17-4PH / AISI 630 / UNS S17400 / 1.4542 Forging Parts 🇺🇸 USA:UNS S17400 · AISI 630 · ASTM A564 Type 630 · ASTM A693 Type 630 · ASTM A705 Gr 630 · AMS 5643 · AMS 5604 · AMS 5622 🇪🇺 Europe:DIN/EN 1.4542 · X5CrNiCuNb16-4 (EN 10088-3) 🇯🇵 Japan:JIS SUS 630 (JIS G 4303 / G 4318) 📜 Trademark:17-4 PH®, owned by Cleveland-Cliffs Inc. (we do not sell under this brand)

Published: 12 May 2022  |  Last reviewed and updated: 21 September 2026  |  Written and technically reviewed by the metallurgical engineering team of Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China

12 Free 17-4PH Engineering Tools on This Page

Every tool below runs entirely in your browser: nothing is uploaded and no sign-up is required. They were built by the engineering team at Jiangyin Jiangnan Metal Co., Ltd. from the same data we use to plan production. If JavaScript is unavailable, the underlying numbers are published as static tables in the Reference Data Appendix.

What Forged Products Are Available in 17-4PH / UNS S17400?

Jiangyin Jiangnan Metal produces 17-4PH forgings by four routes: open-die forging for shafts, blocks and discs up to 8 m long or 8 tonnes; seamless ring rolling for rings 200–2,500 mm outside diameter; closed-die forging for repeat-volume impellers and valve trim; and upset forging for short, large-section discs and hubs. Near-net-shape dies typically remove 30–50 % of the machining stock on complex profiles.

Open-die forging is used for long shafts, blocks and large forged discs up to 8 m length or 8 tonnes single-piece weight. Seamless ring rolling produces 17-4PH forged rings from 200 mm to 2,500 mm outside diameter, the usual route for valve flanges, pressure-housing rings and rolled-ring blanks supplied to EN 1.4542 or AMS 5643 chemistry. Closed-die forging handles repeat-volume parts such as pump impellers and valve trim where dimensional consistency outweighs maximum size. Upset forging is reserved for short, large-cross-section discs and hubs. Near-net-shape forging lowers both raw-material cost and lead time on complex profiles such as valve bodies and yoke arms. For hollow shafts with a bore above roughly 100 mm, the input bar may be supplied as a trepanned billet to cut raw-material weight and drilling time. All routes produce finished parts to ASTM A564 / A705 Type 630, AMS 5643, EN 1.4542 or JIS SUS 630 as the drawing requires.

17-4PH Development Timeline: From Invention to Industry Workhorse

17-4PH was invented by Armco in 1947, codified generically as UNS S17400 and ASTM A564 Type 630 in the 1960s, standardised in Europe as EN 1.4542 in the 1980s, and restricted by NACE MR0175 to the H1150-M condition for sour service in the 1990s. The trademark passed from Armco to AK Steel and then to Cleveland-Cliffs Inc. in 2020.

What Is 17-4PH / UNS S17400 Stainless Steel?

17-4PH is the most widely used precipitation-hardening martensitic stainless steel. A 17 % Cr – 4 % Ni – 3–5 % Cu chemistry, stabilised with Nb+Ta, transforms to martensite on cooling from 1040 °C and is then strengthened by a single low-temperature aging step that precipitates copper-rich ε particles. The result is alloy-steel strength (up to 1,310 MPa) with corrosion resistance broadly comparable to Type 304.

The defining feature of 17-4PH is the tunable strength-versus-toughness trade-off available through the choice of aging temperature. The H-number (H900, H1025, H1150 and so on) is that aging temperature in degrees Fahrenheit. Higher aging temperatures produce lower strength but higher impact toughness, better stress-corrosion cracking resistance and improved ductility. This single-grade flexibility is why 17-4PH dominates the pump and valve industries, aerospace structural parts, marine hardware, food and chemical processing equipment and many specialty industrial applications, and why Jiangyin Jiangnan Metal keeps all seven aging cycles qualified on its own heat-treatment lines.

17-4PH is martensitic and therefore magnetic in every condition (μᵣ ≈ 95 typical), which distinguishes it from the austenitic Cr-Ni stainless grades. It should not be used for prolonged service above about 315 °C (600 °F), because exposure at aging temperatures will over-age the precipitates and permanently reduce strength. For higher service temperatures see our A286 / UNS S66286 page. Where transverse toughness or cleanliness must be higher, see 15-5PH or PH 13-8 Mo.

What Are the EN 1.4542, SUS 630 and AMS 5643 Equivalents of 17-4PH?

They are the same alloy under different specifying bodies. UNS S17400, AISI 630, ASTM A564 Type 630, ASTM A693 Type 630, ASTM A705 Gr 630, AMS 5643 / 5604 / 5622, EN 1.4542 (X5CrNiCuNb16-4) and JIS SUS 630 all describe the 17Cr-4Ni-Cu-Nb chemistry. 17-4 PH® itself is a Cleveland-Cliffs trademark, not a specification.

Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders written under any of the designations below and supplies UNS S17400 / ASTM A564 Type 630 forgings certified against the equivalent specification named on the order.

What Is the Chemical Composition of 17-4PH / UNS S17400?

Per ASTM A564 Type 630: C ≤0.07, Mn ≤1.00, Si ≤1.00, P ≤0.040, S ≤0.030, Cr 15.00–17.50, Ni 3.00–5.00, Cu 3.00–5.00, Nb+Ta 0.15–0.45, balance Fe; all in weight per cent. AMS 5643, ASTM A705 Gr 630 and JIS SUS 630 use the same limits; EN 1.4542 is tighter on sulfur and silicon.

Chromium provides the corrosion resistance; the low nickel plus copper stabilises martensite with precipitation-strengthening capability; the niobium and tantalum addition prevents chromium-carbide sensitisation and controls precipitation during aging.

How Do ASTM A564, AMS 5643, EN 1.4542 and JIS SUS 630 Differ?

The mechanical minimums are effectively identical; the chemistry limits and test requirements are not. EN 1.4542 halves the sulfur limit to 0.015 %, cuts silicon to 0.70 %, narrows chromium to 15.0–17.0 % and permits up to 0.60 % molybdenum. AMS 5643 keeps ASTM chemistry but adds transverse tensile tests, clean melting, grain-flow verification and Class A ultrasonic inspection. A heat made to EN 1.4542 satisfies all four simultaneously.

Most competitor pages claim the four specifications are identical. Technically they are not. Jiangyin Jiangnan Metal Co., Ltd. procures raw stock to the most restrictive applicable limit so that a single heat can satisfy several specifications at once on the material test certificate.

Chemistry limits side by side

Bottom line on chemistry: a single 17-4PH heat meeting EN 1.4542 (the most restrictive on sulfur and silicon) automatically satisfies ASTM A564, AMS 5643 and JIS SUS 630 as well, provided the EN-permitted molybdenum is verified low. Our standard practice is to procure to the strictest applicable limit and issue a multi-designation material test certificate.

Test and quality requirements side by side

Minimum mechanical properties are essentially identical across all four standards for the same H-condition. The real differences are which tests are required, in which direction, and what non-destructive examination is performed.

Which standard should you specify?

Multi-standard material test certificates

For customers who need cross-border traceability, Jiangyin Jiangnan Metal supplies single-heat material certified to several standards at once. The material test certificate lists:

• the primary specification ordered, for example AMS 5643, EN 1.4542 or ASTM A705 Gr 630;
• every equivalent designation the chemistry and mechanicals also satisfy, stated as "also conforms to: UNS S17400, ASTM A564 Type 630, JIS SUS 630";
• heat-treatment chart recordings, lot level for AMS work, batch level for general work;
• EN 10204 3.1 as standard, or 3.2 with third-party witness (Lloyd's, DNV, BV, ABS, TÜV) on request;
• a NACE MR0175 / ISO 15156 compliance statement where applicable.

Practical takeaway: if you are unsure which standard to specify, ASTM A705 Gr 630 for forgings (or ASTM A564 Type 630 for bar) is the safest default. We cross-certify to EN 1.4542 and JIS SUS 630 on the same certificate at no extra cost. AMS 5643 aerospace certification is quoted as a separate lot because of the additional testing burden.

What Are the Mechanical Properties of 17-4PH in Every H-Condition?

Minimum properties per ASTM A564 / A705: H900 = 1,310 MPa UTS, 1,170 MPa YS, 40 HRC; H925 = 1,170 / 1,070 MPa, 38 HRC; H1025 = 1,070 / 1,000 MPa, 35 HRC; H1075 = 1,000 / 860 MPa, 32 HRC; H1100 = 965 / 795 MPa, 31 HRC; H1150 = 930 / 725 MPa, 28 HRC; H1150-M = 795 / 515 MPa, ~24 HRC. Condition A is 1,030 / 760 MPa at ≤38 HRC.

The H-number is the aging temperature in degrees Fahrenheit. Values below are minimums for longitudinal tests on bars and forgings up to 75 mm thick; thicker sections typically show a 5–8 % reduction. Charpy values are typical room-temperature results measured on our own coupons rather than specification minimums.

Data compiled by Jiangyin Jiangnan Metal Co., Ltd. from ASTM A564/A564M, ASTM A705/A705M and SAE AMS 5643, cross-checked against production test records. Hardness figures are specification minimums, except Condition A which is a maximum and H1150-M where NACE MR0175 imposes a 33 HRC ceiling. Reproduced in machine-readable form in the Reference Data Appendix.

How Do You Choose Between 17-4PH H900, H1025, H1075 and H1150?

Choose by the failure mode you fear most. H900 for maximum static strength and hardness with no impact or chloride exposure. H1025 as the general-purpose default. H1075 where fatigue governs, such as pump shafts. H1150 where impact toughness or chloride stress-corrosion resistance governs. H1150-M whenever H₂S is present, because NACE MR0175 accepts no other 17-4PH condition.

Sequence reminder. Aging is always performed after solution treatment (1040 °C then air cool to below 30 °C) and after rough machining. Because aging produces a dimensional change of under 0.1 %, tight-tolerance features should be finish-machined after aging, see ordering mistake 5.

Worked Design Calculations Using 17-4PH Data

Three worked examples show how the tabulated 17-4PH properties feed real decisions: a pump-shaft critical speed check using E = 196 GPa, a valve-stem Euler buckling check, and a modified-Goodman infinite-life fatigue check that fails and shows the three ways to fix it. All are simplified for teaching; production designs need finite-element verification and the applicable code factors.

These worked examples are simplified for teaching. Production designs must also consider temperature derating, multi-axial stress, corrosion fatigue and hydrogen, code-specified safety factors under ASME, API or EN 13445, and lifecycle cost. The engineering team at Jiangyin Jiangnan Metal Co., Ltd. is available for project-specific review.

What Are the Physical Properties of 17-4PH: Density, Thermal and Magnetic?

Density 7.75 g/cm³ (0.280 lb/in³); elastic modulus 196 GPa; shear modulus 77 GPa; Poisson's ratio 0.27; thermal conductivity ≈17.8 W/m·K; specific heat 460 J/kg·K; electrical resistivity 0.80 µΩ·m; relative magnetic permeability ≈95; Curie point ≈480 °C; melting range 1400–1440 °C.

How Corrosion-Resistant Is 17-4PH in Seawater, Acids and Sour Service?

Roughly comparable to Type 304, far better than carbon or low-alloy steel, clearly worse than 316L, which carries 2–3 % molybdenum. The PREN of 17-4PH is about 16–17, below the threshold for chloride pitting resistance in seawater, so marine use is normally limited to splash zones and intermittent immersion. Higher aging temperatures (H1100, H1150) markedly improve stress-corrosion resistance.

The H-condition changes corrosion behaviour. Low-temperature aging (H900, H925) gives the highest strength but raises susceptibility to chloride stress-corrosion cracking. High-temperature aging (H1100, H1150) reduces strength but substantially improves SCC resistance. For oil and gas service under NACE MR0175 / ISO 15156, 17-4PH is restricted to the H1150-M double-aged condition with hardness 33 HRC or lower.

For severe chloride or aggressive acid environments, consider upgrading to:

• PH 13-8 Mo (UNS S13800), premium aerospace PH grade with a molybdenum addition for better corrosion resistance and toughness;
• 904L (UNS N08904), super-austenitic for sulfuric acid service;
• Nitronic 50 (UNS S20910), high-strength austenitic widely accepted for sour service;
• 2205 or super-duplex, where continuous seawater immersion is unavoidable.

17-4PH Failure Modes and How to Prevent Them

Twelve failure modes account for almost all 17-4PH service failures: chloride stress-corrosion cracking, sulfide stress cracking, service over-aging, sigma-phase embrittlement, galvanic corrosion, chloride pitting, high-cycle fatigue, hydrogen embrittlement, incorrect heat treatment, forging bursts and laps, crevice corrosion in threads, and weld heat-affected-zone softening. Each is prevented at the specification stage rather than in service.

When Should You Choose 17-4PH Over PH 13-8 Mo, 15-5PH or 316L?

Choose 17-4PH when you need alloy-steel strength with stainless corrosion resistance at industrial cost. Choose PH 13-8 Mo when transverse toughness or corrosion margin must be higher and the budget allows two to three times the price. Choose 15-5PH for heavy aerospace forgings needing better through-thickness properties. Choose 316L when chloride corrosion, not strength, governs.

How Do You Weld, Machine and Forge 17-4PH / UNS S17400?

Weld in Condition A with ER630 or AMS 5825/5826 filler, then re-solution and age. Machine in Condition A where possible (machinability is roughly 50 % of free-machining 416) using sharp rigid carbide, positive rake, 50–80 m/min in turning and generous coolant. Forge between 1170 °C and 1230 °C, never finishing below 950 °C, with a forging ratio of at least 4:1 and slow cooling afterwards.

Welding 17-4PH

17-4PH is one of the most weldable precipitation-hardening stainless steels. GTAW and GMAW are the usual processes; matching filler per AMS 5825 / 5826 is preferred, with ER630 as the generic equivalent. Weld in Condition A, then perform a full solution treatment plus aging to restore properties in and around the weld zone. Preheat is generally unnecessary for thin sections, while thick or highly restrained joints benefit from 150 °C preheat to reduce hydrogen-cracking risk. Welding in the aged condition over-ages the heat-affected zone and can cost 20–40 % of local strength.

Machining 17-4PH

Machinability is approximately 50 % of free-machining 416 stainless and somewhat better than 304 or 316L. Machining in Condition A, at about 33 HRC, is preferred, because the alloy work-hardens less than the austenitic grades. Use sharp, rigid carbide tooling with positive rake geometry, moderate cutting speed (roughly 50–80 m/min for turning) heavy positive feed and generous coolant. The correct production sequence is rough machine in Condition A → solution treat → age → finish machine, because aging produces a dimensional change of under 0.1 % which can still exceed tolerance on close-fit features.

Forging 17-4PH

17-4PH forges within a 1170–1230 °C (2150–2250 °F) window, with a finishing temperature above 950 °C to stay out of the work-hardening and δ-ferrite regimes. Forging ratio should be at least 4:1 to break down the as-cast structure and meet AMS 5643 grain-flow requirements. The grade suits every common route, open-die forging for shafts and discs, hot ring rolling for seamless rings, closed-die forging for repeat-volume small parts and upset forging for short, large-section blanks. Near-net-shape forging is practical where 30–50 % of the rough machining can be removed by the die profile, as on compressor impeller hubs and valve bodies. Slow furnace cooling after the final blow is essential: an air or water quench from forging temperature can leave residual ferrite stringers visible on macroetch and may fail AMS 5643 cleanliness checks. For long bored shafts with bores above roughly 100 mm, ordering a trepanned billet instead of solid bar cuts material input by 40–60 % and shortens drilling time.

Production Capability: 17-4PH / UNS S17400 Forging Manufacturer

Jiangyin Jiangnan Metal Co., Ltd. forges 17-4PH shafts up to 8 m long, discs to 1,800 mm diameter, seamless rolled rings to 2,500 mm outside diameter and bar from 25 to 500 mm diameter, at single-piece weights up to 8,000 kg, with all seven aging conditions qualified in-house and ultrasonic, penetrant and magnetic-particle inspection on site.

The eight-stage 17-4PH forging process

Every 17-4PH forging leaving Jiangyin passes through these eight controlled stages. Each is logged on the heat-treatment chart and traceable on the final certificate.

Production equipment qualified for 17-4PH

The equipment below is qualified and calibrated for 17-4PH / UNS S17400 production. Sizes and weights are tested limits for this alloy, which differ from the carbon-steel limits.

Delivery performance on 17-4PH orders

Transparent delivery data, refreshed quarterly, drawn from the 387 17-4PH / UNS S17400 orders shipped between Q3 2021 and Q2 2026. The percentage is the share of orders dispatched ex-works within the stated number of weeks, measured from order confirmation.

Available forms in 17-4PH / UNS S17400

• Pump shafts up to 8 m long, usually supplied in H1025 or H1075;
• pump impellers and casings, closed-die or rough-machined open-die;
• valve bodies, valve stems and valve trim to API 6A / 6D requirements;
• forged discs and hubs up to 1,800 mm diameter;
• seamless rolled rings up to 2,500 mm outside diameter, rectangular, contoured or T-section;
• aerospace structural forgings to AMS 5643;
• marine hardware such as rudder and propeller shafts for splash-zone use;
• round, hex and square bars to ASTM A564 or AMS 5643;
• forged blocks and blanks for further machining;
• custom near-net-shape forgings to customer drawings.

Which Standards and Quality Systems Apply to 17-4PH Forgings?

For general industrial work, ASTM A705 Gr 630 (forgings) or ASTM A564 Type 630 (bars). For aerospace, AMS 5643. For Europe, EN 10088-3 / 1.4542. For Japan, JIS SUS 630. For pressure equipment, ASME SA-564 / SA-705. For H₂S service, NACE MR0175 / ISO 15156 on top of the base specification. Jiangyin Jiangnan Metal is certified to ISO 9001:2015 and issues EN 10204 3.1 certificates as standard.

Quality management certification

Material and inspection standards followed

* NACE MR0175 / ISO 15156 sour-service compliance for 17-4PH requires the H1150-M double-aged condition with hardness ≤33 HRC. EN 10204 3.2 third-party witnessed certificates are issued through client-nominated inspection bodies (Lloyd's, DNV, BV, ABS or TÜV) on a per-order basis.

Quality assurance and non-conformance policy

How to Specify a 17-4PH / UNS S17400 Forging Order

Seven steps: state the generic designation rather than the trademark; choose the H-condition; provide the drawing; state whether material ships in Condition A or aged; define NDE; state the certificate type; then give quantity, delivery date and destination. The H-condition is the one decision that does not arise with most other stainless grades, and it is where most ambiguity enters a purchase order.

Ten Mistakes Engineers Make When Ordering 17-4PH Forgings

The most frequent and most expensive errors are: specifying the trademark instead of the generic designation; using H900 in chloride service; forgetting H1150-M for sour service; welding in the aged condition; aging after finish machining; running above 315 °C; omitting the supply condition; mixing ASTM and EN limits; under-specifying NDE on fatigue-critical parts; and omitting grain-flow direction.

• Specifying "17-4 PH®" without recognising it is a registered trademark

  A purchase order requiring "17-4 PH" can technically only be filled by Cleveland-Cliffs. Independent producers cannot legally supply under that exact name.

  Fix: specify the generic designation, "UNS S17400 / ASTM A705 Gr 630" for forgings, or ASTM A564 Type 630 for bar.
• Using H900 in chloride environments

  H900 has the highest strength but the greatest susceptibility to chloride stress-corrosion cracking. Marine air, food processing and chlorinated cooling water all count as chloride service.

  Fix: use H1100 or H1150 for any chloride exposure. Verify with the H-Condition Wizard.
• Forgetting H1150-M for sour service

  Where H₂S partial pressure reaches 0.3 kPa, NACE MR0175 / ISO 15156 mandates the H1150-M double-aged condition at 33 HRC or lower. Anything else fails certification.

  Fix: run the NACE compliance checker before specifying anything for oil and gas.
• Welding 17-4PH in the aged condition

  Welding aged material over-ages the heat-affected zone and drops local strength by 20–40 %. Welds made in aged material rarely meet the original specification.

  Fix: weld in Condition A, then re-solution and age the whole welded assembly.
• Aging after finish machining

  Aging causes a dimensional change of under 0.1 %, but on a tight-tolerance feature such as an Ø80 H7 bore that still exceeds tolerance, and thin-wall parts can distort.

  Fix: rough machine in Condition A → solution treat → age → finish machine. Or compensate for the shrinkage in CAD.
• Using 17-4PH above 315 °C continuously

  Continuous service above about 315 °C progressively over-ages the precipitates, and the strength loss is permanent. Failure at design load is not uncommon.

  Fix: check the service-temperature tool, then move to A286 (≤700 °C) or Inconel 718 (≤650 °C continuous).
• Failing to state the supply condition

  Many purchase orders say "17-4PH H1025" without saying whether the part should arrive in Condition A, ready for the customer to machine and age, or in final H1025 ready to install.

  Fix: write explicitly "supplied in Condition A" or "supplied in final H1025 condition, post-machined and aged".
• Mixing ASTM and EN limits without confirmation

  EN 1.4542 has tighter sulfur (≤0.015 %) and silicon (≤0.70 %) than ASTM. Material made to ASTM limits may not satisfy the requirements for EN-marked equipment.

  Fix: when exporting to the EU or supplying CE-marked equipment, specify EN 1.4542 explicitly, or require a multi-designation certificate confirming EN compliance.
• Under-specifying NDE on fatigue-critical components

  Pump shafts and rotor components fail by surface-initiated fatigue. Specifying only "visual inspection" misses the surface defects that cut fatigue strength by 30–50 %.

  Fix: specify UT per ASTM A388 Class B plus PT per ASTM E165 on machined surfaces. For aerospace, AMS-STD-2154 Class A UT is mandatory.
• Specifying section thickness without grain-flow direction

  17-4PH is anisotropic: transverse toughness runs 10–20 % below longitudinal. On impact-critical parts the grain flow must align with the primary loading direction.

  Fix: for forged parts above 50 mm cross-section, state "longitudinal grain flow parallel to the primary axis" and verify by macroetch per ASTM E381.

How Do You Specify 17-4PH on an Engineering Drawing?

Use a callout block that names the generic designation, the H-condition with its actual cycle, the hardness band and where it is verified, the grain-flow requirement, the NDE standards, the certificate type, the surface finish and the marking requirement. The template below is accepted under ASTM, AMS, EN and JIS practice and removes almost all ordering ambiguity.

Copy this template into the material callout box on your drawing and adjust the H-condition, hardness and NDE to suit the application, see the H-Condition Wizard for selection. For sour service, replace "H1025" with "H1150-M double aged" and the hardness band with "≤33 HRC verified".

Where Is 17-4PH / UNS S17400 Used?

Pumps and valves account for about a third of 17-4PH forging demand, followed by oil and gas, aerospace structural parts, chemical and process equipment, marine hardware, and a small share in nuclear, food and research. Pump shafts in H1025 or H1075 are the single largest application worldwide.

17-4PH shipments by industry

Approximate distribution of the 387 17-4PH / UNS S17400 forging orders shipped by Jiangyin Jiangnan Metal Co., Ltd. between Q3 2021 and Q2 2026, by end-user industry. Customer names are protected by non-disclosure agreement.

Industry-specific specification guides

Each industry has its own dominant H-condition, certification pattern and design pitfalls. These six guides distil what matters in the highest-volume 17-4PH sectors, with a ready-made specification callout for each.

Representative Project Scenarios

The following are representative project scenarios rather than named references. Specific project performance data and customer references are available under non-disclosure agreement on request.

Glossary of Key 17-4PH Terms

17-4 PH®

Registered trademark of Cleveland-Cliffs Inc. (formerly AK Steel / Armco) for the original 17 % Cr – 4 % Ni – Cu precipitation-hardening stainless steel. Generic equivalents: UNS S17400, ASTM A564 Type 630, ASTM A705 Gr 630, AMS 5643, EN 1.4542, JIS SUS 630.

UNS S17400

Generic Unified Numbering System designation for the 17 % Cr – 4 % Ni – Cu – Nb precipitation-hardening martensitic stainless steel.

AISI 630

Legacy American Iron and Steel Institute designation for the 17-4PH chemistry. AISI no longer maintains active steel-numbering specifications, but AISI 630 remains widely used on legacy drawings, datasheets and procurement specifications. Fully equivalent to UNS S17400 / ASTM A564 Type 630.

ASTM A564 Type 630

Generic ASTM specification for the 17-4PH chemistry in bars and shapes.

ASTM A705 Gr 630

Generic ASTM specification for the 17-4PH chemistry in forgings, the correct specification to cite on a forging purchase order.

AMS 5643

Aerospace Material Specification for 17-4PH bars, forgings, tubing and rings; adds transverse testing, Charpy limits, clean melting, grain-flow verification and Class A ultrasonic inspection.

Condition A

Solution-annealed condition, 1040 °C then air cool to below 30 °C. Martensitic and machinable but not yet aged; hardness 38 HRC maximum.

H900

Aged at 482 °C (900 °F) for 1 hour. Highest strength: 1,310 MPa UTS, 1,170 MPa yield, 40 HRC minimum. Lowest toughness and the highest chloride SCC risk.

H1025

Aged at 552 °C (1025 °F) for 4 hours. The most common general-purpose condition: 1,070 MPa UTS, 1,000 MPa yield, 35 HRC minimum.

H1075

Aged at 580 °C (1075 °F) for 4 hours: 1,000 MPa UTS, 860 MPa yield, 32 HRC minimum. Common for pump shafts, with good fatigue resistance.

H1150

Aged at 621 °C (1150 °F) for 4 hours: 930 MPa UTS, 725 MPa yield, 28 HRC minimum. Best impact toughness and chloride SCC resistance of the single-stage conditions.

H1150-M (double aged)

Two-stage cycle, 760 °C for 2 hours then 621 °C for 4 hours, for maximum impact toughness. Hardness ≤33 HRC; the only 17-4PH condition accepted for NACE sour service.

Precipitation hardening

Strengthening mechanism in which copper-rich ε precipitates form in the martensitic matrix during aging, raising strength without a large loss of corrosion resistance.

PREN

Pitting Resistance Equivalent Number, calculated as %Cr + 3.3 × %Mo + 16 × %N. 17-4PH scores about 16–17 because it carries no deliberate molybdenum, which is why it is not used for permanent seawater immersion.

NACE MR0175 / ISO 15156

Standard governing materials for H₂S-containing oil and gas service. Limits 17-4PH to the H1150-M condition at 33 HRC maximum.

EN 1.4542

European designation X5CrNiCuNb16-4 per EN 10088-3, the same chemistry as UNS S17400 with tighter sulfur and silicon limits.

EN 10204 3.1 / 3.2

Inspection document types. A 3.1 certificate is issued by the manufacturer's own independent quality department; a 3.2 certificate is countersigned by a third-party inspector nominated by the purchaser.

Frequently Asked Questions: 17-4PH / UNS S17400

Reference Data Appendix: The Numbers Behind the Tools

Every figure used by the twelve interactive tools on this page is published below as a plain table, so the data can be read, printed, quoted or checked without running any script. The same dataset is available in machine-readable form at 17-4ph-data.json.

A1: Aging temperature versus properties (aging-curve tool)

A2: Fatigue endurance limits (S-N tool)

Surface-finish knock-down factors used in design: polished 1.0; ground 0.85–0.9; as-machined 0.6–0.8; as-forged 0.4–0.6. Apply a mean-stress correction by the modified Goodman relation. Apply a design factor of at least 2 on stress or 10 on cycles.

A3: Precipitate state by H-condition (microstructure tool)

A4: Base machining parameters (machinability tool)

A5: Indicative material price index (cost tool)

Indicative only, for relative comparison. Prices move weekly with the LME nickel and ferro-chrome indices and depend on quantity, size, certification level and lead time. Forging conversion, machining and finishing are separate cost lines. Contact sales@steelforgepieces.com for a current quotation.

A6: Strength retention against service temperature (service-temp tool)

A7: NACE MR0175 / ISO 15156 acceptance summary

A8: Forging and heat-treatment parameters

About the Manufacturer and the Authors of This Page

This page is written and maintained by the metallurgical engineering team of Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory founded in 2008 in Jiangyin, Jiangsu (one of China's largest forging clusters) exporting 17-4PH and other alloy forgings to more than 40 countries under ISO 9001:2015.

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