo2 |
1.6523/ 20NiCrMo2-2 |
805M20 | SNCM220 |
AISI 8620 Steel Mechanical Properties
| Properties | Metric | Imperial |
| Tensile strength | 530 MPa | 76900 psi |
| Yield strength | 385 MPa | 55800 psi |
| Elastic modulus | 190-210 GPa | 27557-30458 ksi |
| Bulk modulus (typical for steel) | 140 GPa | 20300 ksi |
| Shear modulus (typical for steel) | 80 GPa | 11600 ksi |
| Poisson’s ratio | 0.27-0.30 | 0.27-0.30 |
| Izod Impact | 115 J | 84.8 ft.lb |
| Hardness, Brinell | 149 | 149 |
| Hardness, Knoop (converted from Brinell hardness) | 169 | 169 |
| Hardness, Rockwell B (converted from Brinell hardness) | 80 | 80 |
| Hardness, Vickers (converted from Brinell hardness) | 155 | 155 |
| Machinability (hot rolled and cold drawn, based on 100 machinability for AISI 1212 steel) | 65 | 65 |
ASTM 8620 Steel Heat Treatment
- Annealing
AISI 8620 steel may be given a full anneal by heat to 820℃ – 850℃, and hold until temperature is uniform throughout the section and cool in furnace or air cooled.
- Tempering
Tempering of heat treated and water quenched parts of 8620 steels (not carburized) is done at 400 F to 1300 F to improve case toughness with minimal effect on its hardness. This will also reduce the possibility of grinding cracks.
- Hardening
8620 steel will be austenitized at around 840°C – 870°C, and oil or water quenched depending upon section size and intricacy. Cool in Air or Oil required.
- Normalizing
1675ºF (910ºC) and air cool. This is another method of improving machinability in 8620 material; normalizing might also be used prior to case hardening.
SAE 8620 Steel Machinability
The 8620 alloy steel is readily machined after heat treatment and/or carburizing, should be at a minimum so as not to impair the hardened case of the part. Machining may be done by conventional means prior to heat treatment – after carburizing machining is usually limited to grinding.
Welding of 8620 Materials
The alloy 8620 may be welded as rolled condition by conventional methods, usually gas or arc welding. Preheating at 400 F is beneficial and subsequent heating after welding is recommended – consult the approved weld procedure for the method used. However, welding in the case hardened or through hardened condition is not recommended
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Grades : ASTM a105, s45c , s50c, AISI4140, AISI4340, AISI4130, 5919, 6587
