---
title: "Custom 450 / UNS S45000 / ASTM A564 Type XM-25 Forgings"
description: "Open-die forged Custom 450 (UNS S45000, ASTM A564 / A705 Type XM-25, AMS 5763, EN 1.4594): chemistry, H900 to H1150 mechanical properties, heat treatment, corrosion limits and ordering guidance."
canonical: "https://www.steelforgepieces.com/Nickel-Alloy/Custom-450.html"
manufacturer: "Jiangyin Jiangnan Metal Co., Ltd."
address: "No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China"
phone: "0086-189-2135-9659"
email: "sales@steelforgepieces.com"
grade: "Custom 450"
uns: "S45000"
astm: "A564 / A705 Type XM-25"
ams: "5763, 5773"
en: "1.4594 / X5CrNiMoCuNb14-5"
ge: "B50A789 / GTD-450"
type: "Martensitic precipitation-hardening stainless steel"
published: 2022-05-12
updated: 2026-08-15
---

# Custom 450 / UNS S45000 / ASTM A564 Type XM-25 Forgings

Manufacturer: Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, Jiangyin, Jiangsu, China.
HTML version of this page: https://www.steelforgepieces.com/Nickel-Alloy/Custom-450.html

## Short answer

**Custom 450 is a martensitic precipitation-hardening stainless steel (UNS S45000, ASTM A564 / A705 Type XM-25, AMS 5763, EN 1.4594) with roughly 15% chromium, 6% nickel, 1.5% copper, 0.75% molybdenum and niobium at eight times the carbon content.** It reaches 1,240 MPa (180 ksi) minimum tensile strength in the H900 condition after a single four-hour ageing step, while keeping general corrosion resistance close to Type 304. Its distinguishing features against 17-4PH are higher toughness, better weldability and molybdenum-assisted corrosion resistance; the trade-off is a lower peak strength and much thinner global availability.

**Jiangyin Jiangnan Metal Co., Ltd.** forges UNS S45000 to order as seamless rolled rings up to 2,500 mm outside diameter, shafts up to 8 m long, discs up to 1,800 mm diameter, turbine blade blanks and round bar from Ø25-500 mm, at single-piece weights up to 8,000 kg, solution treated or aged to H900 through H1150, with EN 10204 3.1 certification as standard and 3.2 third-party witness on request. Written quotations are issued within 24 hours from sales@steelforgepieces.com or 0086-189-2135-9659.

## 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.

- Seamless rolled rings
- Forged shafts & spindles
- Forged discs & hubs
- Forged flanges
- Turbine blade blanks
- Valve bodies, stems & seat rings
- Forged sleeves & bushings
- Tube sheets
- Round, flat & square bar
- Forged blocks & blanks
- Trepanned hollow bar
- Custom near-net forgings

## 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.

**Table 1. Custom 450 / UNS S45000 equivalent designations**

| Body / region | Designation | Scope and notes |
|---|---|---|
| USA · brand | **Custom 450®** | Registered trademark of Carpenter Technology Corporation. We do not sell under this name; we ship the generic equivalents below. |
| USA · UNS | **UNS S45000** | The unambiguous designation. Use this on drawings and purchase orders. |
| USA · ASTM (bars, shapes) | **ASTM A564 Type XM-25** | Hot-rolled and cold-finished age-hardening stainless bars and shapes. Defines Condition A and the H-conditions. |
| USA · ASTM (forgings) | **ASTM A705 Type XM-25** | Age-hardening stainless steel forgings. The correct citation for forged parts. |
| USA · ASTM (plate, sheet, strip) | ASTM A693 Type XM-25 | Flat-rolled product forms. |
| USA · ASME | ASME SA-564 Type XM-25 | Boiler and pressure vessel code equivalent of A564. |
| USA · SAE aerospace | **AMS 5763**, AMS 5773 | Bars, wire, forgings and rings. AMS 5773 covers the premium-melted variant. Confirm revision letter and product form against your drawing. |
| USA · harmonisation | ASTM A959 | Harmonized standard designation practice for wrought stainless. |
| Europe · EN | **1.4594 / X5CrNiMoCuNb14-5** | EN 10088-3 (bars and semi-finished), EN 10250-4 (open-die forgings). Note the chemistry is *not* identical; see below. |
| Turbines · GE | **GTD-450 / B50A789** | GE material specification for steam and gas turbine blading, classes A, B, E, F, G, H. Tighter carbon, sulphur and niobium than ASTM. |
| China | 04Cr15Ni7Cu2MoNbVN | Chinese turbine-blade steel designation matching the GTD-450 class G chemistry band. |
| Trade names | Alloy 450 · C450 · 450 stainless | Informal names in common use for the same UNS number. |

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.

**Table 2. Chemical composition, UNS S45000 (wt %, ASTM A564 / A705 Type XM-25)**

| Element | Min | Max | Why it is there |
|---|---|---|---|
| **Carbon (C)** | - | 0.05 | Kept low so chromium stays in solution for corrosion resistance and the martensite stays tough |
| **Manganese (Mn)** | - | 1.00 | Deoxidiser, sulphur control |
| **Silicon (Si)** | - | 1.00 | Deoxidiser |
| **Phosphorus (P)** | - | 0.030 | Residual; embrittles grain boundaries |
| **Sulphur (S)** | - | 0.030 | Residual; MnS inclusions initiate pitting and lower transverse toughness |
| **Chromium (Cr)** | 14.00 | 16.00 | Passive film; the reason it is stainless |
| **Nickel (Ni)** | 5.00 | 7.00 | Toughness; sets Ms / Mf so transformation completes above room temperature |
| **Copper (Cu)** | 1.25 | 1.75 | Primary ageing element; forms fine ε-copper precipitates |
| **Molybdenum (Mo)** | 0.50 | 1.00 | Pitting and crevice resistance; resistance to softening on ageing |
| **Niobium (Nb, Cb)** | 8 × C | - | Stabiliser; co-precipitates with copper and refines grain |
| **Iron (Fe)** | Balance | 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.

**Table 3. Chemistry limits by standard (wt %; single figures are maxima)**

| Element | ASTM A564 XM-25 (USA general) | EN 1.4594 (Europe) | GE B50A789 cl. E / F / H (Turbine) | GE B50A789 cl. G (Turbine) |
|---|---|---|---|---|
| Carbon | 0.05 | 0.07 | 0.025-0.045 | 0.03-0.05 |
| Manganese | 1.00 | 1.00 | 1.00 | 0.30-0.80 |
| Silicon | 1.00 | 0.70 (tighter) | 1.00 | 0.20-0.50 |
| Phosphorus | 0.030 | 0.040 | 0.025 | 0.020 |
| Sulphur | 0.030 | 0.015 (tighter) | 0.005 (tighter) | 0.005 |
| Chromium | 14.0-16.0 | 13.0-15.0 (lower) | 14.0-16.0 | 14.0-16.0 |
| Nickel | 5.0-7.0 | 5.0-6.0 | 6.0-7.0 | 6.2-6.8 |
| Copper | 1.25-1.75 | 1.20-2.00 | 1.25-1.75 | 1.35-1.75 |
| Molybdenum | 0.50-1.00 | 1.20-2.00 (≈2×) | 0.50-1.00 | 0.60-1.00 |
| Niobium | ≥ 8 × C | 0.15-0.60 | 0.40-0.75 (14 × C min) | 8 × C - 15 × C |
| Nitrogen / trace | not specified | not specified | N 0.10, Al 0.10, Ti 0.05 | N 0.10, Al 0.10, Ti 0.03 |

## 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

**Table 4. Solution-treated condition (Condition A), ASTM A564 / A705 Type XM-25**

| Property | Requirement | Note |
|---|---|---|
| Solution treatment | 1040 °C ± 15 °C | 1900 °F ± 25 °F, then cool rapidly |
| Tensile strength | ≥ 860 MPa (125 ksi) | Maximum 1,140 MPa (165 ksi) applies to sizes up to 13 mm |
| Yield strength, 0.2% | ≥ 655 MPa (95 ksi) | Already above many alloy steels in the quenched-and-tempered state |
| Elongation (2 in / 4D) | ≥ 10% |   |
| Reduction of area | ≥ 40% |   |
| Hardness | ≤ 32 HRC / ≤ 321 HB | This is a *maximum*; Condition A is the machining condition |

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

**Table 5. Minimum mechanical properties after ageing, ASTM A564 / A705 Type XM-25, sections up to 300 mm**

| Condition | Ageing | UTS min | YS 0.2% min | El. min (L) | RA min (L) | El. / RA min (T) | Hardness min |
|---|---|---|---|---|---|---|---|
| **H900** | 482 °C / 4 h / AC | 1,240 MPa / 180 ksi | 1,170 MPa / 170 ksi | 10% | 40% | 6% / 20% | 39 HRC · 363 HB |
| **H950** | 510 °C / 4 h / AC | 1,170 MPa / 170 ksi | 1,100 MPa / 160 ksi | 10% | 40% | 7% / 22% | 37 HRC · 341 HB |
| **H1000** | 540 °C / 4 h / AC | 1,100 MPa / 160 ksi | 1,035 MPa / 150 ksi | 12% | 45% | 8% / 27% | 36 HRC · 331 HB |
| **H1025** | 552 °C / 4 h / AC | 1,035 MPa / 150 ksi | 965 MPa / 140 ksi | 12% | 45% | - | 34 HRC · 321 HB |
| **H1050** | 566 °C / 4 h / AC | 1,000 MPa / 145 ksi | 930 MPa / 135 ksi | 12% | 45% | 9% / 30% | 34 HRC · 321 HB |
| **H1100** | 593 °C / 4 h / AC | 895 MPa / 130 ksi | 725 MPa / 105 ksi | 16% | 50% | 11% / 30% | 30 HRC · 285 HB |
| **H1150** | 621 °C / 4 h / AC | 860 MPa / 125 ksi | 515 MPa / 75 ksi | 18% | 55% | 12% / 35% | 26 HRC · 262 HB |

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.

**Table 6. Typical (not minimum) room-temperature properties**

| Condition | UTS | YS 0.2% | Elongation | Hardness |
|---|---|---|---|---|
| Solution treated (A) | 979 MPa · 142 ksi | 814 MPa · 118 ksi | 13% | 28 HRC |
| H900 | 1,351 MPa · 196 ksi | 1,296 MPa · 188 ksi | 14% | 42.5 HRC |
| H950 | 1,289 MPa · 187 ksi | 1,269 MPa · 184 ksi | 16% | 41.5 HRC |
| H1000 | 1,193 MPa · 173 ksi | 1,165 MPa · 169 ksi | 17% | 39 HRC |
| H1050 | 1,103 MPa · 160 ksi | 1,048 MPa · 152 ksi | 20% | 37 HRC |
| H1150 | 979 MPa · 142 ksi | 634 MPa · 92 ksi | 23% | 28 HRC |

## 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.

**Table 7. Choosing between H900 and H1150**

| Condition | Specify it when… | Avoid it when… | Typical parts |
|---|---|---|---|
| **H900** | Peak strength and hardness govern; loading is static and the environment is mild | Chlorides, hydrogen or impact loading are present | Highly loaded shafts, tooling, fasteners |
| **H950** | A small toughness gain over H900 is worth 70 MPa of strength | Rarely the deciding choice; most buyers take H900 or H1000 | Aerospace fittings |
| **H1000** | The usual high-strength production choice: 1,100 MPa with 12% elongation | Severe chloride SCC exposure | Pump shafts, impellers, high-pressure trim |
| **H1025** | An intermediate step is needed to land on a target hardness band | Section over 200 mm; the ASTM row does not cover it | Machined hydraulic parts |
| **H1050** | The best general balance for forgings: 1,000 MPa, 12% elongation, 34 HRC | You need more than 930 MPa yield | Valve bodies, rings, discs, general forgings |
| **H1100** | Heavy sections needing through-thickness consistency and good toughness | Yield strength above 725 MPa is required | Large discs, heavy rings, wellhead parts |
| **H1150** | Toughness, ductility and SCC resistance dominate; 18% elongation minimum | The design is yield-limited; see the note above | Turbine blading, marine hardware, severe service |

## 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.

> #### Dimensional change
> Ageing shrinks the part by about 0.001 in/in (0.1%). On a Ø200 mm bore that is 0.2 mm, enough to matter on an H7 fit, small enough to compensate in CAD. Many customers finish-machine in Condition A and age last.

> #### Critical temperatures
> Ac1 ≈ 632 °C, Ac3 ≈ 707 °C, Ms ≈ 118 °C, Mf ≈ 38 °C. Note that H1150 at 621 °C sits only 11 °C below Ac1, so furnace uniformity must be verified, or partial re-austenitising will produce fresh untempered martensite.

> #### Re-heat treatment
> Aged material can be re-solution treated and re-aged to a different condition without penalty, provided the part has not been in service above 500 °C. Always re-solution before re-ageing to a *lower* H-number; ageing does not reverse on its own.

## What are the physical properties of Custom 450?

**Table 8. Physical properties, UNS S45000**

| Property | Value | Condition / note |
|---|---|---|
| Density | 7.75 g / cm³ (0.280 lb / in³) | Room temperature; some sources quote 7.80 |
| Modulus of elasticity | 193-200 GPa (28-29 × 10³ ksi) | Tension, room temperature |
| Thermal conductivity | 15.0 W / m·K | 21 °C; 18.2 at 200 °C; 24.4 at 500 °C |
| Specific heat | 0.477 J / g·K | 23-102 °C |
| Electrical resistivity | ≈ 0.99 µΩ·m | 20 °C |
| Mean coefficient of expansion | 10.6 × 10⁻⁶ / °C | 24-93 °C; rises to ≈ 11.1 × 10⁻⁶ / °C at 24-593 °C |
| Magnetic response | Ferromagnetic | Martensitic in every condition; cannot be made non-magnetic |
| Ac1 / Ac3 | ≈ 632 °C / ≈ 707 °C | Lower and upper critical points |
| Ms / Mf | ≈ 118 °C / ≈ 38 °C | Transformation completes above room temperature |

## 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.

> #### Where it performs well
> - Atmospheric, fresh water and mild industrial exposure
> - Wet steam and condensate, the classic turbine blading duty
> - Mild organic acids, food and pharmaceutical process fluids
> - Pulp and paper liquors where 410 fails but 316L is not strong enough
> - Salt spray and humid atmospheres, splash-zone marine parts

> #### Where it should not go
> - Continuous seawater immersion; specify duplex 2205 or super duplex
> - Reducing acids (hydrochloric, dilute sulphuric)
> - High-chloride service in H900 or H950; chloride SCC risk
> - Sour service without qualification; see the note below
> - Continuous service near or above the ageing temperature

### 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](https://www.steelforgepieces.com/Stainless-Steel/A286-UNS-S66286.html) or a nickel alloy such as [Inconel 718](https://www.steelforgepieces.com/Nickel-Alloy/Inconel-718.html).

## 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.

**Table 9. Custom 450 against the other precipitation-hardening stainless grades**

| Property | Custom 450, S45000 | 17-4PH, S17400 | 15-5PH, S15500 | PH13-8Mo, S13800 | 410, S41000 |
|---|---|---|---|---|---|
| Chromium | 14-16 | 15-17.5 | 14-15.5 | 12.25-13.25 | 11.5-13.5 |
| Nickel | 5-7 | 3-5 | 3.5-5.5 | 7.5-8.5 | - |
| Copper | 1.25-1.75 | 3-5 | 2.5-4.5 | - | - |
| Molybdenum | 0.5-1.0 (specified) | not specified | not specified | 2.0-2.5 | - |
| Peak UTS (min) | 1,240 MPa / H900 | 1,310 MPa / H900 | 1,310 MPa / H900 | 1,520 MPa / H950 | ≈ 690 MPa |
| Ductile end (min UTS) | 860 MPa · 18% el. | 930 MPa · 16% el. | 930 MPa | 1,000 MPa | - |
| Impact toughness | (Highest of the group) / 68 J min in GE classes | Moderate | Better than 17-4PH | Very good | Moderate |
| PREN (approx.) | 17.5-21 | ≈ 16-17 | ≈ 15 | ≈ 20 | ≈ 12 |
| Heat treatment | Single age, no refrigeration | Single age | Refrigeration may apply | Conditioning + refrigeration | Quench & temper |
| Weldability | Excellent, no preheat | Good | Good | Fair | Preheat required |
| Global availability | Limited, mill order | Very wide | Wide | Aerospace channels | Very wide |
| Relative cost | 2.5-3 × | 2 × | 2.5 × | 4-5 × | 1 × baseline |
| **Best at** | **Turbine blading, tough weldable PH parts** | General PH workhorse | Heavy aerospace forgings | Landing gear class | Low-cost martensitic |

### 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?

> #### Chloride stress-corrosion cracking
> **Cause:** high-strength conditions (H900, H950) under tensile stress in chloride-bearing water. **Prevention:** specify H1100 or H1150 for any chloride exposure, remove residual tensile stress, and move to duplex for immersion service.

> #### Service over-ageing
> **Cause:** running the part near or above its own ageing temperature. Strength drops progressively and does not recover. **Prevention:** keep service at least 50 °C below the ageing temperature; re-solution and re-age parts recovered from overheated service.

> #### Hydrogen embrittlement
> **Cause:** pickling, electroplating or cathodic over-protection charging hydrogen into a hard martensite. **Prevention:** bake 4-24 h at 190-220 °C after plating or pickling; prefer the over-aged conditions for plated parts.

> #### Untempered martensite from a bad age
> **Cause:** H1150 ageing in a furnace with poor uniformity. A local excursion above Ac₁ ≈ 632 °C re-austenitises the surface, which transforms on cooling into brittle fresh martensite. **Prevention:** ±5 °C uniformity survey, thermocouples on the part, chart recording on the certificate.

> #### Forging bursts and laps
> **Cause:** finishing below 950 °C, or too much reduction in one blow. **Prevention:** control finish temperature, work in incremental passes, and accept UT to ASTM A388 or EN 10228-3 with a stated class.

> #### Missing post-weld heat treatment
> **Cause:** welding aged material and returning it to service. The heat-affected zone is partly over-aged and partly re-solutioned, so properties vary across the joint. **Prevention:** weld in Condition A, then solution treat and age; or qualify the joint as welded with hardness traverses.

## 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

> #### Forging
> 1 t, 3 t, 5 t and 9 t open-die hammers; 4,500 t and 5,000 t hydraulic presses. Radial-axial ring mills to 2,500 mm OD and 6 m ring line.

> #### Heat treatment
> Bogie-hearth solution furnaces to 1,100 °C with ±5 °C uniformity; dedicated ageing furnaces 200-700 °C with ±3 °C uniformity and chart recording; water, oil and forced-air quench.

> #### Inspection
> Optical emission spectrometer, universal tensile machine, Charpy impact machine, hardness testers, magnetic particle and penetrant lines, ultrasonic flaw detection, metallographic microscope.

## Which standards and certificates apply?

> #### Material and product
> - ASTM A564 / A705 Type XM-25, ASME SA-564
> - ASTM A693 Type XM-25 (flat product)
> - AMS 5763 / AMS 5773
> - EN 10088-3 and EN 10250-4 grade 1.4594
> - GE B50A789 / GTD-450 classes on request
> - EN 10204 3.1 standard, 3.2 with third-party witness

> #### Testing and examination
> - Ultrasonic: ASTM A388, EN 10228-3, SEP 1921
> - Penetrant: ASTM E165 / ISO 3452
> - Magnetic particle: ASTM E1444 / ISO 9934
> - Tensile ASTM E8/E8M, impact ASTM E23
> - Grain size ASTM E112, macroetch ASTM E381
> - Intergranular corrosion ASTM A262 where specified

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?

> #### Steam and gas turbines
> The application that defines the grade. Under GE specification B50A789 / GTD-450 it is used for blading, blade roots and diaphragm parts, where wet-steam erosion-corrosion, high cycle fatigue and a 68 J Charpy minimum all have to be satisfied at once.

> #### Pumps and rotating equipment
> Shafts, sleeves and impellers in H1000 or H1050, where 17-4PH would be adequate for strength but the fluid is aggressive enough to want the molybdenum.

> #### Valves and pressure parts
> Bodies, stems, seat rings and trim. The forgeability and weldability suit heavy near-net bodies that will see a weld overlay or repair.

> #### Nuclear and power plant
> Fasteners, internals and pump components where the toughness margin and the simple, auditable heat treatment are worth more than peak strength.

> #### Pulp, paper and chemical process
> Suction-roll and agitator components, digester hardware, and shafts in liquors that eat 410 and outrun the strength of 316L.

> #### Marine and offshore, aerospace
> Splash-zone deck hardware and shafting; airframe and actuator fittings to AMS 5763 where a tough PH stainless is required and PH13-8Mo is over-specified.

## Two worked examples

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

> **Given.** Ø140 mm forged shaft, UNS S45000 in H1050. Fully reversed bending stress amplitude 180 MPa, as-machined surface (Ra 1.6 µm), 10⁷ cycle design life, 99% reliability.
> **Method.** For steels the lab endurance limit is approximately 0.45-0.5 × UTS. Using the H1050 minimum UTS of 1,000 MPa: S′e ≈ 0.45 × 1,000 = 450 MPa. Apply a surface factor of 0.75 for as-machined, a size factor of 0.75 for a 140 mm section, and a reliability factor of 0.81 for 99%: Se = 450 × 0.75 × 0.75 × 0.81 ≈ 205 MPa.
> **Result.** Safety factor = 205 / 180 = 1.14, technically above one, but too thin for a rotating shaft. Two fixes cost nothing in material: shot-peen the journals, which lifts the surface factor towards 1.0 and takes the factor to roughly 1.5; or increase the diameter to 150 mm, which drops the stress amplitude by about 19%. Moving up to H1000 gains only 10% on the endurance limit and costs toughness, so geometry and surface finish are the better levers.

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

> **Given.** Valve stem in UNS S45000, proposed H900 for maximum strength, service in cooling water at 60 °C with 800 mg/l chloride.
> **Assessment.** PREN at mid-range ASTM chemistry is 15 + 3.3 × 0.75 ≈ 17.5, which is adequate against general corrosion at this chloride level but leaves little pitting margin at 60 °C. The controlling risk is not pitting, it is chloride stress-corrosion cracking: H900 puts the part at 39 HRC minimum with high residual tensile stress from machining, which is the worst combination.
> **Decision.** Specify H1100. Its 895 MPa minimum UTS and 725 MPa minimum yield still cover the stem load, hardness drops to 30 HRC, and elongation rises to 16%. If the stem load genuinely needs more than 725 MPa yield, keep H1050 and remove residual stress by finishing after ageing, or change material to a duplex grade.

## Glossary

**Table 10. Terms used on this page**

| Term | Meaning |
|---|---|
| **UNS S45000** | The Unified Numbering System designation for the 15Cr-6Ni-1.5Cu-0.8Mo-Nb martensitic precipitation-hardening stainless steel. The unambiguous way to specify this alloy. |
| **XM-25** | The ASTM type designation used in A564, A693 and A705 for UNS S45000. |
| **Condition A** | Solution treated at 1040 °C ±15 °C and cooled rapidly. Minimum 860 MPa UTS, 655 MPa yield, hardness 32 HRC maximum. The machining and welding condition. |
| **H-number** | The ageing temperature in degrees Fahrenheit. H1050 means four hours at 1050 °F (566 °C), air cooled. |
| **Age hardening** | Low-temperature heat treatment that precipitates fine copper-rich particles in the martensite, raising strength without re-quenching. |
| **Over-ageing** | Ageing above the peak temperature, which coarsens the precipitates and forms reverted austenite. Strength falls, toughness and elongation rise. |
| **Reverted austenite** | Austenite that re-forms locally during high-temperature ageing. The reason H1150 yield strength drops so sharply while elongation climbs. |
| **PREN** | Pitting resistance equivalent number, %Cr + 3.3 × %Mo (+ 16 × %N). Roughly 17.5 for ASTM-band Custom 450. |
| **Ms / Mf** | Martensite start and finish temperatures, about 118 °C and 38 °C. Both above room temperature, so no refrigeration step is needed. |
| **Ac1** | The lower critical temperature, about 632 °C, at which austenite begins to form. Sets the hard ceiling on ageing and service temperature. |
| **GTD-450 / B50A789** | General Electric's turbine-blading designation and specification for this chemistry, with classes A, B, E, F, G and H. |
| **EN 10204 3.1 / 3.2** | Certificate types. 3.1 is issued by the manufacturer's own independent inspection function; 3.2 is countersigned by a third party or the buyer's representative. |

## Custom 450 / UNS S45000 frequently asked questions

### Is Custom 450 the same as UNS S45000, XM-25, AMS 5763 and EN 1.4594?

They describe the same alloy family, but they are not identical specifications. **UNS S45000** is the generic number, **ASTM A564 / A705 Type XM-25** is the American product specification, and **AMS 5763** is the aerospace equivalent. Those three share the same chemistry band. **EN 1.4594 (X5CrNiMoCuNb14-5)** is close but not the same: chromium is 13.0-15.0% rather than 14.0-16.0%, molybdenum is 1.20-2.00% rather than 0.50-1.00%, and sulphur is capped at 0.015%. Custom 450® itself is a Carpenter Technology trademark. State which specification governs, because we buy raw material to it.

### What is the difference between Custom 450 and 17-4PH?

Custom 450 has about 6% nickel, 1.5% copper and specified molybdenum; 17-4PH has about 4% nickel, 4% copper and no specified molybdenum. In practice: 17-4PH reaches a higher peak strength (1,310 MPa minimum at H900 against 1,240 MPa), is far more widely stocked and costs less. Custom 450 is tougher (GE's turbine classes demand a 68 J Charpy minimum), welds without preheat, and resists pitting slightly better thanks to the molybdenum. Choose 17-4PH for strength and availability, Custom 450 for toughness, weldability and wet-steam or mild-chloride service.

### What is the chemical composition of Custom 450?

Per ASTM A564 / A705 Type XM-25, in weight percent: carbon 0.05 max, manganese 1.00 max, silicon 1.00 max, phosphorus 0.030 max, sulphur 0.030 max, chromium 14.00-16.00, nickel 5.00-7.00, copper 1.25-1.75, molybdenum 0.50-1.00, niobium at least 8 × carbon, balance iron.

### What tensile strength does Custom 450 reach?

Minimum 1,240 MPa (180 ksi) tensile and 1,170 MPa (170 ksi) yield in the H900 condition; typical production values are around 1,350 MPa and 1,296 MPa. At the other end, H1150 requires 860 MPa (125 ksi) tensile with 18% elongation. Solution-treated material must reach 860 MPa tensile and 655 MPa yield with hardness no higher than 32 HRC.

### How is Custom 450 heat treated?

Solution treat at 1040 °C ±15 °C (1900 °F ±25 °F) and cool rapidly, then age four hours at a temperature between 482 °C and 621 °C and air cool. The H-number is that ageing temperature in Fahrenheit. There is no refrigeration step and no double-ageing cycle. Ageing shrinks the part by roughly 0.1%.

### Which condition should I order for a general forging?

H1050 is the usual answer: 1,000 MPa minimum tensile, 930 MPa yield, 12% elongation and 34 HRC. Move up to H1000 or H900 only if the design genuinely needs the strength, and down to H1100 or H1150 if toughness, chlorides or stress-corrosion cracking are the concern.

### Why is the H1150 yield strength lower than the solution-treated yield strength?

Because H1150 over-ages the alloy. At 621 °C the copper precipitates coarsen and reverted austenite forms along the martensite lath boundaries. Austenite starts to yield at low stress and then work-hardens, so the minimum yield falls to 515 MPa while tensile strength stays at 860 MPa and elongation rises to 18%. Do not specify H1150 for a deflection- or yield-limited design.

### Is Custom 450 magnetic?

Yes. The matrix is martensite in every condition, so the alloy is ferromagnetic. There is no heat treatment that makes it non-magnetic. If you need a non-magnetic high-strength stainless, look at Nitronic 50 or A286.

### What is the maximum service temperature?

Keep continuous service at least 50 °C below the ageing temperature you specified, and about 425 °C (800 °F) as a general design limit for aged material. Above that the ageing reaction continues in service and strength drops permanently. The lower critical point is around 632 °C, above which the condition is lost entirely. For hotter duty use A286 or Inconel 718.

### Can Custom 450 be welded?

Yes, and easily. It is the most weldable of the common precipitation-hardening stainless grades. No preheat is required. Use a matching filler, weld in Condition A where you can, and solution treat plus re-age afterwards when full properties and corrosion resistance are needed across the joint.

### Is Custom 450 approved for sour service under NACE MR0175?

Do not assume so. Unlike 17-4PH, which has a well-known H1150-M route with a ≤33 HRC cap, UNS S45000 does not carry the same familiar pre-qualification. Check the current edition of ISO 15156-3 against your actual H₂S partial pressure, chloride content, pH and temperature. Where the alloy is not covered, qualification testing per ISO 15156-1 Annex B or a pre-qualified alternative is required. We will supply with a hardness cap and hardness mapping, but a hardness cap is not a compliance statement.

### What is the density of Custom 450?

7.75 g/cm³ (0.280 lb/in³); some datasheets quote 7.80 g/cm³. Our weight calculator on this page uses 7.75.

### What sizes of Custom 450 forgings can you make?

Seamless rolled rings from 200 mm to 2,500 mm outside diameter with a minimum 30 mm wall, discs to 1,800 mm diameter, shafts to 8 m length, bar from Ø25 mm to Ø500 mm, and single-piece weights up to 8,000 kg. Larger envelopes are possible in other grades; ask.

### What is the lead time and minimum order?

Ten to fourteen weeks is typical for UNS S45000, because the heat is bought against your specification rather than pulled from stock. Third-party witnessed release adds one to two weeks. Below roughly 500 kg we consolidate the order onto a larger heat, which affects both price and schedule, so tell us the quantity early.

### Do you supply Custom 450 to GE B50A789 / GTD-450?

Yes, to the class stated on your order. Note that B50A789 tightens carbon to 0.025-0.045%, sulphur to 0.005% and sets explicit niobium, nitrogen, aluminium and titanium limits, so the raw material must be bought to that specification from the start; an ASTM heat cannot be re-certified into it.

## 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.

## Cite this page

Jiangyin Jiangnan Metal Co., Ltd. (2026). *Custom 450 / UNS S45000 / ASTM A564 Type XM-25 forgings: composition, mechanical properties and ordering guide.* Updated 15 August 2026. Retrieved from https://www.steelforgepieces.com/Nickel-Alloy/Custom-450.html

**Contact for technical questions or a quotation:** Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China · 0086-189-2135-9659 · sales@steelforgepieces.com · [WhatsApp](https://wa.me/8618921359659)

### Related grades we forge

- [17-4PH / S17400](https://www.steelforgepieces.com/Stainless-Steel/17-4ph.html)
- [15-5PH / S15500](https://www.steelforgepieces.com/Stainless-Steel/15-5ph.html)
- [17-7PH / S17700](https://www.steelforgepieces.com/Stainless-Steel/17-7ph.html)
- [PH13-8Mo / S13800](https://www.steelforgepieces.com/Stainless-Steel/PH13-8Mo.html)
- [All stainless grades](https://www.steelforgepieces.com/Stainless-Steel/)
- [Forged rings](https://www.steelforgepieces.com/Forging-Rings/Forging-Ring.html)
- [Forged discs](https://www.steelforgepieces.com/Forged-Disks/Forged-Disk.html)
- [Open-die forgings](https://www.steelforgepieces.com/Forging-Parts/Open-Die-Forging-Parts.html)

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Jiangyin Jiangnan Metal Co., Ltd.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone: 0086-189-2135-9659 · Email: sales@steelforgepieces.com
Source: https://www.steelforgepieces.com/Nickel-Alloy/Custom-450.html · Updated 15 August 2026