ASTM A105 material is a type of forged carbon steel used for manufacturing high-strength flanges, forged fittings, and valves, widely applied in industrial pressure piping systems.
Because of its advantages of high strength, good toughness, excellent weldability, and moderate price, A105 is the preferred material for carbon steel flanges in ASME piping systems.
What is ASTM A105 Material?
ASTM A105 material is a forged carbon steel standard established by ASTM (American Society for Testing and Materials). It is mainly used to manufacture forgings for piping systems operating at ambient and high temperatures. This includes ASME B16.5 pipe flanges, ASME B16.11 forged fittings, ASME B16.34 valve parts, and various pressure components.
Chemical Composition
NOTE 1 — For each reduction of 0.01% below the specified carbon maximum (0.35%), an increase of 0.06% manganese above the specified maximum (1.05%) will be permitted up to a maximum of 1.65%.
| Element | Composition, % |
| Carbon | 0.35 max |
| Manganese | 0.60–1.05 |
| Phosphorus | 0.035 max |
| Sulfur | 0.040 max |
| Silicon | 0.10–0.35 |
| Copper | 0.40 max【A】 |
| Nickel | 0.40 max |
| Chromium | 0.30 max【A.B】 |
| Molybdenum | 0.12 max【A.B】 |
| Vanadium | 0.08 max【A】 |
【A】The sum of copper, nickel, chromium, molybdenum, and vanadium shall not exceed 1.00%.
【B】The sum of chromium and molybdenum shall not exceed 0.32%.
Mechanical Properties
| Property | Requirement |
| Tensile strength, min, ksi [MPa]【B】 | 70 [485] |
| Yield strength, min, ksi [MPa] | 36 [250] |
| Elongation in 2 in. or 50 mm, minimum % (standard round specimen) | 22 |
| Strip specimens (wall thickness ≥ 5/16 in. [7.94 mm]) and small full-section specimens | 30 |
| Formula for calculating minimum elongation for strip specimens thinner than 5/16 in. [7.94 mm]: t = actual thickness | Inch-pound units: 48t + 15 SI units: 1.9t + 15 |
| Reduction of area, min, %【C】 | 30 |
| Hardness, HBW, max | 197 |
【A】For small forgings, see 8.3.4.
【B】Determined by either the 0.2% offset method or the 0.5% extension-under-load method.
【C】For round specimens only.
A105 is commonly supplied in the Normalized or Normalized + Tempered (N+T) condition to improve toughness and stability.
Difference Between ASTM A105 and A105N
A105N is simply the Normalized version of A105.
Normalization is not mandatory for A105.
Normalization improves:
- Uniform microstructure
- Better toughness
- Stronger resistance to brittle fracture
- Better suitability for lower-temperature service
- Easier compliance with NACE MR0175 hardness requirements
- More stable ultrasonic inspection results
Therefore, A105N is required for some stricter service conditions.
Benefits and Limitations
A105 exhibits a minimum tensile strength of 485 MPa and a minimum yield strength of 250 MPa, providing adequate pressure-containing capability for the majority of industrial piping systems and flanged connections. The material features a refined forged microstructure with minimal internal discontinuities, resulting in high service reliability. With a moderate carbon content, A105 generally does not require complex preheat procedures during welding, making it suitable for field installation, piping modification, and routine fabrication work.
A105 is applicable for operating temperatures ranging from ambient to elevated conditions (-29°C to 425°C), and it is commonly used in systems handling steam, hydrocarbons, and various chemical media. As one of the most widely used forged carbon steels, it offers a significantly lower cost compared with stainless steels and alloy steels, and is readily available from global stock.
ASTM A105 is not recommended for low-temperature applications (below -29°C), and its mechanical performance degrades when service temperatures exceed 425°C. The material is also unsuitable for sour-service conditions unless hardness is strictly controlled. When not supplied in the normalized and tempered condition, A105 may fail to meet NACE requirements.
Due to its carbon-steel nature, the alloy has limited corrosion resistance and is susceptible to rusting; therefore, protective coatings such as FBE, PTFE, galvanizing, or painting are necessary, or stainless steel should be selected when corrosion resistance is critical.
ASTM A105 Equivalent Materials
According to different temperature, impact requirements, and standard systems, common equivalent materials for ASTM A105 include:
| Standard | Equivalent Grade | Notes |
| ASME / ASTM | A105 | Original standard |
| EN (Europe) | C22.8 / 1.0460 | Most common European equivalent |
| DIN (Germany) | C22.8 | Same as EN, for forgings |
| ISO | C22 / C22E | General carbon steel forging grade |
| JIS (Japan) | SF440A | Closely matches A105 |
| GB (China) | 20# (forged) or 20 steel forgings | Similar chemical composition and properties |
| BS (UK) | 080M15 / 150M19 | Range of low-carbon forging steels |
| UNI (Italy) | C22 Fe360 | Similar to C22.8 |
Strictly speaking, in the field of “forged carbon steel pressure components,” the true equivalent of A105 is EN 10222-2 — C22.8 (1.0460), which is widely accepted internationally as the closest and directly interchangeable material.
Conclusion
ASTM A105 remains one of the most widely used forged carbon steel materials for flanges, fittings, and pressure components in industrial piping systems. Its excellent mechanical strength, good weldability, and cost-effectiveness make it suitable for a wide range of applications from ambient to high-temperature conditions.
Although it has limitations in low-temperature and sour environments, proper heat treatment—especially normalization—significantly enhances its performance and reliability. When international standards are involved, EN 10222-2 C22.8 (1.0460) is considered the closest equivalent to ASTM A105, offering engineers a reliable alternative across global projects.
