Custom 455 / UNS S45500 / XM-16 Forging Parts

What is Custom 455 / UNS S45500 stainless steel?

Custom 455 (UNS S45500) is a martensitic precipitation-hardening stainless steel developed to reach very high yield strength from a single, simple aging treatment. Its chemistry, roughly 11.75% chromium, 8.5% nickel, 2% copper, 1.2% titanium and 0.3% niobium, with carbon held below 0.05%, produces a low-carbon martensite on cooling from solution treatment. That martensite is then strengthened by fine intermetallic precipitates, principally copper-rich and Ni₃Ti-type phases, that form during a low-temperature age.

Custom 455 differs from the more common PH stainless grades in three ways:

• Higher strength than 17-4PH or 15-5PH. Peak-aged Custom 455 reaches about 1585 MPa UTS and 1516 MPa yield, roughly 20% above 17-4PH in H900, and about seven times the yield strength of annealed Type 304 (about 205 MPa).
• One-step hardening with almost no distortion. A single 4-hour hold between 482 °C and 566 °C followed by air cooling develops full strength. Longitudinal contraction from solution-treated to aged is only 0.0007-0.0012 in/in, so close-tolerance machining can be done in the soft condition and the part aged afterwards.
• Very low work-hardening rate in Condition A. Despite being martensitic at 30-35 HRC as annealed, Custom 455 cold draws, cold rolls and cold heads readily without the intermediate anneals that austenitic grades demand.

There are trade-offs. Chromium sits near 12% rather than the 16-17% of 17-4PH, so general corrosion resistance is better than the 12% chromium martensitic grades such as Type 410 but below 17-4PH and well below 316L. Charpy impact toughness at peak strength is modest, about 11 J in H900, which is why H1000 and H1050 exist. And the titanium and copper additions make the alloy more expensive per kilogram than the mainstream PH grades.

Custom 455 is ferromagnetic in every condition, since the matrix is martensitic both as annealed and as aged. It is used for high-strength shafts and spindles, springs and spring wire in larger sections than most corrosion-resistant spring materials allow, surgical and dental instruments (where it is specified under ASTM F899), aerospace fittings, valve stems, and fasteners that must combine stainless behaviour with alloy-steel strength.

What are the equivalents of Custom 455? UNS S45500, XM-16, 1.4543 and AMS 5617

Every designation in the table below refers to the same chemistry. Engineers arrive at this grade from many directions: a drawing that says AMS 5617, a European project that says 1.4543, a medical specification that says ASTM F899. They are all specifying the same alloy. Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders under any of them and issues a material test certificate listing every specification the heat satisfies.

Compiled from ASTM A564, A693, A705 and A313; SAE AMS 5617, 5860 and 5578; EN 10088-3; ASTM F899; and published producer data sheets. Verify the revision in force at your contract date.

What is the chemical composition of Custom 455 / UNS S45500?

The composition below is per ASTM A564 / A705 Type XM-16, the specification most purchase orders reference. Chromium provides passivity. Nickel and copper stabilise the martensite and contribute to precipitation. Titanium is the primary hardening addition, forming Ni₃Ti-type precipitates. Niobium controls precipitation during aging and ties up residual carbon.

Source: ASTM A564/A564M and ASTM A705/A705M Type XM-16 limits, cross-checked against SAE AMS 5617 and published producer data sheets.

A note on a widely copied error. Several supplier pages list niobium in Custom 455 at around 2%. That is incorrect. It appears to be a transcription of the copper figure. Niobium plus tantalum is limited to 0.10-0.50% in every governing specification. If a mill certificate shows niobium near 2%, the heat is not UNS S45500 and should be rejected.

How do AMS 5617, ASTM A564/A705 and ASTM F899 / EN 1.4543 differ?

The three specification families that matter for Custom 455 are not identical. The differences are small in numbers and large in consequence: a heat melted to the surgical-grade limits will satisfy the aerospace and industrial specifications automatically, but not the other way round. Our standard practice is to procure to the strictest applicable limit so a single heat can carry several designations on one certificate.

If you do not know which to specify, write UNS S45500 / ASTM A705 Type XM-16 for forgings or UNS S45500 / ASTM A564 Type XM-16 for bar. We will cross-certify to AMS 5617 chemistry and W.Nr. 1.4543 on the same certificate at no extra cost. ASTM F899 surgical certification and AMS 5617 aerospace certification are separately priced because of the additional melt control and testing.

What are the mechanical properties of Custom 455 in H900, H950, H1000 and H1050?

Custom 455 is supplied either in Condition A (solution treated, soft enough to machine) or in one of four aged conditions. The H-number is the aging temperature in degrees Fahrenheit: H900 means four hours at 900 °F (482 °C). Higher aging temperature means lower strength and higher toughness. The table below gives typical room-temperature values for a 25 mm (1 in) bar or forging section, tested longitudinally.

Typical values for 25 mm section, compiled from published producer data sheets for UNS S45500. These are typical, not guaranteed minima. See the acceptance table below.

ASTM A564 / A705 minimum acceptance values

Purchase orders are accepted against specification minima, not against typical values. The ASTM minima for Type XM-16 are lower than the typicals above, which is normal and gives the mill process latitude. Note that ASTM A564 and A705 tabulate only H900, H950 and H1000 for XM-16. H1050 is a producer condition used where maximum toughness is wanted; if you need it, say so explicitly and agree the acceptance values on the order.

Source: ASTM A564/A564M Table 3, Type XM-16. Transverse-direction minima for elongation and reduction of area are lower than the longitudinal values shown; state the test direction on your order.

Elevated-temperature tensile properties

Custom 455 loses strength progressively above about 300 °C and falls away sharply approaching the aging temperature. The values below are typical for H950 and H1000 material and should be read together with the service-temperature guidance further down this page.

About the notched tensile column. Notched tensile strength (K_t = 10) stays near 1723 MPa across H900, H1000 and H1050 while smooth UTS falls from 1585 to 1309 MPa. The notched-to-smooth ratio therefore rises from about 1.09 to 1.32 as the aging temperature increases, so the alloy becomes progressively less notch-sensitive. For a part with threads, keyways, undercuts or fillets, that trend is often more useful than the extra yield strength.

Aging condition explorer: pick a temperature, see the trade-off

Every mechanical decision on this alloy comes down to one number: the aging temperature. Drag the control below across the 482-566 °C window and watch strength trade against toughness. The coloured axis is the same device used to mark conditions in the tables above.

How is Custom 455 / UNS S45500 heat treated?

Where PH13-8Mo needs a conditioning treatment and many high-strength martensitic stainless steels need a sub-zero step, Custom 455 hardens in one step: solution treat, machine, age.

Spring and cold-worked material behaves differently. Wire and strip in the annealed or lightly drawn condition can be aged 2-4 hours at 482 °C to exceed 1742 MPa tensile strength. Heavily cold-drawn wire or cold-rolled strip in Condition C reaches peak properties in only about half an hour at 454 °C, because prior cold work accelerates precipitation. If you are ordering cold-worked stock, tell us the intended aging cycle so we can set the delivered temper correctly.

What are the physical properties of Custom 455?

The density figure has a commercial consequence. At 7.76 g/cm³ Custom 455 is slightly lighter than 316L (7.99) but close to the other PH grades, so a straight swap from 17-4PH or 15-5PH changes part weight by well under 1%. Use the forging weight calculator below to convert your geometry into an order weight.

How corrosion-resistant is Custom 455?

Custom 455 resists staining in ordinary atmospheres and shows no corrosion in fresh water. Salt-spray testing at 5% and 35 °C, and 5% ferric chloride at room temperature, show good resistance to pitting and rusting. In mild chemical environments its general corrosion resistance is better than the 12% chromium martensitic steels such as Type 410 and 430, but it does not reach 17-4PH and is well short of 316L.

With chromium near 12% and no molybdenum, the pitting resistance equivalent number (PREN ≈ Cr + 3.3 Mo) is approximately 12. That is far below the threshold for pit-free service in seawater. Treat Custom 455 as an atmospheric, fresh-water and mild-chemical alloy. For continuous chloride immersion, specify a duplex, super-duplex or 6% Mo austenitic grade instead.

Stress-corrosion cracking

Custom 455 has been evaluated with U-bend, direct-tension, C-ring and pre-cracked cantilever specimens in marine atmospheres, 20% salt spray and 3.5% sodium chloride. The alloy shows inherently good resistance to stress-corrosion cracking, and that resistance improves markedly as the aging temperature is raised. If SCC is a design concern, H1000 or H1050 is the correct specification, not H900.

Hydrogen embrittlement

Hydrogen-embrittlement susceptibility is comparable to other high-strength martensitic stainless steels. Bake 1-3 hours at 150-177 °C after any pickling or electroplating operation. Avoid cathodic over-protection. In H₂S-containing service, note that the hardness of aged Custom 455 (40-48 HRC) is far above the limits set by NACE MR0175 / ISO 15156 for sour service. Custom 455 is not a sour-service alloy in any aged condition. For those applications see Nitronic 50 or a nickel-base alloy.

For best corrosion performance, surfaces must be free of scale and embedded iron, and finished parts should be passivated in citric or nitric acid.

What is the maximum service temperature of Custom 455?

Custom 455 resists oxidation to roughly 590 °C (1100 °F), but oxidation is not the limiting factor. Over-aging is. Any prolonged exposure at or near the aging temperature will coarsen the precipitates and permanently reduce strength.

A part aged in H900 (482 °C) has a conservative continuous service ceiling of about 455 °C. The same part aged in H1050 (566 °C) can go to about 538 °C, but starts 276 MPa lower in yield strength. Where the design is temperature-limited rather than stress-limited, aging higher is usually the better trade.

Custom 455 vs 17-4PH vs PH13-8Mo vs Custom 465: which should you specify?

How do you forge, machine and weld Custom 455 / UNS S45500?

Forging

Custom 455 forges between 899 °C and 1260 °C (1650-2300 °F). For the best mechanical properties after heat treatment, stock should be soaked uniformly at 1038-1149 °C (1900-2100 °F) and the finishing temperature kept within 816-927 °C (1500-1700 °F) to control grain size. Forgings are air cooled to room temperature and then annealed before aging. Descaling after forging is done by grit blasting or acid cleaning.

A forging ratio of at least 4:1 breaks down the cast structure and gives the directional grain flow that heavy shafts and rings need. On rolled rings the ratio is achieved through the piercing and expansion sequence rather than upsetting. Near-net-shape forging typically removes 30-50% of the rough machining stock on profiled parts. That saving is larger on this alloy than on carbon steel, because both the raw material and the machining hours are expensive.

Machining

Machine in Condition A wherever possible. At 30-35 HRC the alloy cuts far more freely than at the 48 HRC of H900. Machining characteristics resemble the nickel maraging steels: use rigid tool and work support, slower surface speeds, positive rake, deliberate cuts and generous coolant. Never let a tool dwell. Carbide tooling permits two to three times the surface speed of high-speed steel and 50-100% higher feeds.

Starting values only. Multiply surface speed by 2-3 and feed by 1.5-2 for coated carbide. Adjust for machine rigidity, setup stiffness and required surface finish.

Cold working

Custom 455 cold works readily despite being martensitic as annealed. The work-hardening rate in Condition A is extremely low, which allows considerable cold drawing and cold rolling without intermediate annealing, and makes cold heading and warm heading straightforward. Deep drawing and stretch forming do need intermediate anneals, because elongation tends to localise. Cold work before aging raises both tensile and yield strength further in the hardened condition.

Welding

Custom 455 welds satisfactorily by shielded fusion and resistance processes. Oxyacetylene welding is not recommended, because carbon pickup in the weld will occur. Preheat is not required to prevent cracking. Normally, weld in the solution-annealed condition and then age directly to the required strength level. For the optimum combination of strength, ductility and corrosion resistance, solution anneal the welded part before aging. Where high welding stresses are expected, welding in the over-aged condition (aged at about 620 °C) can help, but the part must then be solution annealed before final aging.

Custom 455 / UNS S45500 forging capability at Jiangyin Jiangnan Metal Co., Ltd.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing forgings in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys since 2008. For UNS S45500 the limits below are the tested envelopes for this specific alloy, which are tighter than our carbon-steel limits because of the narrower forging window and the heat-treatment furnace uniformity this grade demands.

Max ring OD

2,500 mm

Max disc Ø

1,800 mm

Max shaft length

8 m

Max single piece

8,000 kg

Bar diameter

25-500 mm

Min ring wall

30 mm

Conditions

A · H900 · H950
H1000 · H1050

Certification

EN 10204
3.1 / 3.2

Process route: raw material to certificate

1. Raw material. Billet from a controlled melt route, heat number traced, full chemistry verified on our optical emission spectrometer against the ordered specification before the billet is released to the forge.
2. Forging. Soak at 1038-1149 °C, multi-step reduction to at least 4:1, finish between 816 and 927 °C. Ring rolling on the radial-axial mill for circumferential grain flow.
3. Cool and anneal. Air cool to room temperature, then solution anneal at 816-843 °C with rapid cooling to establish Condition A.
4. Rough machine. Cut to +2 mm stock while the material is soft, then ultrasonic test the machined body. Defects are far easier to resolve on a clean surface.
5. Age. Single 4-hour hold at the specified temperature between 482 and 566 °C in the aging furnace (±3 °C uniformity), then air cool. Chart recording retained.
6. Test. Tensile, hardness and, where ordered, Charpy V-notch on prolongations from the same heat and heat-treatment charge. Surface penetrant or magnetic-particle inspection.
7. Certify and ship. EN 10204 3.1 as standard, 3.2 with third-party witness on request. Multi-designation certificate listing every specification the heat satisfies.

Equipment qualified for this grade

What Custom 455 forged products are available?

Jiangyin Jiangnan Metal Co., Ltd. manufactures UNS S45500 parts by four routes, chosen by geometry and order volume: open-die forging for shafts, blocks and large discs; seamless ring rolling for rings from 200 mm to 2,500 mm outside diameter; closed-die forging for repeat-volume parts; and upset forging for short, large-section hubs and heads.

Which standards and quality systems apply to Custom 455 forgings?

Quality management at Jiangyin Jiangnan Metal Co., Ltd. is certified to ISO 9001:2015. For UNS S45500 the governing material specifications are ASTM A705 (forgings), ASTM A564 (bars and shapes) and AMS 5617 (aerospace bars, forgings and rings). Inspection documents are issued to EN 10204.

How do you specify a Custom 455 / UNS S45500 forging order?

Most disputes on this grade come from two omissions: not saying which condition the part should arrive in, and not saying which direction the mechanical tests are taken. The seven steps below cover both.

1. State the generic designation. Write UNS S45500 / ASTM A705 Type XM-16 for forgings, or AMS 5617 for aerospace. Ordering against the name Custom 455 alone can be read as requiring Carpenter Technology material specifically.
2. Select the condition, and say who ages it. Condition A if you will heat treat in-house after machining; H900 or H950 for maximum strength; H1000 for balance; H1050 where impact toughness and stress-corrosion resistance govern. State explicitly whether the part is supplied solution treated or in the final aged condition.
3. Supply the drawing and the machining state. A 2D drawing or 3D model with critical dimensions, tolerances, surface roughness and any grain-flow requirement, plus whether the forging is as-forged, rough machined or finish machined.
4. Define the non-destructive examination. Ultrasonic acceptance to ASTM A388, EN 10228-3 or SEP 1921 with the class stated, and surface penetrant or magnetic particle testing to ASTM E1417 / E1444.
5. Specify test direction and location. Say whether tensile, hardness and Charpy tests are longitudinal or transverse and where the prolongation is taken. Transverse acceptance values are lower; if you do not state a direction, longitudinal is assumed.
6. Specify the certificate. EN 10204 3.1 mill certificate, or 3.2 with a named third-party inspection body. Add ASTM F899 or AMS 5617 if you need those melt and cleanliness controls.
7. Give quantity, date and Incoterms. Quantity, target delivery date, destination port and terms. Standard lead time is 8-10 weeks; AMS 5617 or 3.2 witnessed orders are 12-14 weeks; forgings above 3 tonnes typically 14 weeks.

Drawing callout template for Custom 455 forgings

Copy this block into the material note on your drawing. It is written to be unambiguous under ASTM, AMS and EN purchasing practice, and it removes almost every question we would otherwise have to raise at quotation.

MATERIAL   UNS S45500 / ASTM A705 Type XM-16
           (also satisfies ASTM A564 Type XM-16, AMS 5617,
            W.Nr. 1.4543, GB 022Cr12Ni9Cu2NbTi)

CONDITION  Supplied aged H1000
           Solution 816-843 C, cool rapidly
           Age 538 C / 4 h / air cool

HARDNESS   45 HRC +/- 2, verified at locations A, B and C

TESTS      Tensile and hardness, LONGITUDINAL, from integral
           prolongation of the same heat and HT charge
           Charpy V-notch at room temperature, 3 specimens

GRAIN FLOW Continuous, following the part contour; verify by
           macroetch per ASTM E381

NDE        Ultrasonic per ASTM A388 Class B
           (or EN 10228-3 Class 3 / SEP 1921 Class C)
           Liquid penetrant per ASTM E165 on machined surfaces

SURFACE    Ra <= 1.6 um on bearing journals and seal areas
           Ra <= 3.2 um elsewhere
           Passivate per ASTM A967 after final machining

CERT       EN 10204 3.1 mill certificate
           (3.2 with third-party witness if required)

MARKING    Heat number, condition and drawing number
           low-stress stamped or vibro-etched on a
           non-functional surface

Eight mistakes engineers make when ordering Custom 455

Where is Custom 455 / UNS S45500 used?

Custom 455 is specified where a part must be both stainless and very strong, in an environment that is not marine. The following are representative service categories for the forgings we supply.

Project references and named case studies are available on request, subject to customer confidentiality agreements.

Frequently asked questions about Custom 455 / UNS S45500

Glossary

UNS S45500

Generic Unified Numbering System designation for the 12Cr-8.5Ni-2Cu-1.2Ti martensitic precipitation-hardening stainless steel that Carpenter Technology markets as Custom 455®.

XM-16

ASTM type number for UNS S45500, used in ASTM A564 (bars and shapes), A705 (forgings), A693 (plate, sheet, strip) and A313 (spring wire).

Condition A

The solution-treated delivery condition: 816-843 °C followed by rapid cooling, giving roughly 965 MPa UTS and 30-35 HRC. Soft enough to machine and cold form, ready for the single aging step.

H-number

The aging temperature in degrees Fahrenheit. H900 means four hours at 900 °F (482 °C) followed by air cooling; H1050 means four hours at 1050 °F (566 °C).

Notched tensile strength

Tensile strength measured on a specimen carrying a machined notch of stress-concentration factor K_t = 10. Custom 455 holds roughly 1723 MPa notched tensile strength across H900 to H1050, so the notched-to-smooth ratio rises as aging temperature increases, so the alloy becomes less notch-sensitive as it is aged higher.

PREN

Pitting resistance equivalent number, approximately Cr + 3.3 Mo + 16 N. Custom 455 is about 12, which places it below the threshold for chloride pit-free service.

Seamless rolled ring

A ring produced by piercing a forged billet and expanding it on a radial-axial ring mill, giving circumferential grain flow. Jiangyin Jiangnan Metal Co., Ltd. rolls Custom 455 rings to 2,500 mm outside diameter.

Forging ratio

The ratio of starting cross-sectional area to finished cross-sectional area. At least 4:1 is used on this grade to break down the cast structure and develop directional grain flow.

EN 10204 3.1 / 3.2

Inspection document types. 3.1 is issued by the manufacturer's independent quality department with actual test results; 3.2 adds the counter-signature of a third party or the purchaser's nominated inspector.

Prolongation

An integral extension forged onto the part, heat treated with it, from which mechanical test specimens are taken. This is the only way to test properties representative of the actual forging.

Technical references

Chemistry, mechanical, heat-treatment and corrosion data on this page are drawn from the published standards and engineering references below. Test results issued on our material certificates are independent and traceable to calibrated equipment.

1. ASTM A564/A564M, Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes, ASTM International, West Conshohocken, PA. Type XM-16.
2. ASTM A705/A705M, Standard Specification for Age-Hardening Stainless Steel Forgings, ASTM International. Type XM-16.
3. ASTM A693/A693M, Standard Specification for Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet, and Strip, ASTM International.
4. ASTM A313/A313M, Standard Specification for Stainless Steel Spring Wire, ASTM International.
5. SAE AMS 5617, Steel, Corrosion-Resistant, Bars, Wire, Forgings and Rings, 11.75Cr - 8.5Ni - 2.25Cu - 1.2Ti - 0.3Cb, Solution Heat Treated, Precipitation Hardenable, SAE International.
6. SAE AMS 5860, Steel, Corrosion-Resistant, Sheet, Strip and Plate (UNS S45500), SAE International.
7. ASTM F899, Standard Specification for Wrought Stainless Steels for Surgical Instruments, ASTM International.
8. ISO 7153-1, Surgical instruments. Materials. Part 1: Metals, International Organization for Standardization.
9. EN 10088-3, Stainless steels. Part 3: Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion resisting steels for general purposes, CEN, Brussels.
10. EN 10250-4, Open die steel forgings for general engineering purposes. Part 4: Stainless steels, CEN.
11. ASTM A388/A388M, Standard Practice for Ultrasonic Examination of Steel Forgings, ASTM International.
12. EN 10228-3, Non-destructive testing of steel forgings. Part 3: Ultrasonic testing of ferritic or martensitic steel forgings, CEN.
13. SEP 1921, Ultrasonic testing of steel forgings, Stahl-Eisen-Prüfblatt, Verein Deutscher Eisenhüttenleute.
14. ASTM E165/E165M and ASTM E1417/E1417M, Liquid Penetrant Testing, ASTM International.
15. ASTM E381, Standard Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings, ASTM International.
16. ASTM A967/A967M, Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts, ASTM International.
17. EN 10204, Metallic products. Types of inspection documents, CEN.
18. NACE MR0175 / ISO 15156-3, Petroleum and natural gas industries. Materials for use in H₂S-containing environments. Part 3: Cracking-resistant CRAs and other alloys.
19. ASM Specialty Handbook: Stainless Steels, J. R. Davis (ed.), ASM International, Materials Park, OH, 1994. Chapter on precipitation-hardening stainless steels.
20. ASM Handbook, Volume 1: Properties and Selection: Irons, Steels, and High-Performance Alloys, ASM International.
21. ASM Handbook, Volume 14A: Metalworking: Bulk Forming, ASM International. Open-die forging and ring rolling practice.
22. Carpenter Technology Corporation, CarTech Custom 455 Stainless technical data sheet. The originating producer data for this alloy.

Standards listed are the revisions known current at the last page review. For procurement, always reference the revision in force at your contract date. All trademarks are the property of their respective owners.

Request a quote for Custom 455 / UNS S45500 forgings

Send the drawing, the condition you need and the quantity. We respond within 24 hours with price, lead time and written confirmation of the standards the material will be certified against: ASTM A705, ASTM A564, AMS 5617 or W.Nr. 1.4543. If you are still deciding on the aging condition, tell us the service environment and loading and our engineering team will recommend one. There is no charge for that advice.