Key Feature

The Stabilized Ferritic Stainless Steel Pipe for Weld Fabrication. Aluminum addition prevents martensite formation in welds, providing consistent properties in as-welded condition without post-weld heat treatment.

Specifically designed for welded piping assemblies where 430 would harden excessively in heat-affected zones.

Common Designations

UNS S40500
AISI 405
ASTM A268 TP405 (Seamless Ferritic/Martensitic Pipe)
EN 1.4002, X6CrAl13
JIS SUS405
BS 405S17

One of the few ferritic stainless steels specifically engineered for weldability in piping applications.

Chemical Composition (Typical wt.%)

C: ≤ 0.08
Cr: 11.5 - 14.5
Al: 0.10 - 0.30Mn: ≤ 1.00
Si: ≤ 1.00
P: ≤ 0.040
S: ≤ 0.030

Aluminum content is critical for ferrite stabilization and preventing martensite formation in welded piping.

Mechanical Properties (Annealed)

Tensile Strength: ≥ 415 MPa
Yield Strength: ≥ 205 MPa
Elongation: ≥ 20%
Hardness: ≤ 183 HB

Moderate strength with good ductility; comparable to 430 in annealed condition.

Weld Zone Properties

HAZ Hardness: Typically ≤ 250 HB
No Martensite FormationConsistent Properties across weldment
No Post-Weld Heat Treatment required

Aluminum promotes ferrite formation, preventing hard, brittle zones in pipe welds.

Physical Properties

Density: 7.70 g/cm³
Melting Range: 1480 - 1530 °C
Thermal Expansion: 10.8 × 10⁻⁶/K (20-400°C)
Thermal Conductivity: 25.0 W/m·K (100°C)
Strongly magnetic

Typical ferritic stainless steel properties with lower thermal expansion than austenitic grades.

Corrosion Resistance

Good resistance to atmospheric corrosion, nitric acid, organic acids, and fresh water. Similar to 410 but inferior to 304. Not suitable for marine or chloride-rich environments.

Adequate for many industrial piping applications; not for severe corrosive conditions.

Welding Characteristics

Good weldability for ferritic grade
Aluminum stabilization maintains properties
No pre-heat required for thin sections
Matching filler metals recommended

Better weldability than standard ferritic grades due to aluminum stabilization.

Pressure Ratings

Schedule 10/40: Standard piping applications
ASME B31.3 compliant for specific services
Limited to moderate pressures

Suitable for low to moderate pressure applications in appropriate environments.

Temperature Limits

Maximum Service: 700°C
Continuous Service: Up to 650°C
Avoid: 475-900°C (embrittlement range)
Not for cryogenic applications

Limited high-temperature capability due to 475°C embrittlement risk.

Key Standards

ASTM A268 TP405: Seamless Ferritic Pipe
ASTM A791: Welded Ferritic Pipe
AMS 5507 (Aerospace)
EN 10216-5: Seamless Pressure Tubes
JIS G3463: Stainless Steel Pipe

Widely specified in heat exchanger and welded fabrication applications.

Common Applications

• Heat Exchanger Piping: Tube sheets, baffles, headers, support systems
• Furnace Piping: Radiant tubes, burner piping, structural supports
• Chemical Processing: Welded tanks, reactors, mild service piping
• Power Generation: Boiler parts, feedwater heaters, condenser components
• Automotive: Exhaust system components, manifolds
• Food Processing: Welded equipment frames, supports, mild service piping
• Industrial: Ventilation ducting, fume exhaust stacks (mild conditions)

Specifically selected where welding is extensive and consistent weld zone properties are critical in piping.