AISI 8620 ALLOY STEEL | DIN 1.6523 | 20NICRMO2-2
AISI 8620,as case-hardening steel,compared with grades 8615 and 8617,it offers good core strength and toughness in small to medium sections with case hardness up to HRC62 when carburized, hardened and tempered.Pre hardened and tempered (uncarburized) 8620 can be further surface hardened by nitriding,but flame or induction hardening is not recommended due to its low carbon content.
AISI 8620 is generally supplied as annealed condition with hardness below 255HBW.
AISI 8620 Steel Chemical Composition
| Grade | C | Si | Mn | P | S | Cr | Ni | Mo |
| 8620 | 0.18-0.23 | 0.15-0.35 | 0.7-0.9 | ≤ 0.035 | ≤ 0.04 | 0.4-0.6 | 0.4-0.7 | 0.15-0.25 |
AISI 8620 Steel Related Specifications
| Europe | UK | China | Japan |
| 1.6523/20NiCrMo2-2 | 805M20 | 20CrNiMoA | SNCM220 |
AISI 8620 Steel Heat Treatment & Mechanical Property
- Forging:1150-1200°C ,furance cooling is recommended
- Normalizing：900°C – 925°C ,Cooling in air
- Annealing: 820°C – 850°C,Cooling in furnace
- Caburizing: 900°C – 925°C
- Core Refine:Reheat temperature to 840°C – 870°C during slow cooling after carburized,hold enough time for the steel to be heated uniformly, quench as required in water, oil or air cool.
- Case Hardening:Reheat the steel to 780°C – 820°C after core refining, hold enough time for the steel to be heated uniformly, and quench in oil.Followed by tempering as soon as possible.
- Tempering:150°C – 200°C,cool in still air
- Nitriding:490°C – 530°C,slow cooling
AISI 8620 Mechanical Property -Normalizing(+N) Vs Annealing(+A)
| Tensile,Mpa | Yield,Mpa | Elongation,% | Reduction,% | Charpy Impact, J | Brinell Hardness,HB | |
| +N | ≥635 | ≥355 | ≥26.3 | ≥60 | ≥100 | 183 |
| +A | ≥535 | ≥385 | ≥31.3 | ≥62 | ≥112 | 149 |
AISI 8620 Mechanical Property At Different Tempering Temperature
Section Size 25 mm, Water Quenched at 830°C
| Tempering Temperature °C | Tensile Strength Mpa | Yield Strength Mpa | Elongation % | Impact Izod J | Hardness HB |
| 205 | 1050 | 765 | 18 | 80 | 311 |
| 425 | 930 | 800 | 20 | 110 | 275 |
| 650 | 700 | 556 | 30 | 140 | 207 |
AISI 8620 Steel Quality Certification
A material test report(Inspection Certificate EN 10204 3.1) will be provided, documenting the following:
1.Chemical analysis
2.Mechanical properties
3.Surface hardness
4.Non Metallic Inclusion
5.Heat Treatment Process
6.Grain size
7.Forging ratio
8.Ultrasonic test report
AISI 8620 Steel Supply Form & Size &Surface Finish&Tolerance
| Form of Supply | Size(mm) | Length(mm) |
| Round bar | Φ6-Φ1,000 | 3,000-10,000 |
| Square bar | 100x100-600x600 | 3,000-6,000 |
| Plate/Sheet | Thickness :20-400 Width:80-1,000 | 2,000-6,000 |
| Flat bar/Blcoks | Thickness :120-800 Width:120-1,500 | 2,000-6,000 |
| Surface Finish | Black-Forged | Black-Rolled | Turned | Grinding | Polished | Peeled | Cold Drawn |
| Tolerance | (0，+5mm) | (0，+1mm) | (0，+3mm) | Best h9 | Best h11 | Best H11 | Best H11 |
Heat treatment:Quenched and Tempered (+QT), Normalizing (+N), Annealing (+A)
