Key Feature

The Steam-Turbine Martensitic Stainless Steel Bar Stock. Optimized chemistry for high-temperature strength, oxidation resistance, and reliable performance in steam and elevated temperature services.

The traditional material choice for steam turbine components and critical power generation bar applications.

Common Designations

UNS S40300
AISI 403
ASTM A276 (Stainless Steel Bars)
EN 1.4000, X6Cr13
JIS SUS403
AMS 5614 (Aerospace)

ASTM A276 is the primary specification for general bar applications.

Chemical Composition (Typical wt.%)

C: 0.08 - 0.15
Cr: 11.5 - 13.0
Mn: ≤ 1.00
Si: 0.15 - 0.35P: ≤ 0.040
S: ≤ 0.030

Lower silicon than 410 (0.15-0.35% vs ≤1.00%) improves high-temperature properties and reduces scaling.

Mechanical Properties (Annealed)

Tensile Strength: ≥ 480 MPa
Yield Strength: ≥ 275 MPa
Elongation: ≥ 20%
Hardness: ≤ 217 HB
Machinability: 50% of B1112 steel

Moderate properties in annealed condition; designed for enhancement through heat treatment.

Mechanical Properties (Hardened & Tempered)

Tensile Strength: Up to 1300 MPa
Yield Strength: Up to 1100 MPa
Hardness: Up to 42 HRC
Elongation: 10-15%
Impact Toughness: Good

High strength achievable through proper heat treatment; suitable for dynamic loading in bar applications.

Elevated Temperature Properties

Continuous Service: Up to 700°C
Intermittent Service: Up to 750°C
Creep Strength: Good up to 600°C
Oxidation Resistance: Good up to 650°C

Specifically designed for steam turbine applications (typically 300-600°C).

Physical Properties

Density: 7.70 g/cm³
Melting Range: 1480 - 1530 °C
Thermal Expansion: 10.8 × 10⁻⁶/K (20-400°C)
Thermal Conductivity: 24.9 W/m·K (100°C)
Strongly magnetic

Lower thermal expansion than austenitic grades; beneficial for thermal cycling applications.

Available Forms

Rounds: 6mm - 250mm diameter
Squares: 6mm - 125mm
Hexagons: 6mm - 100mm
Flats: Various sizes
Billets: For forging applications
Forgings: Custom forged components

Available in sizes suitable for turbine and power generation components.

Surface Conditions

Hot Rolled: Black, scaled surface
Cold Drawn: Bright, smooth finish
Centerless Ground: Precision ground
Polished: For specific applications
Peeled: Improved surface for machining

Various surface finishes for different application requirements.

Corrosion Resistance

Moderate resistance to atmospheric corrosion, steam, and mild chemicals. Better than carbon steels but inferior to austenitic stainless steels.

Suitable for steam, condensate, and mildly corrosive elevated temperature environments.

Machining Characteristics

• Best machined in annealed condition• Heat treat after machining• Moderate tool wear• Good chip control• Surface finish generally good

Typically machined in soft condition, then heat treated to final hardness.

Heat Treatment Capability

Austenitizing: 980-1010°C (air or oil quench)
Tempering Range: 550-650°C (for turbine applications)
Annealing: 815-870°C, slow cool
Stress Relief: 650-760°C

Typically tempered at higher temperatures than 410 for improved toughness.

Key Standards

ASTM A276 403: Stainless Steel Bars
ASTM A479 403: Bars for Pressure Vessels
ASTM A484: General Requirements
EN 10088-3: Stainless Steel Bars
JIS G4303: Stainless Steel Bars
ASME SA479: Code Construction

Available in various hardness conditions: annealed, hardened & tempered.

Common Applications

• Steam Turbine Components: Blades, buckets, rotor parts, seals, fasteners
• Power Generation: Valve stems, pump shafts, turbine fasteners, structural components
• Aerospace: Compressor blades, engine components, high-temperature fasteners
• Industrial Equipment: High-temperature pump shafts, valve components, wear parts
• Oil & Gas: Wellhead components, valve trim (non-corrosive services)
• Fastener Systems: High-temperature bolts, studs, nuts for steam service
• Tooling: Jigs, fixtures, molds for elevated temperature use

Specifically developed for and primarily used in steam turbine and high-temperature bar applications.