Steel 8620 Stress Relieved
Heat-treated state
AISI/SAE 8620 · UNS G86200 · EN 1.6523, 21NiCrMo2 · JIS SNCM220 · GB 20CrNiMo
Pick for cold-finished bar that must stay straight and dimensionally stable through heavy machining.
Values for the Stress Relieved condition
Other 8620 tempers and conditions
8620 is listed in 10 conditions; see the grade overview at 8620.
- Normalized
- As Printed
- HR
- Annealed
- HIP
- Stress Relieved
- CD
- CR
- Q&T
- Carburized
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
austenitized ~900 °C, air cooled | Use to homogenize forgings/bar and get uniform grain size and good toughness before carburizing. | 360 | 630 | 26 | 10 HRC | 8 % IACS |
binder-jetted / L-PBF and sintered 8620 powder | Use for additively made gear-steel prototypes and small-lot parts that will subsequently be carburized or Q&T. | 380 | 640 | 6 | 11 HRC | 7 % IACS |
HRDefault Hot rolled | Standard stocked condition for bar and plate that will be machined and then carburized or Q&T. | 385 | 635 | 28 | 183 HB | — |
full/subcritical anneal, softest machining condition | Pick for maximum machinability, deep cold forming or before re-heat-treatment. | 385 | 540 | 31 | 149 HB | — |
Hot isostatic pressed | Pick when residual porosity from printing/sintering must be closed for fatigue-critical gear or shaft parts. | 430 | 720 | 18 | 14 HRC | 8 % IACS |
Stress RelievedThis page cold finished + 550–650 °C stress relief | Pick for cold-finished bar that must stay straight and dimensionally stable through heavy machining. | 500 | 660 | 18 | 12 HRC | 8 % IACS |
Cold drawn | Choose for close-tolerance, good-finish bar with higher yield strength where no further heat treatment is planned. | 550 | 690 | 15 | 205 HB | — |
Cold rolled | Sheet and strip form for stamped, then carburized parts; better surface and thickness tolerance than hot rolled. | 560 | 700 | 13 | 15 HRC | 8 % IACS |
Quenched and tempered | Choose when the whole section must carry load (shafts, arbors) rather than only a carburized surface. | 850 | 1,050 | 15 | 31 HRC | — |
gas carburized, quenched, low tempered (case 58–63 HRC) | The main reason to specify 8620: hard wear/pitting-resistant case on a tough core for gears, splines and pins. | 850 | 1,100 | 10 | 60 HRC | — |
What is 8620 Stress Relieved?
8620 Stress Relieved is 8620 heat treated to Stress Relieved — pick for cold-finished bar that must stay straight and dimensionally stable through heavy machining. 8620 Stress Relieved has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 63% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi). 8620 Stress Relieved has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). HR is the default condition FabDigit quotes; Stress Relieved is available on request or by drawing note.
Advantages
- Easy to machine — 67/100, better than 95% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
8620 Stress Relieved properties
Typical room-temperature values for 8620 Stress Relieved; 23 are specific to this condition. Other listed values are 8620 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
8620 Stress Relieved has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical14
8620 Stress Relieved has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 63% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
8620 Stress Relieved is rated for continuous service to 400°C (752 °F). It conducts heat at 46.6 W/m·K (26.9 BTU/hr·ft·°F), better than 74% of steel grades. Thermal expansion is 11.6 µm/m·K (6.44 µin/in·°F).
Electrical3
8620 Stress Relieved conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 8620 Stress Relieved takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
8620 Stress Relieved's machinability is good (67/100, better than 95% of steel grades); weldability good (60/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 8620 Stress Relieved
Is 8620 easy to machine?
Machines well at ~65 % of AISI 1212 in HR/annealed condition; finish-machine before carburizing and allow grinding stock for case distortion.
Can 8620 be welded?
Weldable with low-hydrogen consumables at 0.20 % C; preheat 150–250 °C, use matching low-alloy filler and post-weld stress relieve; never weld a carburized surface.
Can 8620 be formed, bent or molded?
Cold heading and moderate bending are fine in annealed/HR condition; hot forge 1150–1230 °C and normalize afterwards to restore grain size.
What surface finishes work on 8620?
No anodizing (ferrous); protect with black oxide, phosphate, zinc or zinc-nickel plating, or oil — post-carburizing grinding gives the final gear-tooth finish.
8620 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cheat analysis, SAE/ASTM A29 | 0.18 – 0.23 | 0.2 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 0.4 – 0.7 | 0.55 |
| Cr | 0.4 – 0.6 | 0.5 |
| Mo | 0.15 – 0.25 | 0.2 |
| P | ≤ 0.04 | — |
| Smax; 8620H/resulfurized variants differ | ≤ 0.04 | — |
| Fe | balance | — |
8620 Stress Relieved — frequently asked
What is 8620 Stress Relieved used for?
8620 Stress Relieved is typically used for gears, ring gears and camshafts. In short: best carburizing steel.
What is the yield strength of 8620 Stress Relieved?
8620 Stress Relieved has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 63% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 8620 Stress Relieved easy to machine?
Reasonably — machinability is rated good (67/100, better than 95% of steel grades). Machines well at ~65 % of AISI 1212 in HR/annealed condition; finish-machine before carburizing and allow grinding stock for case distortion.
Can 8620 Stress Relieved be welded?
Yes — weldability is rated good (60/100). Weldable with low-hydrogen consumables at 0.20 % C; preheat 150–250 °C, use matching low-alloy filler and post-weld stress relieve; never weld a carburized surface.
What surface finishes work on 8620 Stress Relieved?
No anodizing (ferrous); protect with black oxide, phosphate, zinc or zinc-nickel plating, or oil — post-carburizing grinding gives the final gear-tooth finish.
Can 8620 Stress Relieved be formed, bent or molded?
Cold heading and moderate bending are fine in annealed/HR condition; hot forge 1150–1230 °C and normalize afterwards to restore grain size.
What is the maximum service temperature of 8620 Stress Relieved?
8620 Stress Relieved is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 8620-HR and 8620-CR?
HR is the default condition — standard stocked condition for bar and plate that will be machined and then carburized or Q&T. CR: sheet and strip form for stamped, then carburized parts; better surface and thickness tolerance than hot rolled. Yield strength is 385 MPa in HR versus 560 MPa in CR.
Can FabDigit make parts in 8620 Stress Relieved?
Yes — 8620 Stress Relieved is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM International (2020)
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- GB/T 3077 (20CrNiMo) — SAC (2015)
- EN 10084 — Case hardening steels (1.6523 / 21NiCrMo2-2) — CEN (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing) — ASM International (1991)
- MatWeb / MMPDS typical property listings for AISI 8620 — MatWeb / Battelle (2023)
- Binder-jet and L-PBF low-alloy 8620 powder data sheets — ExOne / Desktop Metal (2022)
- 20CrNiMo — Mysteel / 1688 (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.