What is 1.4545 Stainless Steel?
Jan 27, 2026
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1.4545 stainless steel, also known by UNS S45000 (Custom 450) or S45500 (Custom 455), is a martensitic precipitation-hardening stainless steel. It offers a good combination of high strength, moderate corrosion resistance, and excellent toughness. This grade is often used in aerospace, marine, and chemical applications where high strength-to-weight ratio and resistance to stress corrosion cracking are required.
This versatile high-strength grade is recognized under various international designations.
| Standard | Equivalent Grade |
|---|---|
| EN (Europe) | 1.4545 |
| ASTM/AISI (USA) | Custom 450, UNS S45000 |
| Alternative | Custom 455, UNS S45500 |
Its composition includes chromium, nickel, molybdenum, and copper for a balance of strength and corrosion resistance.
| Element | C | Si | Mn | Cr | Ni | Mo | Cu | Nb/Ta |
|---|---|---|---|---|---|---|---|---|
| Content (%) | ≤ 0.05 | ≤ 1.0 | ≤ 1.0 | 14.0 - 16.0 | 5.0 - 7.0 | 0.5 - 1.0 | 1.25 - 1.75 | 0.5 - 0.9 |
Mechanical properties vary significantly with heat treatment.
| Condition | Yield Strength (Rp0.2) | Tensile Strength (Rm) | Elongation (A) | Hardness (HRC) |
|---|---|---|---|---|
| Annealed | ~ 690 MPa | ~ 1035 MPa | ~ 10% | ~ 32 HRC |
| Aged (H900) | ~ 1240 MPa | ~ 1380 MPa | ~ 8% | ~ 44 HRC |
Key Characteristics and Applications of 1.4545 / Custom 450
High Strength and Toughness: Achieves high tensile and yield strength after aging while maintaining good toughness and ductility.
Good Corrosion Resistance: Offers corrosion resistance similar to Type 304 stainless steel in many environments, with improved resistance to stress corrosion cracking.
Precipitation Hardening: Can be machined in the solution-treated condition and then aged to high strength with minimal distortion.
Primary Applications:
Aerospace: Structural components, fasteners, landing gear parts, and engine mounts.
Marine: Propeller shafts, valves, and fittings in seawater environments.
Chemical Processing: Pump shafts, valve stems, and high-stress components in corrosive media.
Oil & Gas: Downhole tools, wellhead components, and high-pressure equipment.
What is the difference between Custom 450 (1.4545) and 17-4PH (1.4542)?
Custom 450 generally offers better toughness and ductility, especially in the transverse direction, due to its cleaner microstructure and balanced alloying. While both grades provide high strength and moderate corrosion resistance, Custom 450 is often chosen for applications requiring superior fracture toughness and resistance to stress corrosion cracking in chloride environments. 17-4PH may offer slightly higher hardness and wear resistance in some conditions.
What heat treatment is recommended for 1.4545 stainless steel?
For optimal properties, the material is typically solution treated at 1040°C followed by rapid cooling. It is then aged at temperatures between 480°C and 620°C, depending on the desired strength and toughness balance. Lower aging temperatures (e.g., 480°C for H900) yield higher strength and hardness, while higher temperatures (e.g., 620°C for H1150) provide better toughness and ductility. Pre-machining is usually performed in the solution-treated condition.
Looking for a Reliable Supplier of 1.4545 / Custom 450 Stainless Steel?
GNEE Steel supplies high-performance Custom 450 (1.4545) stainless steel in bar, plate, and forging forms, available in various heat-treated conditions to meet demanding aerospace, marine, 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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