ASTM A181 Gr 1
ASTM A181 Grade 1 Carbon Steel Forgings
ASTM A181 Grade 1 is a standard specification covering carbon steel forgings used for general-purpose industrial applications at ambient to moderately elevated temperatures. This material is commonly utilized in manufacturing flanges, fittings, valves, and other pressure-containing components. ASTM A181 Gr 1 offers good machinability, moderate strength, and excellent weldability, making it suitable for applications where toughness and ease of fabrication are essential.
Key Features
Excellent weldability and formability
Moderate tensile and yield strength suitable for general-purpose use
Good machinability for precision forging and shaping
Ideal for ambient to moderately high temperature service
Consistent dimensional stability and surface finish
Specification
| Standard | Specification |
|---|---|
| Product Form | Forged flanges, fittings, valves, and similar components |
| Material Type | Carbon Steel |
| Grade | ASTM A181 Grade 1 |
| Manufacturing Process | Open die or closed die forging |
| Heat Treatment | Normalized or annealed as required |
| Application Temperature | Ambient to moderate temperature service |
ASTM A181 Gr 1 Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM / ASME | A181 Gr 1 / SA181 Gr 1 |
| EN | C22E (1.1151) |
| DIN | C22 |
| BS | 1501-161-400A |
Available Sizes
| Form | Size Range |
|---|---|
| Forged Flanges | ½” to 24” NB |
| Forged Fittings | ½” to 4” NB |
| Custom Forged Components | As per customer requirements |
ASTM A181 Gr 1 Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.15 – 0.30 |
| Manganese (Mn) | 0.60 – 1.00 |
| Phosphorus (P) | 0.035 max |
| Sulphur (S) | 0.040 max |
| Silicon (Si) | 0.10 – 0.35 |
ASTM A181 Gr 1 Mechanical Properties
| Property | Unit | Value |
|---|---|---|
| Tensile Strength | MPa | 415 min |
| Yield Strength | MPa | 205 min |
| Elongation | % | 22 min |
| Reduction of Area | % | 35 min (approx.) |
| Hardness | HB | 143 – 187 |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1425 – 1540°C |
| Modulus of Elasticity | 200 GPa |
| Thermal Conductivity | 51 W/m·K |
| Electrical Resistivity | 0.1 µΩ·m |
Type of ASTM A181 Gr 1 Forged Flanges
Types
Forged Flanges (Weld Neck, Slip-On, Blind, Socket Weld, Threaded)
Forged Fittings (Elbows, Tees, Couplings, Reducers, Caps)
Custom Machined Forged Components
Corrosion Resistance
ASTM A181 Gr 1 exhibits fair resistance to atmospheric corrosion and mild chemical environments. For enhanced protection in corrosive media, surface coatings, galvanizing, or painting are recommended. The material is not intended for highly corrosive or marine applications.
Heat Resistance
ASTM A181 Grade 1 performs effectively at moderate temperatures. Prolonged exposure above 400°C is not recommended as it may reduce mechanical strength. It maintains dimensional stability and toughness under normal service conditions.
Heat Treatment
Annealing: 870°C – 900°C followed by slow cooling.
Normalizing: 890°C – 950°C followed by air cooling.
These processes refine the grain structure and enhance ductility and machinability.
Welding
ASTM A181 Gr 1 can be readily welded using standard methods such as SMAW, GTAW, or GMAW. Preheating is not usually required, but post-weld stress relieving may be performed to reduce residual stresses for critical components.
Fabrication
The material offers excellent forgeability and machinability, allowing easy shaping and finishing. Hot forging is performed between 900°C and 1200°C, followed by suitable heat treatment to restore mechanical properties.
Applications
General engineering components
Industrial valves and flanges
Forged pipe fittings
Pumps and pressure vessels
Power generation and petrochemical industries
Heat exchangers and mechanical assemblies