ASTM A181 Gr 2
ASTM A181 Grade 2 Carbon Steel Forgings
ASTM A181 Gr 2 is a specification covering carbon steel forgings designed for high-temperature and high-pressure applications in industries such as oil & gas, power generation, and chemical processing. This grade provides higher tensile and yield strength compared to ASTM A181 Gr 1 and maintains good machinability, ductility, and weldability. It is widely used for manufacturing flanges, fittings, valves, and pressure-containing parts requiring reliable mechanical performance and structural integrity.
Key Features
Higher strength and toughness than A181 Gr 1
Excellent forgeability and machinability
Good ductility and impact resistance
Reliable weldability using conventional methods
Suitable for moderate temperature service conditions
Consistent grain structure for dimensional stability
ASTM A181 Gr 2 Specification
| Standard | Specification |
|---|---|
| Product Form | Forged flanges, fittings, valves, and components |
| Material Type | Carbon Steel |
| Grade | ASTM A181 Grade 2 |
| Manufacturing Process | Open die or closed die forging |
| Heat Treatment | Normalized or annealed as required |
| Service Temperature | Ambient to moderately elevated temperatures |
ASTM A181 Gr 2 Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM / ASME | A181 Gr 2 / SA181 Gr 2 |
| EN | C35E (1.1181) |
| DIN | C35 |
| BS | 1501-161-430A |
Available Sizes
| Form | Size Range |
|---|---|
| Forged Flanges | ½” to 24” NB |
| Forged Fittings | ½” to 4” NB |
| Custom Forged Components | As per client specifications |
Chemical Composition
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.25 – 0.35 |
| Manganese (Mn) | 0.60 – 1.00 |
| Phosphorus (P) | 0.035 max |
| Sulphur (S) | 0.040 max |
| Silicon (Si) | 0.10 – 0.35 |
Mechanical Properties
| Property | Unit | Value |
|---|---|---|
| Tensile Strength | MPa | 485 min |
| Yield Strength | MPa | 250 min |
| Elongation | % | 20 min |
| Reduction of Area | % | 35 min (approx.) |
| Hardness | HB | 170 – 197 |
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 2 Forged Flanges
Corrosion Resistance
ASTM A181 Gr 2 provides moderate resistance to atmospheric and mild chemical corrosion. It is suitable for environments where corrosion is not severe. For improved protection, surface coatings such as galvanizing, painting, or plating can be applied. It is not recommended for use in highly corrosive or marine environments.
Heat Resistance
This grade maintains good mechanical properties at temperatures up to 400°C. Beyond this range, strength and toughness may decrease. It performs well in applications involving cyclic thermal loading and moderate heat exposure.
Heat Treatment
Normalizing: 890°C – 950°C followed by air cooling.
Annealing: 850°C – 900°C followed by slow furnace cooling.
These treatments enhance toughness, machinability, and dimensional accuracy.
Welding
ASTM A181 Grade 2 can be welded using all conventional processes, including SMAW, GMAW, and GTAW. Preheating is recommended for thicker sections to prevent cracking. Post-weld heat treatment (PWHT) may be applied to relieve internal stresses and improve mechanical properties.
Fabrication
Excellent forgeability and machinability make this grade easy to shape and machine. Forging is typically performed between 900°C and 1200°C, followed by normalizing or annealing. It can be readily formed and machined to precise tolerances for various industrial applications.
Applications
Pressure vessel components
Industrial valves and flanges
Pipe fittings and connectors
Power generation and petrochemical equipment
Pumps, shafts, and mechanical parts
Oil & gas transmission systems