Nickel alloy · UNS N07022 · Ni-21Cr-17Mo · age-hardenable
UNS N07022 Forgings
Seamless rolled rings, flanges, round bars, discs, shafts, sleeves and tube sheets, open-die forged to ASTM B637 / ASME SB-637.
UNS N07022 is an age-hardenable nickel-chromium-molybdenum alloy of nominal composition Ni-21Cr-17Mo, known commercially as HASTELLOY® C-22HS® alloy. It belongs to the C-type Ni-Cr-Mo family together with C-276 and C-22 and has the same resistance to uniform and localised corrosion in oxidising and reducing acids. Its strength is much higher. A solution-annealed C-type alloy yields at about 350 MPa. UNS N07022 yields at about 690 MPa after ageing and between 1,250 and 1,400 MPa after cold work, with no loss of corrosion resistance or toughness. The alloy is listed in NACE MR0175 / ISO 15156 and NACE MR0103 / ISO 17945 at the highest test levels and is used for high-strength components in severe sour oil and gas service.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We forge UNS N07022 to customer drawings: seamless rolled rings, flanges, bars, discs, shafts, sleeves, bushings and tube sheets. Parts are supplied solution treated, or solution treated and precipitation hardened, ultrasonically tested and certified to EN 10204 3.1 or 3.2. For a quotation, contact sales@steelforgepieces.com or +86 189 2135 9659.
UNS N07022 at a glance
- Grade
- UNS N07022 (also written N07022, NO7022, N7022; trade name HASTELLOY® C-22HS®)
- UNS number
- N07022
- Alloy family
- Age-hardenable nickel-chromium-molybdenum, C-type
- Nominal composition
- Ni-21Cr-17Mo (balance nickel, ~61%)
- Werkstoff / EN
- None assigned. Order to the UNS number
- Forging standard
- ASTM B637 / ASME SB-637
- Pipe & tube standard
- ASTM B983 (seamless)
- Sour service
- NACE MR0175 / ISO 15156-3 and NACE MR0103 / ISO 17945, highest test levels
- Solution anneal
- 1079 °C (1975 °F), rapid cooled
- Standard age
- 704 °C/16 h → furnace cool → 607 °C/32 h → air cool
- Delivery conditions
- ASTM B637 Type 1A, 1B, 2 or 3 (see the condition table below)
- Practical temperature ceiling
- About 400 °C for sustained service. This is a corrosion and strength alloy, not a creep alloy
- Certification
- EN 10204 3.1 as standard, 3.2 third-party witnessed on request
- Forged by
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
What UNS N07022 is, and when to specify it
The C-type nickel-chromium-molybdenum alloys (C-276, C-22, C-2000 and related grades) have been used for corrosion service in oil and gas and chemical process plant for decades. Their limitation is strength. Solution-annealed C-276 yields at around 300 to 380 MPa. That is adequate for a vessel wall but not for a tubing hanger, a mandrel or a downhole tool body carrying load in the same brine.
UNS N07022 was developed for this duty. Chromium stays at about 21% and molybdenum is raised to about 17%, which is higher than C-22 carries. Carbon is reduced to 0.010% maximum, silicon to 0.08% maximum, and the deliberate tungsten addition is removed. This composition allows the alloy to respond to a long two-stage ageing treatment, which precipitates an ordered strengthening phase without removing chromium and molybdenum from solution. Corrosion resistance is retained. Aged material has roughly double the annealed strength and cold-worked material is higher again.
Specify UNS N07022 where the service environment governs the material choice and the component also has to carry load. Typical conditions are high hydrogen sulfide and carbon dioxide partial pressures, high chloride content, elemental sulfur, service temperature above 175 °C, or a combination that falls outside the limits set for Alloy 725 or Inconel 718 in NACE MR0175 / ISO 15156. Where the environment is within the limits for 718 or 725, those alloys cost less and are more widely stocked.
Two limits are often missed on drawings. UNS N07022 is not a high-temperature alloy. It is aged between 607 °C and 704 °C, so sustained service at or above that range over-ages the material and changes the certified properties. The highest strengths quoted for the alloy also come from cold work rather than from ageing alone, and cold work cannot be applied uniformly to a large forged ring or disc. Forgings are therefore normally supplied solution treated and precipitation hardened to ASTM B637 Type 3. The cold-worked types apply to bar, wire and tube.
Chemical composition of UNS N07022
Ordering chemistry is set by ASTM B637, Table 1. The highlighted rows are the differences from C-22 (UNS N06022). Molybdenum is higher and carbon is an order of magnitude lower, which allows the alloy to be age hardened without sensitising.
| Element | Limit, % | Role in the alloy |
|---|---|---|
| Nickel (Ni) | remainder | Base element, approximately 61%. Austenitic matrix; resistance to chloride stress-corrosion cracking |
| Chromium (Cr) | 20.0–21.4 | Passive film in oxidising media; resistance to chloride pitting |
| Molybdenum (Mo) | 15.5–17.4 | Resistance in reducing acids and to crevice attack. Higher than C-22 carries |
| Carbon (C) | 0.010 max | Held very low so carbides do not deplete chromium during the long ageing cycle |
| Iron (Fe) | 1.8 max | Residual limit |
| Cobalt (Co) | 1.0 max | Residual limit; also relevant to nuclear and medical restrictions |
| Tungsten (W) | 0.8 max | Residual only. Unlike C-22 and C-276, tungsten is not a deliberate addition |
| Manganese (Mn) | 0.5 max | Deoxidiser; combines with sulfur |
| Aluminium (Al) | 0.5 max | Deoxidiser; contributes to the ageing response |
| Copper (Cu) | 0.5 max | Residual limit |
| Phosphorus (P) | 0.025 max | Kept low for hot workability |
| Sulfur (S) | 0.015 max | Kept low for hot workability and toughness |
| Tantalum (Ta) | 0.2 max | Residual limit |
| Silicon (Si) | 0.08 max | Tightly controlled. High silicon promotes unwanted intermetallic phases |
| Boron (B) | 0.006 max | Grain-boundary control |
ASTM B637 Table 1 sets no limit for niobium, titanium or zirconium in UNS N07022. The alloy originator's nominal analysis (datasheet H-2122C) differs from the ASTM window in two places. It quotes manganese 0.8% maximum and tungsten 1% maximum against 0.5% and 0.8% in ASTM B637, so material bought to the nominal sheet is not automatically inside the ASTM window. Where the purchase order names ASTM B637, the ASTM limits govern and are what we certify against. Values transcribed for guidance; confirm against the current edition of the standard when writing a purchase specification.
Ordering note. Chemistry alone does not define this material. A complete UNS N07022 purchase line states the UNS number, ASTM B637, the condition type (1A, 1B, 2 or 3), and, for sour service, a reference to NACE MR0175 / ISO 15156 so that the hardness limit is applied and recorded.
Mechanical properties: the four ASTM B637 conditions
ASTM B637 does not give UNS N07022 a single set of properties. It defines four delivery conditions, each with its own mechanical minimums and hardness rule. The condition type has to be stated on the order. Omitting it, or copying a bar condition onto a forging drawing, is a common cause of certificate rejection.
Specified minimums to ASTM B637
These are the values a mill certificate has to meet. They are minimums, not typical values.
| Condition | Heat treatment | Tensile, min | 0.2% yield, min | Elong, min | RA, min | Brinell |
|---|---|---|---|---|---|---|
| Type 1A | Solution treated + cold worked | 1103 MPa 160 ksi | 1034 MPa 150 ksi |
17 % | 50 % | 382 max |
| Type 1B | Solution treated + cold worked (heavier) | 1276 MPa 185 ksi | 1240 MPa 180 ksi |
13 % | 30 % | 425 max |
| Type 2 | Solution treated + cold worked + precipitation hardened | 1227 MPa 178 ksi | 1103 MPa 160 ksi |
15 % | 24 % | 479 max |
| Type 3 | Solution treated + precipitation hardened (no cold work; the normal forging condition) | 1000 MPa 145 ksi | 552 MPa 80 ksi |
15 % | 14 % | 228 min |
The hardness column runs in two directions. Types 1A, 1B and 2 carry a maximum Brinell figure, since hardness is the controlled variable for sulfide stress cracking resistance in cold-worked material. Type 3 carries a minimum, where hardness confirms that the age hardening has taken. Values transcribed from ASTM B637 for guidance; verify against the current edition before issuing a purchase specification.
Typical values published by the alloy originator
The specified minimums are a floor. Production material tests above them, and cold-worked material in particular is well above the Type 1B requirement. The figures below are published averages from datasheet H-2122C and are for design screening only.
| Condition | 0.2% yield | Tensile | Elong | RA | Hardness |
|---|---|---|---|---|---|
| Annealed + standard age | ≈690 MPa ≈100 ksi | — | — | — | — |
| Cold-worked bar, 43–47% | 1365 MPa 198 ksi | 1403 MPa 203.5 ksi | 16.7 % | 64.2 % | ≈42 HRC |
| Cold-worked tube, 52–53% | 1291 MPa 187.3 ksi | 1345 MPa 195 ksi | 15.1 % | — | ≈42 HRC |
Averages from the alloy originator's published test data. Individual cold-worked bar heats have been reported between 1251 and 1431 MPa (181 to 208 ksi) yield depending on diameter and the amount of cold work applied. Typical values are for guidance only. The mill test certificate issued with each forging governs acceptance.
Strength retention with temperature
Strength is retained across the temperature range used for downhole and wellhead service. The data below is for 12.7 mm diameter bar, 43% cold worked.
| Test temperature | 0.2% yield | Tensile | Elongation | Reduction of area |
|---|---|---|---|---|
| Room temperature | 1345 MPa | 1382 MPa | 18 % | 65.2 % |
| 204 °C (400 °F) | 1254 MPa | 1259 MPa | 14.6 % | 63.1 % |
| 260 °C (500 °F) | 1248 MPa | 1249 MPa | 14.1 % | 60.8 % |
Roughly 93% of room-temperature yield is retained at 260 °C. Published tensile data for the alloy extends to about 316 °C; beyond roughly 400 °C the ageing treatment itself becomes unstable and a different alloy family should be selected.
Toughness
The alloy stays tough at high strength, including at sub-zero temperature. Published Charpy V-notch results for 44% cold-worked bar are 198 J at room temperature and 207 J at −59 °C. Room-temperature fracture toughness measured to ASTM E1820 on 52–53% cold-worked material gives KJC of 189–214 MPa·m½ (172–195 ksi·in½). Compressive yield on 44% cold-worked bar is around 1124 MPa with a compressive strength of 1510 MPa.
Heat treatment and delivery condition
UNS N07022 is strengthened by a long two-stage age. The strengthening reaction is slow and the cycle cannot be shortened without losing the certified properties.
| Step | Cycle | Purpose |
|---|---|---|
| Solution anneal | 1079 °C (1975 °F), rapid cool | Dissolves precipitates, restores a fully austenitic structure before ageing |
| Low-temperature anneal | 1010 °C (1850 °F) | Alternative anneal used to reach higher strength after ageing |
| Standard two-step age | 704 °C (1300 °F) / 16 h → furnace cool → 607 °C (1125 °F) / 32 h → air cool | The specified ageing treatment. Gives ≈690 MPa yield, roughly double an annealed C-type alloy |
| Age after cold work | 607 °C (1125 °F) / 10 h → air cool | Short age applied to already cold-worked bar or tube |
Cold work plus ageing. Heavily cold-worked and aged material is not recommended by the alloy originator for severe oil-well conditions. The additional yield strength over cold work alone is small and susceptibility to hydrogen embrittlement increases. For severe sour service, take the strength from cold work or from ageing rather than from both, and confirm the intended condition with the end user before ordering.
For an open-die forging the route is forge, solution anneal at 1079 °C with a rapid quench, then run the two-step age. This produces ASTM B637 Type 3 material. Where a drawing calls for Type 1A, 1B or 2 on a forged part, the requirement has usually been carried over from a bar specification and should be reviewed before the order is placed. We raise this at the quotation stage.
Physical properties
The alloy originator's principal-features datasheet for this grade (H-2122C) publishes mechanical, corrosion and sour-service data. It does not include a physical-property table. No density, melting range, modulus or thermal conductivity figures are therefore quoted here from that source, and figures from neighbouring grades have not been substituted.
For forging weight estimation a nominal density of about 8.6 g/cm³ (0.31 lb/in³) is used for this alloy when quoting rough forged weights. Where a design calculation requires a certified modulus, expansion coefficient or thermal conductivity, state this at the enquiry stage. We will obtain measured values with the heat or source the current data sheet from the mill.
| Property | Status |
|---|---|
| Density | About 8.6 g/cm³, working figure for weight estimation. Not a certified value |
| Hardness, cold-worked 43–47% | ≈42 HRC (published average, bar and tube) |
| Hardness, ASTM B637 limits | 382 / 425 / 479 HBW maximum for Types 1A / 1B / 2; 228 HBW minimum for Type 3 |
| Melting range, modulus, thermal conductivity, expansion, resistivity | Not published by the alloy originator for this grade. Available on request against a specific heat |
| Magnetic response | Austenitic and essentially non-magnetic in all delivery conditions |
Corrosion resistance and sour-service qualification
Two data sets are relevant when comparing UNS N07022 with age-hardenable alloys carrying less molybdenum: general acid resistance, and sour-gas qualification.
Resistance to acids
Corrosion rates below are for 40% cold-worked sheet in aqueous solutions of common acids. Rates under about 0.1 mm/y are normally regarded as fully resistant for process equipment.
| Medium | Concentration | Temperature | Rate, mm/y | Rate, mpy |
|---|---|---|---|---|
| Hydrochloric acid | 1 % | boiling | 0.01 | 0.4 |
| Hydrochloric acid | 10 % | 38 °C | <0.01 | <0.1 |
| Hydrochloric acid | 20 % | 38 °C | 0.18 | 7.2 |
| Sulfuric acid | 10 % | 93 °C | 0.10 | 3.8 |
| Sulfuric acid | 40 % | 79 °C | 0.03 | 1.1 |
| Sulfuric acid | 60 % | 66 °C | 0.01 | 0.31 |
| Nitric acid | 20 % | boiling | 0.04 | 1.7 |
| Nitric acid | 60 % | 79 °C | 0.12 | 4.7 |
| Phosphoric acid | 60 % | boiling | 0.12 | 4.7 |
| Hydrofluoric acid | 5 % | 52 °C | 0.48 | 18.8 |
| ASTM G28 Method A | — | boiling | 1.08 | 42.4 |
| ASTM G28 Method B | — | boiling | 0.25 | 9.8 |
ASTM G28 A and B are accelerated intergranular attack screening tests, not service conditions. Published data, 40% cold-worked sheet. Service performance depends on aeration, velocity, contaminants and crevice geometry. Validate against your own duty.
Sour-gas qualification
UNS N07022 is listed in NACE MR0175 / ISO 15156 and NACE MR0103 / ISO 17945 at the highest test levels. The supporting test programme is summarised below.
| Test | Environment | Condition | Result |
|---|---|---|---|
| NACE TM0177 Method A | Levels II and III, 720 h, applied stress 100% of yield | Cold-worked, yield 191–233 ksi; coupled and uncoupled to carbon steel | Pass, all 8 heats |
| NACE TM0177 Method C | Level VII: 25% NaCl + 3.5 MPa H₂S + 3.5 MPa CO₂, elemental sulfur 1 and 5 g/L, 205 °C, 90-day C-ring | Cold-worked | Pass |
| NACE TM0177 Method C | Level VII-Plus: 25% NaCl + 6.9 MPa H₂S + 6.9 MPa CO₂, 288 °C, 90-day C-ring | Cold-worked | Pass, 7 heats |
| NACE TM0198 SSRT | Level VII at 205 °C, with and without elemental sulfur | Cold-worked | Ratios 0.91–1.00 against air; no secondary cracking |
| NACE TM0177 Method A | Levels II and III, 100% of yield | All-weld metal, as welded | Pass, coupled and uncoupled |
| Hydrogen embrittlement (SSRT) | 3.5% NaCl, freely corroding and cathodically charged at −850 and −1000 mV | Cold-worked | Normalised factor 0.98–1.00 against air |
Published qualification data for the alloy. Inclusion of a grade in MR0175 / ISO 15156 does not by itself qualify a part: the specific condition, hardness and environmental limits in the standard must be met and recorded on the certificate for the material as supplied.
UNS N07022 compared with C-276, C-22, Alloy 725 and Inconel 718
Five nickel alloys are commonly considered for the same components. Two are solid-solution corrosion alloys with low strength and three are age-hardenable. The table below compares them.
| Criterion | UNS N07022 | Hastelloy C-276 | Hastelloy C-22 | Alloy 725 | Inconel 718 |
|---|---|---|---|---|---|
| UNS number | N07022 | N10276 | N06022 | N07725 | N07718 |
| Nominal Cr / Mo | 21 / 17 | 16 / 16 | 21 / 13 | 21 / 8 | 19 / 3 |
| Other key elements | No W, no Nb | 4 W | 3 W | 3.5 Nb, Ti | 5 Nb, Ti, ~18 Fe |
| Strengthening | Age hardening + cold work | Solid solution only | Solid solution only | Age hardening | Age hardening |
| Specified min yield | 552 MPa aged 1240 MPa cold worked | ≈283 MPa annealed | ≈310 MPa annealed | ≈827 MPa aged | ≈1034 MPa aged |
| Reducing acid resistance | Excellent, highest Mo of the five | Excellent | Very good | Moderate | Limited |
| Oxidising acid resistance | Excellent | Moderate | Excellent | Good | Moderate |
| Severe sour service | MR0175 at the highest test levels | Excellent but low strength | Excellent but low strength | Qualified, narrower limits | Most restricted of the five |
| Forging standard | ASTM B637 | ASTM B564 / B574 | ASTM B564 / B574 | ASTM B805 / B637 | ASTM B637 |
| Relative cost | Highest | High | High | Medium-high | Lowest |
| Choose it when | Severe brine, high H₂S and high load together | Corrosion governs and the part carries little load | Oxidising and reducing conditions alternate; load is low | Sour service within its qualified limits, at lower cost | Load governs and the environment is mild |
Comparison yield figures are the specified minima from each grade's governing wrought specification in its usual delivery condition, quoted for scale rather than for design. Confirm against the applicable standard for your product form. Hastelloy® is a registered trademark of Haynes International, Inc.; Inconel® is a registered trademark of Special Metals Corporation.
Selection summary. Where Inconel 718 or Alloy 725 meets the NACE limits for the well, those alloys are cheaper and easier to source. Where the duty falls outside those limits and yield strength above 1,000 MPa is still required, UNS N07022 covers that range. Where corrosion resistance is needed but the component carries little load, C-276 or C-22 is the lower-cost choice.
Designations, equivalents and how to order
| System | Designation |
|---|---|
| UNS (USA) | N07022 |
| ASTM / ASME | B637 / SB-637 (bar, forgings, forging stock); B983 (seamless pipe and tube) |
| Trade name | HASTELLOY® C-22HS® alloy |
| Werkstoff Nr. / EN | None assigned |
| DIN / JIS / AFNOR / BS / GB | No national equivalent assigned |
| Written variants seen on enquiries | UNS NO7022 (letter O for zero), N07022, N7022, C22HS, C-22 HS, alloy C-22HS |
No European or Japanese equivalent has been assigned to this grade. Order to the UNS number and ASTM B637. HASTELLOY® and C-22HS® are registered trademarks of Haynes International, Inc. Material we produce is correctly described as UNS N07022 to ASTM B637, the same specified chemistry, manufactured independently. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with, sponsored by or endorsed by the trademark holder.
A complete purchase line
An enquiry containing the following six items can be quoted without further correspondence:
- Grade and standard. UNS N07022 to ASTM B637 / ASME SB-637
- Condition type. Type 3 for forgings. Type 1A, 1B or 2 only if the part is bar or tube
- Product form and dimensions, with machining allowance, or a drawing
- Sour-service reference. NACE MR0175 / ISO 15156 or MR0103 / ISO 17945 where applicable, so the hardness limit is applied
- NDT class. EN 10228-3, SEP 1921 class, or ASTM A388 acceptance level
- Certificate. EN 10204 3.1 or 3.2, and the witnessing body if 3.2
Applicable standards by product form
UNS N07022 has a limited set of assigned specifications. Several product forms have no ASTM specification at all, which should be checked before a drawing note is written.
| Product form or subject | ASTM | ASME |
|---|---|---|
| Forgings (our core product) | B637 | SB-637 |
| Billet, rod and bar | B637 | SB-637 |
| Seamless pipe and tube | B983 | — |
| Sheet, plate and strip | No specification assigned | |
| Welded pipe and tube | No specification assigned | |
| Fittings | No specification assigned | |
| Coated electrodes, bare rod and wire | No specification assigned | |
| Sour service | NACE MR0175 / ISO 15156-3; NACE MR0103 / ISO 17945 | |
| Sour service test methods | NACE TM0177 Methods A and C; NACE TM0198 slow strain rate | |
| Ultrasonic examination | EN 10228-3, SEP 1921, ASTM A388 | |
| Liquid penetrant examination | ASTM E165 / ASME BPVC Section V Article 6 | |
| Grain size | ASTM E112 | |
| Certification | EN 10204 3.1 or 3.2 | |
UNS N07022 forgings we produce
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory. Every item below is forged to the customer's drawing or dimensional sketch. Open-die work needs no dies, so there is no tooling charge and no minimum order quantity by piece. Single-piece and prototype orders are practical on this grade.
Size and weight capability
| Product form | Dimensional range | Unit weight |
|---|---|---|
| Seamless rolled rings | OD 200–2,000 mm, height to 600 mm | 20–3,000 kg |
| Round bars and billets | Ø80–500 mm, length to 4,000 mm | 20–2,000 kg |
| Discs and tube sheets | Ø200–1,500 mm, thickness to 400 mm | 30–3,000 kg |
| Shafts, sleeves and blocks | to 4,000 mm long | to 3,000 kg |
Indicative ranges for this grade, confirmed per enquiry. The limit on a given N07022 part is set by ingot availability and by the narrow hot-working window and high hot strength of the alloy rather than by press capacity. The envelope is smaller than the ranges we run in carbon and alloy steel. Machining allowance is normally 6–20 mm per surface depending on section size unless the drawing states otherwise. Finish-machined parts are supplied to print. Send the drawing and we will confirm feasibility before quoting.
How UNS N07022 forgings are made
- Melting. Double melting is standard for this grade. Carbon at 0.010% maximum and silicon at 0.08% maximum require a melt route selected for those limits: EAF plus AOD/VOD followed by ESR remelting, or VIM plus ESR where the specification requires it. Single-melt material is not offered for sour service.
- Ingot and billet verification. Heat chemistry is checked by spectrometer against the full ASTM B637 Table 1 window, including the carbon, silicon and tungsten limits, before any material is heated. Material bought to a nominal analysis rather than to ASTM most often fails on those three elements.
- Open-die forging. Forged on hydraulic presses with a controlled reduction ratio to close porosity and develop wrought grain flow following the part contour. The alloy has high hot strength and a narrow working window, so reduction per pass and reheat frequency are planned for the specific section rather than run to a standard schedule. Rings are ring-rolled seamless.
- Solution annealing. Held at 1079 °C (1975 °F) and rapidly cooled, which dissolves precipitates and returns the structure to a condition that will respond to ageing.
- Age hardening. The two-step cycle is 704 °C for 16 hours, furnace cooled to 607 °C for 32 hours, then air cooled. The cycle is run in a charge-loaded furnace with recorded charts. Total cycle time exceeds 48 hours and the cycle is not shortened.
- Rough or finish machining. Turned, bored, drilled and faced to the drawing, to agreed machining allowance or to final dimensions. The alloy work-hardens rapidly. Positive-rake carbide tooling, rigid setups, heavy feeds and slow speeds are used, with no dwelling in the cut.
- Non-destructive testing. Ultrasonic examination to EN 10228-3, SEP 1921 or ASTM A388 at the nominated class, plus liquid penetrant and dimensional inspection as required.
- Certification and despatch. EN 10204 3.1 mill certificate as standard, 3.2 with third-party witness (TÜV, BV, LR, SGS, DNV) on request. Hard stamped, marked, preserved and packed for sea or air freight.
Where UNS N07022 forgings are used
The application range for this alloy is narrower than for a general-purpose grade. It is used where the combination of load and environment rules out lower-cost materials.
| Sector | Components forged in UNS N07022 |
|---|---|
| Sour oil & gas production | Tubing and casing hanger bodies, mandrels, landing and lock rings, packer and completion components, downhole tool bodies, couplings for deep and ultra-deep wells |
| Wellhead and subsea | Christmas tree and wellhead body forgings, connector and hub blanks, seal sub-assemblies, subsea valve blocks and bonnets |
| Severe-service valves | Ball, gate, globe and check valve bodies and bonnets, seat rings, high-strength stems and gate blanks for high H₂S duty |
| High-strength fasteners | Stud, bolt and nut blanks where a corrosion-resistant alloy has to reach fastener strength in a sour or chloride environment |
| Chemical processing | Pump and agitator shafts, high-load reactor internals, and components exposed to mixed oxidising and reducing acids where an annealed C-type alloy is not strong enough |
| Geothermal and carbon capture | Wellhead and downhole components in hot, high-chloride, H₂S- and CO₂-bearing brines |
| Marine and desalination | High-strength shafting and fasteners in seawater and brine, where chloride pitting and crevice attack govern |
Where not to use it. UNS N07022 is not a high-temperature structural alloy. It is aged at 607 to 704 °C and is not suitable for superheater or reheater headers, ultra-supercritical steam piping, furnace internals, gas turbine hot sections, or any duty with sustained service above about 400 °C. The ageing treatment would not survive those temperatures. For those duties see Inconel 617, Haynes 230, Hastelloy X or Alloy 800HT instead.
Testing, inspection and certification
- Chemical analysis. Spectrometric heat analysis against the full ASTM B637 window, plus product analysis on the finished forging on request.
- Mechanical testing. Room-temperature tensile, yield, elongation and reduction of area per ASTM B637 for the ordered condition type. Elevated-temperature tensile and impact testing to your specification.
- Hardness. Brinell to the ASTM B637 limit for the ordered type: maximum for Types 1A, 1B and 2, minimum for Type 3. The NACE MR0175 limit is applied and recorded where sour service is specified.
- Impact testing. Charpy V-notch at room or sub-zero temperature to your acceptance criteria.
- Ultrasonic testing. EN 10228-3, SEP 1921 Class C/D/E, ASTM A388, or your nominated class.
- Surface NDT. Liquid penetrant per ASTM E165 / ASME Section V Article 6.
- Corrosion testing. ASTM G28 Method A or B, and sour-service testing to NACE TM0177 or TM0198, where the order requires it.
- Grain size and microstructure. ASTM E112 grain size, metallographic examination for intermetallic phase where specified.
- Certification. EN 10204 3.1 as standard; EN 10204 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request. Full heat traceability and hard stamping.
Frequently asked questions about UNS N07022
What is UNS N07022?
UNS N07022 is an age-hardenable nickel-chromium-molybdenum alloy with a nominal composition of Ni-21Cr-17Mo, known commercially as HASTELLOY® C-22HS® alloy. It combines the corrosion resistance of the C-type Ni-Cr-Mo family with roughly double their strength, and is used mainly for high-strength components in sour oil and gas service. Bar and forgings are covered by ASTM B637; seamless pipe and tube by ASTM B983. Jiangyin Jiangnan Metal Co., Ltd. forges UNS N07022 into rolled rings, flanges, bars, discs and shafts to customer drawing.
Is UNS N07022 the same as Hastelloy C-22?
No. Hastelloy C-22 is UNS N06022, a solid-solution alloy of roughly Ni-22Cr-13Mo-3W that cannot be strengthened by heat treatment. UNS N07022 is C-22HS, a separate age-hardenable alloy of roughly Ni-21Cr-17Mo with no deliberate tungsten addition and carbon held to 0.010% maximum. The two are not interchangeable: C-22 is ordered to ASTM B574 and B564, while N07022 is ordered to ASTM B637. Specifying the wrong UNS number will produce material with about one third of the intended yield strength.
Which standard covers UNS N07022 forgings?
ASTM B637 (ASME SB-637), Standard Specification for Precipitation-Hardening and Cold-Worked Nickel Alloy Bars, Forgings, and Forging Stock. It sets the chemistry limits, the four permitted material conditions and the mechanical minimums for each. Seamless pipe and tube in N07022 are covered by ASTM B983. There is no ASTM specification for N07022 sheet, plate, strip, welded pipe or fittings, and no EN or Werkstoff number has been assigned to the grade.
What are the Type 1A, 1B, 2 and 3 conditions in ASTM B637?
ASTM B637 defines four delivery conditions for UNS N07022. Type 1A is solution treated plus cold worked, minimum 0.2% yield 1034 MPa (150 ksi). Type 1B is solution treated plus more heavily cold worked, minimum 1240 MPa (180 ksi). Type 2 is solution treated, cold worked and precipitation hardened, minimum 1103 MPa (160 ksi). Type 3 is solution treated and precipitation hardened without cold work, minimum 552 MPa (80 ksi). Types 1A, 1B and 2 carry a maximum Brinell hardness for sour-service control; Type 3 carries a minimum. Because cold work cannot be applied uniformly to a large ring or disc, open-die forgings are normally supplied in the Type 3 condition.
What is the heat treatment for UNS N07022?
The alloy originator's published cycle is a solution anneal at 1079 °C (1975 °F) followed by a two-step age of 704 °C (1300 °F) for 16 hours, furnace cooled to 607 °C (1125 °F) for 32 hours, then air cooled. Material in this annealed and age-hardened condition typically reaches about 690 MPa (100 ksi) yield strength, roughly double an annealed C-type alloy. A low-temperature anneal at 1010 °C, or a 607 °C for 10 hours age after cold work, are used to reach higher strengths in bar and tube.
Is UNS N07022 approved for sour service?
Yes. UNS N07022 is included in NACE MR0175 / ISO 15156 and NACE MR0103 / ISO 17945 at the highest test levels. Published qualification data covers NACE TM0177 Method A at Levels II and III for 720 hours at 100% of yield, both coupled and uncoupled to carbon steel, and 90-day C-ring testing at Level VII (25% NaCl with 3.5 MPa H₂S and 3.5 MPa CO₂ plus elemental sulfur) at 205 °C, and at Level VII-Plus (6.9 MPa H₂S and 6.9 MPa CO₂) at 288 °C. The applicable hardness and condition limits in MR0175 must still be met on the certificate.
What is the maximum service temperature of UNS N07022?
UNS N07022 is a corrosion and strength alloy, not a high-temperature creep alloy. Because it is aged between 607 °C and 704 °C, prolonged exposure near or above that range will over-age the material and change its properties. Published tensile data extends to about 316 °C, and the sour-service qualification runs to 288 °C. For continuous service much above roughly 400 °C, specify a solid-solution or gamma-prime high-temperature grade such as Alloy 617, Haynes 230 or Alloy 800HT instead.
How does UNS N07022 compare with Inconel 718 and Alloy 725?
All three are age-hardenable nickel alloys used for high-strength downhole and wellhead parts. UNS N07022 carries 17% molybdenum and 21% chromium with no niobium, which gives it the best resistance of the three in reducing acids and in severe sour brines, and it is qualified in NACE MR0175 at the highest test levels. Alloy 725 has 21% chromium but only 8% molybdenum and is strengthened by niobium; it is the usual commercial alternative and is normally cheaper. Inconel 718 has 19% chromium and 3% molybdenum, is the cheapest and most widely available of the three, but is the most limited in sour service. UNS N07022 is selected where the service environment governs the choice rather than the load.
Can UNS N07022 be welded?
Yes. UNS N07022 is welded by GTAW and GMAW using matching filler. As-welded weld metal is much weaker than cold-worked base metal. Published all-weld-metal and transverse weld tensile results give about 430 to 470 MPa (62 to 68 ksi) 0.2% yield with 780 to 800 MPa (113 to 116 ksi) tensile, against 1250 to 1400 MPa in cold-worked bar. Weld metal has passed NACE TM0177 sour testing in the as-welded condition, and weld-metal Charpy energy at −196 °C is still around 160 J. Size the joint for weld-metal strength, or move the joint out of the highly stressed section.
How is UNS N07022 machined?
Treat it as a high-strength Ni-Cr-Mo alloy rather than as a stainless steel. It work-hardens rapidly and the tool has to stay under the hardened layer. Use rigid setups, sharp positive-rake carbide tooling, slow surface speeds, heavy positive feeds and generous flood coolant, with no dwelling or rubbing in the cut. In the aged condition it is harder than annealed Inconel 625 or 718, and machining time should be planned accordingly. Where possible, rough machine before ageing and finish machine after.
What sizes of UNS N07022 forgings can you supply?
Jiangyin Jiangnan Metal Co., Ltd. forges UNS N07022 seamless rolled rings, discs, bars, shafts, sleeves, bushings and tube sheets to customer drawing as open-die work. Ring outside diameters run from roughly 200 mm upward, with single-piece weights to several tonnes. The practical limit on a given part is set by ingot availability and by the narrow hot-working window of the alloy rather than by press capacity. Open-die forging needs no dies, so one-off and prototype quantities are economic and there is no tooling charge. Send a drawing to sales@steelforgepieces.com for confirmation of a specific size.
Do UNS N07022 forgings come with a material certificate?
Yes. Every UNS N07022 forging from Jiangyin Jiangnan Metal Co., Ltd. ships with an EN 10204 3.1 mill test certificate as standard, recording heat number, ladle analysis against ASTM B637, mechanical test results, hardness, heat treatment record and NDT results. EN 10204 3.2 certification witnessed by TÜV, BV, LR, SGS or DNV is available when requested at order. Ultrasonic examination is to EN 10228-3, SEP 1921 or ASTM A388 as nominated.
How long does a UNS N07022 forging take to produce?
Lead time depends on raw material availability and on the ageing cycle. If the grade is available as billet, a simple ring or disc typically runs 35 to 55 days, of which more than two days is the two-step age alone. Parts needing a new melt with ESR remelting, heavy machining, sour-service testing or third-party witnessed inspection take longer. Send the drawing and we will confirm a firm date with the quotation.
Who supplies open-die forged UNS N07022 parts in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It forges UNS N07022 and other nickel alloys, stainless steels, tool steels, alloy steels and carbon steels into seamless rolled rings, flanges, bars, discs, shafts, sleeves and tube sheets, and exports worldwide. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
Request a quotation for UNS N07022 forgings
Send a drawing, a sketch, or the dimensions and quantity. We quote open-die forgings in UNS N07022 with no tooling charge and no piece minimum. This grade is double melted and the ageing cycle runs for more than 48 hours, so an early enquiry allows a firmer delivery date to be given.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Business
- Open-die forging factory
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone / WhatsApp
- +86 189 2135 9659 (0086-189-2135-9659)
- sales@steelforgepieces.com
- Website
- www.steelforgepieces.com
Related nickel alloy grades we forge
Data source. Technical data on this page is compiled by Jiangyin Jiangnan Metal Co., Ltd. from ASTM B637 and the alloy originator's published datasheet for UNS N07022. Last updated 30 August 2026. Reference: Jiangyin Jiangnan Metal Co., Ltd., UNS N07022 Forgings, www.steelforgepieces.com. Data is offered for guidance. The mill test certificate supplied with each forging governs acceptance.