Custom 450 Forgings (UNS S45000, ASTM A564 Type XM-25, AMS 5763, EN 1.4594)

What Custom 450 forged products can you buy?

Jiangyin Jiangnan Metal produces UNS S45000 by four routes, chosen by geometry and order size. Open-die forging covers long shafts, blocks and heavy discs. Seamless ring rolling produces rings from 200 mm to 2,500 mm outside diameter, the most common route for pump and valve housings. Closed-die forging handles repeat-volume parts such as turbine blade blanks and valve trim. Upset forging is used for short, large-section hubs and flanges. Near-net-shape dies typically remove 30-50% of the rough machining on profiled parts, which matters more in this alloy than in carbon steel because the raw material cost per kilogram is roughly ten times higher.

What is Custom 450 / UNS S45000 stainless steel?

Custom 450 is a martensitic, age-hardenable stainless steel developed to solve a specific problem: 17-4PH and the other 4%-copper precipitation-hardening grades are strong but comparatively brittle and awkward to weld, while Type 410 martensitic stainless is tough and cheap but corrodes. Custom 450 sits between them. Lowering copper to about 1.5%, raising nickel to 5-7% and adding 0.5-1.0% molybdenum produces a low-carbon martensite that is soft enough to machine and weld as delivered, then hardens through a single ageing step without any refrigeration or double treatment.

Three properties define it in service:

• Simple heat treatment. One solution treatment at 1040 °C, then one four-hour age between 482 °C and 621 °C. No sub-zero step, no austenite-conditioning cycle. Dimensional change on ageing is about −0.001 in/in (−0.1%), small enough that many parts are finish-machined before ageing.
• Corrosion resistance close to Type 304. The 14-16% chromium plus molybdenum gives markedly better resistance than 410, 416 or 420, and slightly better pitting resistance than 17-4PH, whose molybdenum is not specified.
• Toughness the copper-rich PH grades cannot match. The GE turbine specification B50A789 demands a minimum room-temperature Charpy V-notch of 50 ft·lbf (68 J) for the overaged classes, roughly double what 17-4PH is usually held to. That toughness is why the alloy became a steam and gas turbine blading material.

The alloy is ferromagnetic in every condition, because the matrix is martensite. It is not a heat-resisting alloy: the ageing reaction that creates the strength also destroys it if service temperature approaches the ageing temperature, and the lower critical point (Ac₁) is only about 632 °C.

What are the equivalents of Custom 450? (UNS S45000, XM-25, AMS 5763, 1.4594)

Buyers meet this alloy under at least ten names. All of the designations below describe the same basic 15Cr-6Ni-1.5Cu-0.8Mo-Nb chemistry, and we accept purchase orders under any of them, but they are not interchangeable in their limits, and the differences are set out in the standards comparison below.

Standards listed are the specifications most commonly invoked for forged product. Always reference the revision in force at the contract date.

What is the chemical composition of Custom 450 / UNS S45000?

The composition below is the ASTM A564 / A705 Type XM-25 requirement, and it is what we buy raw material against unless a drawing calls for a tighter band. Chromium carries the corrosion resistance; nickel keeps the martensite tough and sets the transformation temperatures; copper and niobium are the strengthening pair that responds to ageing; molybdenum improves pitting resistance and raises the tempering resistance of the matrix.

Niobium is specified as a multiple of carbon, not a fixed range. At the 0.05% C ceiling that means 0.40% Nb minimum. EN 1.4594 and GE B50A789 instead give explicit niobium ranges.

How do ASTM A564, EN 1.4594 and GE B50A789 differ?

Most suppliers present these three as interchangeable. They are not. EN 1.4594 runs lower chromium and roughly double the molybdenum of the ASTM band, and holds sulphur to half the ASTM limit. The GE turbine specification tightens carbon and sulphur much further and adds explicit trace-element ceilings. A heat bought to one of them will not automatically satisfy another.

What are the mechanical properties of Custom 450 in each condition?

Everything on this page turns on one number: the ageing temperature in degrees Fahrenheit, which is what the H-number means. H900 is four hours at 900 °F (482 °C); H1150 is four hours at 1150 °F (621 °C). Higher ageing temperature means lower strength, higher elongation, higher toughness and better resistance to stress-corrosion cracking. There is no separate hardening step; the martensite already exists after solution treatment.

Condition A, as we normally ship for machining

If your old datasheet lists only 125 ksi / 95 ksi for Custom 450, it is quoting this solution-treated row, not an aged property. Aged material is far stronger.

Aged conditions: specification minima

AC = air cool. (L) longitudinal, (T) transverse to grain flow. H1025 is listed for sections up to 200 mm, longitudinal only. Values are the published requirements of ASTM A564 / A705 Type XM-25. Confirm against the revision in force at your contract date, and note that AMS 5763, EN 10088-3 and GE B50A789 set their own acceptance values.

Typical production values

Minima are what a certificate must beat; typical bar and forging results sit well above them. The numbers below are representative published values for the alloy and are what we expect to see on a test coupon from a correctly processed heat.

Which Custom 450 condition should you specify?

Pick the highest ageing temperature that still meets your strength requirement. Every degree above the minimum you need buys toughness, ductility and stress-corrosion resistance at no extra cost; the ageing cycle is the same four hours either way.

How is Custom 450 heat treated?

Two operations, in this order, with machining between them wherever tolerances allow.

1. Solution treatment at 1040 °C ± 15 °C (1900 °F ± 25 °F), then cool rapidly. Hold roughly 30 minutes per 25 mm of section, one hour minimum. All carbides, copper and niobium go into solution and the structure transforms to martensite on cooling. Water or oil quench is preferred for heavy forgings; forced air is acceptable on thin sections and gives less distortion. Because the martensite finish temperature is around 38 °C, transformation completes at room temperature, so no refrigeration step is needed, unlike 15-5PH or PH13-8Mo.
2. Ageing for 4 hours at 482-621 °C (900-1150 °F), then air cool. One step, no intermediate conditioning. 482 °C (H900) gives peak strength; higher temperatures over-age the copper precipitates and trade strength for toughness. Hold time is measured from when the part reaches temperature; add roughly 30 minutes per additional 25 mm of section for heavy pieces.

What are the physical properties of Custom 450?

How corrosion resistant is Custom 450, and how hot can it run?

General corrosion resistance is comparable to Type 304, clearly better than the 410/416/420 martensitic family and slightly better than 17-4PH, because molybdenum is a specified element here and is not in 17-4PH. The pitting resistance equivalent number, PREN = %Cr + 3.3 × %Mo, works out at roughly 17.5 for mid-range ASTM chemistry and up to 19-21 for EN 1.4594 with its higher molybdenum. Both are below the ~32 threshold usually applied to continuous seawater immersion.

Service temperature: the rule that matters

A precipitation-hardening steel cannot be used at a temperature where its own strengthening reaction keeps running. The practical rule is to stay at least 50 °C below the ageing temperature you specified. H900 material is therefore limited to roughly 430 °C, and H1150 material can go higher, but at those temperatures long-term strength retention and creep must be verified for the specific duty. A commonly quoted general design limit for aged Custom 450 is about 425 °C (800 °F). Above Ac₁ ≈ 632 °C the alloy begins to re-austenitise and the condition is lost entirely. For sustained service above 450 °C, move to A286 / UNS S66286 or a nickel alloy such as Inconel 718.

Custom 450 vs 17-4PH, 15-5PH and PH13-8Mo: which one do you need?

This is the most common technical question we get on this grade. The short version: 17-4PH is stronger and far easier to buy; Custom 450 is tougher, more weldable and slightly more corrosion resistant. If a drawing specifies Custom 450 and someone suggests substituting 17-4PH to save money, check the toughness and weld requirements before agreeing.

The three questions that decide it

1. Does the part get welded and stay in service without re-solution treatment? Custom 450 tolerates that far better. Its low carbon and 6% nickel keep the heat-affected zone tough, and no preheat is needed.
2. Is there an impact or fracture-toughness acceptance criterion? If a Charpy minimum appears on the drawing, especially above 40 J, Custom 450 is the safer grade.
3. Do you need more than 1,240 MPa? Then Custom 450 cannot do it and 17-4PH H900 or PH13-8Mo is the answer.

How is Custom 450 forged, welded and machined?

Forging

The alloy hot works easily, noticeably easier than the nickel-base superalloys we run on the same presses. Soak and forge in the range 1150-1177 °C (2100-2150 °F), with a workable envelope of about 900-1260 °C. Finish above roughly 950 °C: below that the alloy work-hardens fast and surface cracking risk rises. Aim for a forging reduction of at least 4:1 to break down the cast structure and develop grain flow, then full anneal after forging before any solution treatment or ageing; hot work leaves a mixed structure that must be reset. Slow cooling straight from the finishing temperature is preferred over air blasting on heavy sections to avoid quench cracks.

Welding

Ease of welding is the alloy's headline advantage. All standard stainless processes apply (GTAW, GMAW, SMAW, submerged arc) and no preheat is required to prevent cracking. Use a matching filler to keep weld-metal strength in step with the parent material. Where full corrosion resistance and full properties are needed across the joint, solution treat and re-age after welding; for many repairs and non-critical joints, welding in Condition A followed by ageing alone is enough. Brazing consumables suitable for Type 304 work here, and brazing temperature should sit in the annealing range so that a separate re-anneal is not needed.

Machining and cold work

Machine in Condition A wherever possible; at ≤32 HRC the alloy behaves like other martensitic stainless of similar strength. Use positive feeds and conservative speeds; never let the tool dwell, because a rubbing edge glazes the surface. The work-hardening rate is low compared with austenitic grades, so cold forming, bending and drawing are practical without intermediate anneals, but avoid sharp bends and deep-drawing operations that concentrate strain locally.

How does Custom 450 fail, and how do you prevent it?

What can Jiangyin Jiangnan Metal forge in Custom 450?

UNS S45000 is a made-to-order grade for us: we buy the heat against your specification rather than pulling from stock, which is why the drawing and the required condition matter at enquiry stage. The envelopes below are tested limits for this alloy on our equipment, not carbon-steel limits.

Equipment used on this grade

Which standards and certificates apply?

Quality management is certified to ISO 9001:2015. Third-party witness certificates are issued through the inspection body you nominate: Lloyd's Register, DNV, Bureau Veritas, ABS, TÜV or SGS. Customers keep an unrestricted right to witness any production stage, including chemistry, heat treatment and mechanical testing.

How do you specify a Custom 450 forging order?

1. Name the material generically. Write UNS S45000 / ASTM A705 Type XM-25 for forgings, or ASTM A564 Type XM-25 for bar. A purchase order that only says "Custom 450" names a Carpenter trademark and can strictly only be filled by that mill.
2. State the aged condition and the cycle. For example H1050 (566 °C / 4 h / air cool). Naming the cycle as well as the H-number removes any argument about what was actually done.
3. Say whether we ship solution treated or aged. "Supplied in Condition A for customer machining and ageing" and "Supplied fully aged to H1050" are different parts, different prices and different lead times.
4. Send the drawing with test direction and grain flow. Above 50 mm section, state whether tensile and impact tests are longitudinal or transverse. Transverse minima are much lower; Table 5 shows the gap.
5. Define NDE and acceptance class. "UT per EN 10228-3, quality class 3" or "UT per ASTM A388 with acceptance to the purchase order". An unqualified "ultrasonic test" is not a specification.
6. Choose the certificate. EN 10204 3.1 as standard; 3.2 with a named witness where the project demands it. Say if you need multi-designation cross-certification to EN 1.4594.
7. Give quantity, date, Incoterm and destination. Quantity changes the melt route: below roughly 500 kg we consolidate onto a larger heat, which affects both price and lead time.

Drawing callout you can copy

MATERIAL:      UNS S45000 / ASTM A705 Type XM-25
               (cross-certify EN 1.4594 / X5CrNiMoCuNb14-5 if required)
CONDITION:     Solution treat 1040 °C ±15 °C, cool rapidly;
               age H1050 = 566 °C / 4 h / air cool
HARDNESS:      34 HRC min, verified at locations A, B, C
TENSILE:       1000 MPa UTS min, 930 MPa YS min, 12% el., 45% RA (longitudinal)
GRAIN FLOW:    Longitudinal, parallel to the principal axis; verify per ASTM E381
NDE:           UT per EN 10228-3 quality class 3
               PT per ASTM E165, Type I Method C
CERTIFICATE:   EN 10204 3.1 (3.2 with third-party witness if stated on the PO)
SURFACE:       Ra ≤ 1.6 µm on bearing journals, Ra ≤ 3.2 µm elsewhere
MARKING:       Heat number, condition and drawing number, low-stress stamped

Eight mistakes buyers make with Custom 450

1. Quoting ASTM B564. That is the nickel-alloy forging specification. Custom 450 is a stainless steel; use A564, A705 or SA-564.
2. Copying the 125 ksi / 95 ksi row onto an aged part. Those are Condition A minima. An H1050 part must meet 145 ksi / 135 ksi.
3. Specifying H1150 for a yield-limited design. Minimum yield falls to 515 MPa at H1150, lower than solution-treated material. Use H1100 instead.
4. Assuming EN 1.4594 and ASTM XM-25 are the same heat. Molybdenum is roughly double in the EN band and chromium is a point lower. State which one applies before we buy the material.
5. Leaving test direction unstated on a heavy forging. Transverse elongation at H900 is 6% against 10% longitudinal. The certificate can pass or fail on that word alone.
6. Welding in the aged condition and shipping. The heat-affected zone is neither properly aged nor properly solutioned. Weld in Condition A, then heat treat.
7. Ageing before final machining on tight-tolerance bores. The 0.1% shrinkage is predictable but it is not zero.
8. Treating a hardness cap as NACE compliance. It is not. See the sour-service note above.

Where is Custom 450 used?

Two worked examples

Example 1: sizing a pump shaft in H1050 against a fatigue limit

Example 2: will an H900 part survive a chloride environment?

Glossary

Custom 450 / UNS S45000 frequently asked questions

References

1. ASTM A564/A564M, Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes, ASTM International. Type XM-25 chemistry, Condition A and H-condition requirements.
2. ASTM A705/A705M, Standard Specification for Age-Hardening Stainless Steel Forgings, ASTM International.
3. ASTM A693, Standard Specification for Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet and Strip, ASTM International.
4. ASME Boiler and Pressure Vessel Code, Section II Part A, SA-564/SA-564M. Solution-treatment and age-hardening tables for S45000.
5. AMS 5763 and AMS 5773, SAE International. Corrosion-resistant steel bars, wire, forgings and rings, 15Cr-6Ni-1.5Cu-0.8Mo, precipitation hardenable.
6. EN 10088-3, Stainless steels - Part 3: Technical delivery conditions for semi-finished products, bars, rods and sections, CEN. Grade 1.4594 / X5CrNiMoCuNb14-5, conditions +AT, +P930, +P1000, +P1070.
7. EN 10250-4, Open die steel forgings for general engineering purposes - Part 4: Stainless steels, CEN.
8. General Electric specification B50A789 (GTD-450). Turbine blading classes A, B, E, F, G, H, chemistry and mechanical acceptance.
9. Carpenter Technology Corporation, Custom 450^® Stainless Technical Datasheet. Typical properties, heat treatment and fabrication guidance.
10. ASM Handbook, Volume 1: Properties and Selection: Irons, Steels and High-Performance Alloys, ASM International. Precipitation-hardening stainless steels.
11. ASM Handbook, Volume 4D: Heat Treating of Irons and Steels, ASM International.
12. ISO 15156-3 / NACE MR0175, Petroleum and natural gas industries - Materials for use in H₂S-containing environments - Part 3: Cracking-resistant CRAs and other alloys.
13. ASTM A388/A388M, Standard Practice for Ultrasonic Examination of Steel Forgings; EN 10228-3, Non-destructive testing of steel forgings - Ultrasonic testing of ferritic or martensitic steel forgings.
14. EN 10204, Metallic products - Types of inspection documents, CEN.

Standards are cited by number; always work to the revision in force at your contract date. Test results on our certificates are independent and traceable to calibrated equipment.

About the manufacturer, and how to cite this page

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, with 460 employees including 9 senior and 32 intermediate engineers. The plant runs 1 t to 9 t open-die hammers, 4,500 t and 5,000 t hydraulic presses and radial-axial ring mills up to 2,500 mm outside diameter, with in-house heat treatment, machining, mechanical testing and non-destructive examination. Alongside Custom 450 / UNS S45000 we forge carbon, alloy and tool steels, the full precipitation-hardening stainless family, duplex grades and nickel alloys. Quality management is certified to ISO 9001:2015 and material is supplied with EN 10204 3.1 certification as standard, 3.2 with third-party witness on request.

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