What is 1.4545 Stainless Steel?
Jan 27, 2026
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1.4545 stainless steel, commonly known as Custom 455 or UNS S45500, is a martensitic precipitation-hardening stainless steel. It is designed to achieve very high strength and hardness after aging, while maintaining good corrosion resistance and toughness. This grade is often used in aerospace, marine, and high-performance engineering applications where a combination of high strength, moderate corrosion resistance, and dimensional stability is required.
This high-strength precipitation-hardening grade is standardized under key international systems.
| Standard | Equivalent Grade |
|---|---|
| EN (Europe) | 1.4545 |
| ASTM/AISI (USA) | Custom 455, UNS S45500 |
| Common Name | Custom 455 |
Its composition includes chromium, nickel, copper, and niobium/tantalum for precipitation hardening.
| Element | C | Si | Mn | Cr | Ni | Cu | Nb+Ta |
|---|---|---|---|---|---|---|---|
| Content (%) | ≤ 0.05 | ≤ 0.50 | ≤ 0.50 | 11.0 - 12.5 | 7.5 - 9.5 | 1.5 - 2.5 | 0.10 - 0.50 |
Mechanical properties vary significantly with heat treatment condition (e.g., Condition A, H900, H1000).
| Condition | Yield Strength (Rp0.2) | Tensile Strength (Rm) | Elongation (A) | Hardness (HRC) |
|---|---|---|---|---|
| Solution Treated (A) | ~ 1035 MPa | ~ 1170 MPa | ~ 10% | ~ 38 HRC |
| H900 | ~ 1520 MPa | ~ 1655 MPa | ~ 8% | ~ 49 HRC |
| H1000 | ~ 1380 MPa | ~ 1520 MPa | ~ 10% | ~ 46 HRC |
Key Characteristics and Applications of 1.4545 / Custom 455
Very High Strength and Hardness: Achieves tensile strengths over 1650 MPa after aging, making it one of the strongest stainless steels available.
Good Corrosion Resistance: Offers corrosion resistance comparable to Type 304 stainless steel, suitable for moderate corrosive environments.
Precipitation Hardening: Can be machined in the solution-treated condition and then aged to achieve high strength with minimal distortion.
Primary Applications:
Aerospace: High-strength fasteners, landing gear components, and structural parts.
Marine: Shafts, valves, and fittings requiring high strength and corrosion resistance.
Oil & Gas: Downhole tools and high-pressure components.
Medical: Surgical instruments and implants where strength and biocompatibility are critical.
How does Custom 455 (1.4545) compare to 17-4PH (1.4542)?
Custom 455 achieves higher strength and hardness levels than 17-4PH, with tensile strengths exceeding 1650 MPa compared to about 1310 MPa for 17-4PH (H900 condition). It also offers better toughness and ductility at similar strength levels. However, Custom 455 is more expensive and may be more challenging to machine. It is chosen for applications where maximum strength is required without sacrificing corrosion resistance.
What is the typical heat treatment for Custom 455 stainless steel?
The standard treatment involves solution treating at 815–845°C followed by rapid cooling (air or oil quench) to achieve Condition A. It is then aged at temperatures between 480–565°C (e.g., 480°C for H900, 510°C for H1000) to precipitate hardening phases. Double aging may be used to optimize properties. Machining is typically performed in the solution-treated state before final aging.
Looking for a Reliable Supplier of 1.4545 / Custom 455 Stainless Steel?
GNEE Steel supplies high-performance Custom 455 (1.4545) stainless steel in bar, wire, and forging forms, available in various heat-treated conditions to meet demanding aerospace and industrial specifications. We provide full material certification and processing support. If you have any requirements, please feel free to contact us.
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