1What AISI 8822H is
AISI 8822H is a low-carbon nickel-chromium-molybdenum alloy steel intended for carburizing. It is also written SAE 8822H and listed under UNS H88220. Carbon is added to the surface at temperature, the part is quenched, and what comes out is a hard martensitic case over a low-carbon core that stays tough under shock and bending.
What the H suffix means
The H does not describe a different alloy. It describes how the steel was ordered. Plain AISI 8822 (UNS G88220) is ordered against a chemical analysis. AISI 8822H is ordered against a Jominy end-quench hardenability band set out in SAE J1268, and its chemical limits are widened slightly so the mill has room to meet that band. The H grade therefore guarantees hardening depth, not composition alone.
On a 60 mm pinion this makes little practical difference. On a 900 mm ring gear or a 600 mm forged shaft it makes a large one, since core properties at mid-radius depend on hardenability. Drawings for large carburized forgings usually call for the H grade for this reason.
Why the molybdenum matters
AISI 8822H carries 0.30 to 0.40 % molybdenum. The 8620 family carries about 0.15 to 0.25 %. Molybdenum contributes more hardenability per unit weight than the other common alloying elements, and it also reduces susceptibility to temper embrittlement. Carbon is a little higher as well, 0.19 to 0.25 % against 0.17 to 0.23 %. The result is a stronger core in thick sections and better resistance to case crushing under heavy contact load.
Specifiers generally move up to 8822H when 8620H will not harden deeply enough for the section, and stop short of 4320H or 18CrNiMo7-6 when the extra nickel is more than the duty requires.
2Chemical composition of AISI 8822H
The range below is the H band for AISI 8822H. Every heat we forge comes with a mill certificate giving the actual ladle analysis.
| Element | Content (%) | Role in the steel |
|---|---|---|
| Carbon, C | 0.19-0.25 | Sets core strength, kept low so the core stays tough |
| Manganese, Mn | 0.70-1.05 | Hardenability and deoxidation |
| Silicon, Si | 0.15-0.35 | Deoxidation, slight strengthening |
| Nickel, Ni | 0.35-0.75 | Core toughness, particularly at low temperature |
| Chromium, Cr | 0.35-0.65 | Hardenability and case wear resistance |
| Molybdenum, Mo | 0.30-0.40 | Deep hardenability, resists temper embrittlement |
| Phosphorus, P | 0.035 max | Residual, limited for toughness |
| Sulfur, S | 0.040 max | Residual, limited for transverse properties |
| Iron, Fe | Balance |
Composition per SAE J1268 and SAE J404 H band limits. Where a drawing calls for tighter limits, such as restricted sulfur for ultrasonic clearance or a narrowed carbon range for a specific case depth recipe, we order the heat to that specification and state it on the certificate.
3Physical and mechanical data
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.70-8.03 g/cm³ | 0.278-0.290 lb/in³ |
| Elastic modulus | 190-210 GPa | 27,557-30,458 ksi |
| Poisson's ratio | 0.27-0.30 | 0.27-0.30 |
Mechanical properties
AISI 8822H is not sold at a single strength level. The numbers depend on delivery condition, so the table is arranged by condition.
| Condition | Hardness | Tensile strength | Yield strength | Elongation |
|---|---|---|---|---|
| Annealed for machining | 170-217 HBW | 550-700 MPa | 340-450 MPa | 20 % min |
| Normalized | 190-240 HBW | 650-830 MPa | 400-550 MPa | 16 % min |
| Carburized case | 58-63 HRC | |||
| Core, carburized, quenched, tempered | 30-45 HRC | 950-1300 MPa | 700-1000 MPa | 10-14 % |
Typical values for guidance. Core properties fall as section size rises, because the cooling rate at mid-radius drops. For a contractual property table on your section, send the drawing and we will return the values we can certify.
Hardenability
Hardenability is what you are buying when you specify the H grade. It is controlled by the Jominy band in SAE J1268 and checked on the heat rather than on the finished part. We supply the mill's measured Jominy curve with every heat of 8822H, so the hardness at the J distance matching your critical section can be checked before machining starts.
4Heat treatment of AISI 8822H
The usual route for a forged 8822H part is forge, normalize, rough machine, carburize, quench, temper, finish grind. An anneal goes in before machining when the part is heavily cut.
| Operation | Temperature | Cooling | Purpose |
|---|---|---|---|
| Forging | 1150-1200 °C (2100-2190 °F), finish above 900 °C | Still air or controlled furnace cool by section | Close porosity, refine cast structure, develop grain flow |
| Normalizing | 900-925 °C (1650-1700 °F) | Air | Even grain size before carburizing, less distortion |
| Annealing | 845-870 °C (1550-1600 °F) | Slow furnace cool | Soften to 170-217 HBW for heavy machining |
| Carburizing | 900-925 °C (1650-1700 °F) | Hold to required case depth | Raise surface carbon to about 0.80-1.00 % |
| Hardening | Direct quench, or reheat to 815-845 °C (1500-1550 °F) | Oil quench | Form martensite in the case |
| Tempering | 150-200 °C (300-400 °F) | Air | Relieve quench stress, hold case hardness |
Reheat quenching gives finer grain and better dimensional control than direct quenching, at the cost of an extra cycle. On rings over roughly 1500 mm outside diameter we suggest reheat quench with a press quench fixture. Free-quenched rings of that size tend to go out of round by more than the finish machining allowance can take out.
Machining and welding
AISI 8822H machines best annealed, or normalized and tempered. Machinability is broadly similar to AISI 8620. Heavy cutting should be finished before carburizing. Grinding is normally the only operation carried out after hardening.
Welding is possible in the annealed or normalized condition with low-hydrogen consumables, preheat around 200 to 300 °C and post-weld heat treatment. Do not weld a carburized and hardened part. The case will crack.
5AISI 8822H forged forms and sizes we supply
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging works rather than a stockist. Everything below is forged to order from your drawing or dimensions, in AISI 8822H and in the other grades listed on this site.
| Product form | Size range | Typical use |
|---|---|---|
| Forged round bars and rods | 80-1200 mm dia, length to 8000 mm | Shaft and pinion blanks |
| Square, rectangular, flat and hex bars | 80-1000 mm thickness, length to 8000 mm | Machined components, die blocks |
| Seamless rolled rings | 300-4000 mm OD, height to 1000 mm | Ring gears, bearing races, flanges |
| Forged rings | 200-3000 mm OD | Gear rims, spacer rings |
| Hollow bars, sleeves, bushings, cylinders | 200-2500 mm OD, ID from 100 mm | Bushings, housings, casings, barrels |
| Blocks, discs, plates | 50-800 mm thick, to 2500 mm across | Gear blanks, planet carriers |
| Gear shafts, pinion shafts, spindles | 100-1000 mm dia, length to 6000 mm | Gearbox input and output shafts |
| Maximum single piece weight | 20,000 kg |
Delivery conditions available: as forged, normalized, annealed, normalized and tempered, or quenched and tempered. Machining allowance is agreed on the drawing. We can also supply rough machined or finish machined parts to print.
6AISI 8822H equivalent and comparable grades
There is no exact international twin for AISI 8822H. Its molybdenum level sits above most European and Japanese case-hardening grades of similar carbon content. The grades below are the ones published cross-reference tables list against it.
| Standard | Designation | Closeness of match |
|---|---|---|
| SAE / AISI (USA) | 8822H, 8822 | Same grade |
| UNS (USA) | H88220 for the H grade, G88220 for 8822 | Same grade |
| ASTM (USA) | A304, A322, A331, A519 bar and tube specifications | Product specifications covering the grade |
| DIN / W.-Nr. (Germany) | 1.6543 (21NiCrMo2-2) | Nearest, lower Mo than 8822H |
| B.S. (UK) | 805A20 | Nearest, lower Mo than 8822H |
| JIS (Japan) | SNCM220 / SNCM220H | Nearest, lower Mo than 8822H |
| GB/T 3077 (China) | 20CrNiMo | Nearest Chinese grade, check Mo range |
These are the closest published matches, not drop-in replacements. 8822H is a hardenability-guaranteed grade, so a steel with similar chemistry can still fall outside the J band and leave a soft core in a thick section. Send us the drawing and the critical section and we will say whether a substitution is safe or whether the specified grade should be held.
7AISI 8822H against 8620H and 4320H
These three carburizing grades cover most heavy gear work, and we are asked to compare them regularly. They form a hardenability ladder.
| Property | AISI 8620H | AISI 8822H | AISI 4320H |
|---|---|---|---|
| Carbon | 0.17-0.23 % | 0.19-0.25 % | 0.17-0.23 % |
| Nickel | 0.35-0.75 % | 0.35-0.75 % | 1.55-2.00 % |
| Chromium | 0.35-0.65 % | 0.35-0.65 % | 0.35-0.65 % |
| Molybdenum | 0.15-0.25 % | 0.30-0.40 % | 0.20-0.30 % |
| Hardenability | Moderate | High | High, with tougher core |
| Core toughness | Good | Good | Best of the three |
| Relative cost | Lowest | Middle | Highest |
| Suited to | Small and medium gears, thin sections | Heavy gears and shafts in thick sections | Shock-loaded gears, aerospace and marine drivetrain |
In practice the move from 8620H to 8822H happens when the section is too thick to harden through. The move from 8822H to 4320H happens when the failure mode is impact rather than contact fatigue and the extra nickel earns its cost.
8Where AISI 8822H is used
8822H is a drivetrain steel. Most applications want the same thing from it: a surface that resists contact fatigue and wear, over a core strong enough to carry bending load in a thick section.
- Gearing. Ring gears, bull gears, pinions, gear rims, planetary gears and planet carriers.
- Shafts. Gearbox input and output shafts, pinion shafts, spindles, splined shafts.
- Wind energy. Main shafts, gearbox gearing and carrier forgings.
- Mining and construction. Final drive gears, swing drives, track drive components.
- Marine and industrial. Reduction gearboxes, propulsion gearing, heavy roller and bearing components.
- Off-highway and truck. Axle drive gears, differential gearing, transmission shafts.
The grade can also be run without carburizing. Quenched and tempered it behaves as a medium-strength through-hardened alloy steel, and it is occasionally specified that way for shafts that need strength but no case.
9How we forge AISI 8822H
We produce AISI 8822H by the open-die route. Carburized gear and shaft forgings need a sound centre and continuous grain flow, which a cast blank or a piece cut from plate will not give.
Route
- Steelmaking. Electric arc furnace, ladle refining and vacuum degassing, to keep hydrogen low and inclusions fine. Certified to the H band chemistry and the Jominy requirement.
- Heating. Ingot or billet soaked to 1150-1200 °C with controlled ramp rates on heavy sections.
- Forging. Upsetting and drawing on hydraulic press to reach the required forging ratio, finishing above 900 °C. Rings are then expanded on a ring rolling mill.
- Post-forge heat treatment. Normalize, normalize and temper, or anneal as ordered.
- Machining. Rough or finish machining to the drawing, with agreed allowance for the customer's carburizing.
- Inspection and release. Chemistry, mechanical testing, hardness, dimensional check and ultrasonic examination before packing.
Forging reduction ratio is agreed case by case. On carburized gear blanks we normally hold a minimum 3:1 ratio, or the ratio stated on your specification where that is higher.
10Testing, certification and packing
| Check | Method or standard |
|---|---|
| Chemical analysis | Spectrometer, ladle and product analysis |
| Hardenability | Jominy end-quench, SAE J1268 and ASTM A255 |
| Tensile and yield | ASTM A370, ISO 6892-1 |
| Impact toughness | Charpy V-notch, ASTM E23, temperature per order |
| Hardness | Brinell or Rockwell, ASTM E10 and E18 |
| Ultrasonic examination | ASTM A388, acceptance class per order |
| Grain size and cleanliness | ASTM E112, ASTM E45 |
| Dimensional | Per drawing, report issued with the release |
| Certification | EN 10204 3.1 as standard, 3.2 with third-party witness on request |
Third-party inspection by SGS, BV, TUV or your own inspector is welcome and can be arranged at any hold point. Parts are rust-preventive coated, then packed in seaworthy wooden cases or on steel pallets for container or bulk shipment from Shanghai or Zhangjiagang.
11Common questions about AISI 8822H
What is AISI 8822H steel?
AISI 8822H is a nickel-chromium-molybdenum carburizing alloy steel containing about 0.19 to 0.25 % carbon, 0.35 to 0.75 % nickel, 0.35 to 0.65 % chromium and 0.30 to 0.40 % molybdenum. The H suffix means the steel is ordered against a guaranteed hardenability band under SAE J1268 rather than against chemistry alone. Carburized, quenched and tempered it reaches roughly 58 to 63 HRC at the surface over a tough core, which is why it is used for heavy-duty gears, pinions and drivetrain shafts.
What is the difference between AISI 8822 and AISI 8822H?
AISI 8822 (UNS G88220) is ordered against a chemical analysis. AISI 8822H (UNS H88220) is ordered against a Jominy end-quench hardenability band, and its chemical limits are widened slightly so the mill can meet that band. For thick forgings and large gear blanks the H grade is the safer choice, because it guarantees hardening depth rather than composition alone.
What is the chemical composition of AISI 8822H?
Carbon 0.19 to 0.25 %, manganese 0.70 to 1.05 %, silicon 0.15 to 0.35 %, nickel 0.35 to 0.75 %, chromium 0.35 to 0.65 %, molybdenum 0.30 to 0.40 %, phosphorus 0.035 % max, sulfur 0.040 % max, balance iron. The full band is set out in Table 1 above.
What hardness can AISI 8822H reach?
Carburized at 900 to 925 °C, oil quenched and tempered at 150 to 200 °C, AISI 8822H reaches a case hardness of about 58 to 63 HRC with a core of roughly 30 to 45 HRC depending on section size. Annealed for machining it is normally delivered at 170 to 217 HBW.
What is the equivalent grade of AISI 8822H?
Published cross-reference tables list DIN / W.-Nr. 1.6543 (21NiCrMo2-2), B.S. 805A20 and JIS SNCM220H against AISI 8822H, with GB/T 3077 20CrNiMo as the nearest Chinese grade. None is an exact match, since 8822H carries more molybdenum than the 8620 family. Check chemistry and the hardenability band against the drawing before substituting.
Is AISI 8822H a case hardening steel?
Yes. It is a low-carbon carburizing grade, normally gas carburized, quenched and tempered at low temperature to give a hard wear-resistant case over a tough core. It can also be run without carburizing, quenched and tempered as a through-hardened medium-strength steel.
Can AISI 8822H be forged into seamless rolled rings?
Yes. Jiangyin Jiangnan Metal Co., Ltd. rolls AISI 8822H into seamless rings from about 300 mm to 4000 mm outside diameter, and open-die forges the same grade into bars, blocks, discs, sleeves, hollow bars and gear shafts up to about 20 tonnes per piece.
Is AISI 8822H weldable?
It can be welded in the annealed or normalized condition with low-hydrogen consumables, preheat around 200 to 300 °C and post-weld heat treatment. Do not weld a carburized and hardened part, because the hardened case will crack.
What is the minimum order quantity and lead time?
Single-piece trial orders are accepted. Lead time runs 25 to 40 days from drawing approval for forged and heat-treated parts, depending on size, delivery condition and machining allowance. Send a drawing or the required dimensions to sales@steelforgepieces.com for a quotation.
Should I choose 8822H or 8620H for a heavy gear?
8822H suits heavier sections. It carries roughly twice the molybdenum of 8620H and slightly more carbon, giving deeper hardenability and higher core strength in thick gear blanks. 8620H is adequate and cheaper for smaller gears in thinner sections. Table 7 above sets the two side by side with 4320H.
12Cite this page
The data on this page is maintained by the technical department of Jiangyin Jiangnan Metal Co., Ltd., an open-die forging works in Jiangyin, Jiangsu, China. If you reference it, please cite it as:
Jiangyin Jiangnan Metal Co., Ltd. (2026). AISI 8822H (SAE 8822H / UNS H88220): composition, heat treatment, equivalents and forged sizes. Retrieved from https://www.steelforgepieces.com/Alloy-Steel/AISI-8822H.html
Reference standards
- SAE J1268, Hardenability Bands for Carbon and Alloy H Steels
- SAE J404, Chemical Compositions of SAE Alloy Steels
- ASTM A304, Steel Bars, Alloy, Subject to End-Quench Hardenability Requirements
- ASTM A255, Determining Hardenability of Steel
- ASTM A388, Ultrasonic Examination of Steel Forgings
- EN 10204, Metallic Products, Types of Inspection Documents
Property values shown as typical are representative of the grade and do not replace the certified values on the mill certificate supplied with your order.
Get an AISI 8822H quotation
Send a drawing, or just the grade, dimensions, quantity and delivery condition. Quotes come from the works, so lead time and tolerance are checked before we reply.
Open-die forging works