CUSTOM 455 (UNS S45500): An Age Hardenable, Martensitic Stainless Steel
Alloy Definition and Chemical Composition
CUSTOM 455 is an age hardenable stainless steel grade with a martensitic structural characteristic. Offering properties such as high strength, good toughness and excellent corrosion resistance together, this alloy finds a broad area of use especially in the aerospace, defence and chemical processing sectors.
Especially with the Solution Annealing + Aging operations, its hardness and strength can be raised to high levels. The martensite and intermetallic precipitates (especially Cu-rich phases) formed at a rate of 10–12% by the ageing operation provide the high mechanical values of this alloy.
Its typical chemical composition (% by weight):
- Chromium (Cr): 11.0 – 12.5%
- Nickel (Ni): 7.5 – 9.5%
- Copper (Cu): 1.5 – 2.5%
- Titanium (Ti): 0.80 – 1.40%
- Carbon (C): 0.05% max
- Molybdenum (Mo): 0.50% max
- Iron (Fe): Balance
The copper and titanium ratio in the alloy is of critical importance for the age hardening mechanism. The low carbon content, on the other hand, limits carbide precipitation at the grain boundaries and reduces the risk of cracking after welding.
CUSTOM 455 Standards and Specifications
CUSTOM 455 is defined in the following industry standards:
- ASTM A564 – General standard for age hardenable stainless steels
- AMS 5617 – Bar, wire, forged and formed products
- AMS 5860 – Plate and sheet products
- UNS S45500 – Unified Numbering System designation
In addition, in some applications it is also compliant with corrosion resistance related standards such as NACE MR0175/ISO 15156. These standards are of importance for service especially in environments containing hydrogen sulphide (H₂S).
CUSTOM 455 Trade Names and Equivalent Alloys
- Custom 455® – Registered brand of Carpenter Technology
- 455 Stainless Steel
- UNS S45500
This alloy is generally compared with 17-4 PH. However, Custom 455 provides higher tensile and yield strength than 17-4 PH while preserving similar corrosion resistance. In addition, 455 offers better weldability and heat treatment stability.
CUSTOM 455 Mechanical and Physical Properties
CUSTOM 455 offers a broad range of mechanical performance depending on the age hardening operation. These values can be adjusted by heat treatment according to the needs of the application.
Typical values after solution annealing + H900 ageing:
- Tensile strength (UTS): 1310–1380 MPa
- Yield strength (0.2%): 1170–1240 MPa
- Elongation (%): 10–12
- Hardness (Rockwell C): RC 44–47
- Density: 7.78 g/cm³
- Modulus of Elasticity: ~200 GPa
- Melting Range: 1370–1410 °C
Corrosion resistance is equivalent to that of 304 type stainless steel, and it performs well in most atmospheric, chemical and marine environments.
Application Areas
CUSTOM 455 is preferred in many sectors where the combination of high strength with a stainless character is required:
1.Aerospace
#Propeller shafts, fasteners, landing gear parts
2.Defence and Military Systems
#Rocket connection equipment, radar fasteners
3.Petrochemicals
#Pressure valves, gasket and flange systems
4.Medical Equipment
#Orthopaedic implants, surgical instruments
5.Food Processing and Beverage Industry
#Corrosion resistant shafts, pumps
6.Nuclear Energy
#Durable fittings used in reactor systems
Advantages
- Age Hardenability:High strength levels can be obtained with simple heat treatments.
- High Corrosion Resistance: It is resistant to general atmospheric corrosion, including in chlorinated environments.
- Mechanical Strength: Tensile strength above 1300 MPa is obtained with heat treatments such as H900 or H1000.
- Weldability: It offers better welding performance than other martensitic stainless steels.
- Dimensional Stability: The tendency to shape distortion and cracking after ageing is low.
Disadvantages
- Drop in Toughness at Low Temperature: Impact toughness is limited at very low temperatures.
- Machining Difficulties: Its machinability in the hardened condition is poor, and cutting tool wear is rapid.
- Controlled Heat Treatment Requirement: The ageing operation in particular requires precise duration and temperature control.
- Cost: It is more expensive than standard ferritic or austenitic stainless steels.
Conclusion and Engineering Evaluation
CUSTOM 455 is a versatile material from an engineering point of view, bringing together mechanical strength, corrosion resistance and dimensional stability. It meets the need for a stainless steel that is both durable and machinable, especially in fields such as the aerospace, defence and chemical process industry.
Together with its age hardenability and good weldability, it offers a solution for a large number of engineering problems thanks to flexible, application-specific heat treatment options. However, because of its high performance, its machining and purchasing costs are relatively high.
#ASTMA564
#AMS5617
#AMS5860
#UNSS45500
#Custom455®
#455Stainless Steel
#UNSS45500
We supply this material
We supply Custom 455 — to AMS 5617, AMS 5860 standards, in the dimensions and forms required. Contact us for stock availability and pricing.
Similar products
13-8 PH · 15-5 PH · 17-4 PH · 17-7 PH · Precipitation hardening steels →