Stainless Steel, Precipitation Hardening
2S143D (S143) Bar
Aerospace-grade precipitation hardening stainless steel.
S143 is a China aerospace grade. It is a precipitation hardenable stainless steel that offers moderate corrosion resistance and high mechanical strength. It is widely used in the aerospace and defense industries.
Material to S144 and S145 shares a common chemical composition with S143. Therefore material to S143 can be precipitation hardened using a different sequence of temperatures to produce material meeting the mechanical property requirements of S144 or S145.
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2S143D （S143） Related Specifications
| System / Standard | Country / Region | Grade / Designation |
| BS S100 (bar grade) | UK | 2S143 |
| BS S100 (bar grade) | UK | S143 / 2S143D (finally heat-treated bar) |
| UNS | International | S45000 |
| EN / W.Nr. | Europe | 1.4594 |
| EN Name (EN 10088) | Europe | X5CrNiMoCuNb14-5 |
| Trade name | International | FV520B |
| DEF STAN | UK | DEF STAN 95-14 (FV520B) |
| MSRR | UK / Aerospace | MSRR 6537 |
| GB (Chinese grade) | China | 0Cr14Ni5MoCuNb |
Properties
Chemical Composition
| Chemical Element | % Present |
| Carbon (C) | 0.00 - 0.07 |
| Chromium (Cr) | 13.20 - 14.70 |
| Nickel (Ni) | 5.00 - 5.80 |
| Manganese (Mn) | 0.00 - 1.00 |
| Phosphorous (P) | 0.00 - 0.04 |
| Sulphur (S) | 0.00 - 0.03 |
| Silicon (Si) | 0.00 - 0.60 |
| Niobium (Columbium) (Nb) | 0.10 - 0.40 |
| Molybdenum (Mo) | 1.20 - 2.00 |
| Copper (Cu) | 1.20 - 2.00 |
Mechanical Properties
| Mechanical Property | Value |
| Tensile Strength | 930-1180 MPa |
| Elongation A50 mm | 15 % |
| Hardness Brinell | 277-241 HB |
| Proof Stress | 780 MPa |
General Physical Properties
| Physical Property | Value |
| Density | 7.8 g/cm³ |
Applications of 2S143D / S143 Stainless Steel Bar
2S143D / S143 is a British Standard (BS) precipitation-hardening martensitic stainless steel.
It offers high strength, good toughness, moderate corrosion resistance, and excellent resistance to galling and wear.
Because it can be hardened by heat treatment, it is widely used in demanding mechanical and aerospace environments.
Main Applications
1. Aerospace Components
Landing gear parts
High-strength fasteners
Actuator components
Structural fittings
Turbine and compressor components
Linkages, brackets, and hinge assemblies
2. Defence and Military Equipment
Missile components
High-strength shafts and pins
Precision mechanical parts for vehicles and weapon systems
Components requiring both toughness and corrosion resistance
3. High-Performance Mechanical Engineering
High-load transmission parts
Wear-resistant mechanical shafts
Gears, spindles, and drive components
Pump and valve components operating under stress
Couplings and locking mechanisms
4. Energy & Power Equipment
High-strength components for gas turbines
Steam system parts
Fasteners and fittings operating at elevated temperatures
5. Industrial General Applications
Components requiring resistance to galling/seizing
High-strength bolts and studs
Tooling elements requiring both hardness and corrosion resistance
Precision machined parts
Characteristics of 2S143D / S143 Stainless Steel Bar
1. Precipitation-Hardening Martensitic Stainless Steel
2S143D / S143 is a Cu + Nb precipitation-hardening martensitic stainless steel, designed to achieve high mechanical strength through controlled aging.
2. High Strength After Aging Treatment
After solution treatment and double-stage aging, the alloy provides:
High tensile strength: approx. 930–1180 MPa
High yield strength: around 780 MPa
High hardness with excellent load-bearing capability
Suitable for highly stressed structural components.
3. Good Corrosion Resistance
Corrosion resistance is better than conventional martensitic grades (e.g., 420/440) and adequate for aerospace and mechanical applications, though slightly below that of Cr-rich PH grades like 17-4PH.
4. Excellent Galling and Wear Resistance
Owing to its alloying with Mo and Cu, S143 exhibits:
Outstanding anti-galling performance
Good resistance to wear and fretting corrosion
Stable surface performance under sliding contact
Ideal for components with repeated mechanical interaction.
5. Stable Mechanical Properties & Fatigue Performance
The alloy offers:
Stable microstructure after aging
Balanced toughness and strength
Reliable fatigue resistance under cyclic loading
Frequently selected for high-integrity aerospace parts.
6. Good Machinability in Bright Bar Condition (2S143D)
The suffix “D” indicates Bright Drawn Bar, providing:
High dimensional accuracy
Smooth surface finish
Good machinability for precision CNC operations
Suitable for tight-tolerance mechanical parts
7. Fully Magnetizable Material
As a martensitic PH stainless steel, S143 is magnetic, which may be relevant for applications involving sensors or magnetic systems.
8. Aerospace-Grade Reliability
S143 was developed for aerospace and defense use and provides:
High reliability
Consistent properties
Proven performance in critical flight hardware
One-Sentence Summary
S143 is a high-strength, precipitation-hardening martensitic stainless steel with excellent wear and galling resistance, good corrosion resistance, stable mechanical performance, and suitability for precision aerospace and high-load mechanical components.
Additional Information
Corrosion Resistance
S143 stainless steel provides useful corrosion resistance in mildly/moderate corrosion environments and is similar to that of basic 300 series stainless steels.
