17-4PH (EN 1.4542 / AISI 630) is a precipitation-hardening martensitic stainless steel that combines good corrosion resistance with very high strength and hardness after heat treatment. This unique combination makes the grade especially suitable for highly loaded mechanical components where dimensional stability, repeatable performance and long service life are required.
The material is typically supplied in solution-treated condition (Condition A), after which it can be precipitation hardened (aged) to a wide range of strength levels. Common aging conditions such as H900, H1025, H1075 and H1150 allow engineers to fine-tune the balance between tensile strength, yield strength, toughness and stress corrosion resistance.
Compared to conventional austenitic stainless steels, 17-4PH offers significantly higher mechanical strength, while still maintaining good resistance against many industrial corrosive environments. This makes it a popular choice for shafts, precision parts, fasteners and structural components in demanding sectors such as mechanical engineering, hydraulics, marine applications and energy-related industries.
Because mechanical properties are strongly dependent on the selected heat treatment condition and product form, 17-4PH is usually specified together with a required condition and verified by an EN 10204 / 3.1 inspection certificate. Steelinox B.V. supplies this grade in a wide range of forms, dimensions and finishing options, including precision centerless ground shafts.
Designations & equivalents (as commonly used):
| System | Designation |
|---|---|
| W.Nr. | 1.4542 |
| EN / DIN (material name) | X5CrNiCuNb 16-4 |
| AISI | 630 |
| Common grade name | 17-4PH |
| DIN reference | DIN 17740 |
| Element | Typical range (wt. %) |
|---|---|
| C | ≤ 0.07 |
| Cr | 15.0 – 17.0 |
| Ni | 3.0 – 5.0 |
| Cu | 3.0 – 5.0 |
| Nb | 5 × C – 0.45 |
The exact melt composition is shown on the EN 10204 / 3.1 certificate supplied with the material.
| Property | Typical value |
|---|---|
| Tensile strength (Rm) | per standard / see EN 10204 3.1 certificate (depends on heat treatment) |
| Yield strength (Rp0.2) | per standard / see EN 10204 3.1 certificate (depends on heat treatment) |
| Elongation (A5) | per standard / see EN 10204 3.1 certificate |
| Hardness | per standard / see EN 10204 3.1 certificate (condition-dependent) |
| Impact toughness | per standard / see EN 10204 3.1 certificate (if specified) |
Exact values are stated on the material certificate EN 10204 / 3.1.
Common delivery / heat treatment conditions (on request): Condition A, H900, H1025, H1075, H1150.
17-4PH / 1.4542 is available in multiple semi-finished and cut-to-size forms, including round bar, forgings, blocks and flats. It is often selected for turned components and shafts where consistent machinability and repeatable aging response are required.
Stock range (indicative):
Range: on request
Steelinox B.V. supplies centerless ground bars in diameters from Ø 2 to Ø 250 mm and lengths up to 13 meters, depending on availability.
Precision grinding can be offered to a tolerance of 0.013 mm with a surface finish of Ra 35 (or better, depending on diameter and grade).
Grinding can be performed on pieces with a minimum length of 2.5 meters. Although it is possible to saw the shafts after grinding, this is not recommended due to the risk of damage.
Note: The shafts can be aligned to the tolerance specified by you.
17-4PH is strengthened through precipitation hardening (aging) after solution treatment. During aging, fine copper-rich precipitates form within the martensitic structure, significantly increasing strength and hardness. By selecting different aging temperatures (such as H900, H1025, H1075 or H1150), the mechanical properties can be tailored to the application.
Lower aging temperatures such as H900 result in maximum strength and hardness, while higher aging temperatures such as H1150 provide improved toughness and resistance to stress corrosion cracking. The optimal condition depends on load level, operating environment and safety requirements. The chosen condition should always be specified when ordering.
17-4PH offers good corrosion resistance in many industrial and atmospheric environments, comparable to standard chromium-nickel stainless steels. However, corrosion resistance is influenced by surface condition, chloride exposure and the selected aging condition. For aggressive environments, additional evaluation may be required.
The grade is frequently used in marine-related components such as propeller shafts and mechanical parts, provided that the correct heat treatment and surface condition are selected. In chloride-rich environments, higher aging conditions with improved toughness are often preferred. Material selection should always be validated for the specific exposure conditions.
Yes. Steelinox B.V. supplies centerless ground 17-4PH bars for applications requiring tight diameter tolerances, straightness and improved surface finish. Diameters from Ø 2 to Ø 250 mm and lengths up to 13 meters are available, depending on stock and processing limits.
Precision grinding can be offered to tolerances down to 0.013 mm with surface finishes of Ra 35 or better, depending on diameter and grade. Minimum grind length is 2.5 meters. Post-grinding sawing is technically possible but not recommended due to the risk of surface damage.
Mechanical properties are guaranteed according to the applicable standards and the specified heat treatment condition. Exact values for tensile strength, yield strength, hardness and elongation are confirmed on the EN 10204 / 3.1 inspection certificate supplied with each delivery.
For accurate quoting and delivery, it is recommended to specify the required product form, dimensions, heat treatment condition, tolerance class, surface finish and certification requirements. For centerless ground material, straightness and surface roughness should also be defined.
Certificates: EN 10204 / 3.1
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