What is the difference between A36 and A516 gr 70

A36 vs. A516 Gr 70: A Detailed Comparison for Industrial Applications

When choosing steel plates for construction or industrial projects, ASTM A36 and ASTM A516 Gr 70 are two commonly considered materials. While both are carbon steels, they serve distinct purposes due to differences in their composition, properties, and applications. At Gangsteel, we supply high-quality A516 Gr 70 steel plate for pressure vessel applications and other standards like ASTM A285 and ASTM A537. This article breaks down the key differences between A36 and ASTM A516 Gr 70 plate to help you decide which is best for your project, focusing on pressure vessel steel plate Grade 70 and related standards.

1. What is A36 and A516 Gr 70 steel plate

ASTM A36 steel plate

ASTM A36 is a general-purpose carbon steel used primarily for structural applications, such as buildings, bridges, and machinery. It’s known for its versatility, affordability, and ease of welding, making it a go-to choice for non-pressure applications. A36 is specified under the ASTM A36/A36M standard and is not typically designed for high-pressure or low-temperature environments.

ASTM A516 Gr 70 steel sheet

ASTM A516 Gr 70 is a carbon steel plate specifically designed for pressure vessels and boilers operating at moderate and low temperatures. Part of the ASTM A516 standard, it offers high strength and toughness, with optional NACE MR0175 and HIC (Hydrogen Induced Cracking) compliance for boiler quality steel plate for oil and gas applications in sour gas environments.

Key Difference: A36 is a structural steel for general use, while A516-70 carbon steel plate is engineered for pressure vessels, offering superior performance under pressure and in corrosive conditions.

2. Chemical Composition Comparison

The chemical makeup of each steel impacts its strength, weldability, and suitability for specific environments.

ASTM A36 Chemical Composition

• Carbon (C): ≤ 0.25% (for plates ≤ 3/4 inch), ≤ 0.26% (> 3/4 inch)
• Silicon (Si): ≤ 0.40%
• Manganese (Mn): 0.80-1.20% (varies by thickness)
• Phosphorus (P): ≤ 0.04%
• Sulfur (S): ≤ 0.05%
• Copper (Cu): ≥ 0.20% (when specified)

ASTM A516 Gr 70 Chemical Composition

• Carbon (C): ≤ 0.27% (<12.5mm), ≤ 0.28% (12.5-50mm), ≤ 0.30% (50-100mm), ≤ 0.31% (100-200mm), ≤ 0.31% (>200mm)
• Silicon (Si): 0.15-0.40%
• Manganese (Mn): 0.85-1.20%
• Phosphorus (P): ≤ 0.035%
• Sulfur (S): ≤ 0.035%

Key Differences:

• Carbon Content: A516 Gr 70 chemical composition has slightly higher carbon limits for thicker plates, enhancing strength but requiring more welding care compared to A36.
• Sulfur and Phosphorus: A516 Gr 70 has tighter limits (≤ 0.035% vs. A36’s ≤ 0.05% and ≤ 0.04%), improving weldability and performance in pressure vessel steel plate for petrochemical applications.
• Copper: A36 may include copper for corrosion resistance, while A516 Gr 70 typically does not, focusing instead on pressure vessel performance.

Carbon Equivalent (Ceq): A516 Gr 70 (Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 %) has a higher Ceq due to its composition, which may require preheating during welding compared to A36.

3. Mechanical Properties Comparison

The mechanical properties determine how each steel performs under stress.

Key Differences:

• Strength: pressure vessel steel plate Grade 70 has higher yield (260 MPa) and tensile strength (485-620 MPa) than A36 (250 MPa, 400-550 MPa), making it better for high-pressure applications.
• Elongation: A36 offers slightly better ductility (23% in 50mm), while A516 Gr 70 plate prioritizes strength over flexibility.
• Impact Resistance: a516 gr 70 impact test results show superior toughness at low temperatures, unlike A36, which is not typically tested for impact in structural applications.

4. Weldability and Fabrication

Both steels are weldable, but their applications influence welding considerations:

• A36: Excellent weldability due to lower carbon content and fewer alloying elements. It’s commonly welded using SMAW, GMAW, or GTAW with fillers like AWS A5.1 E7018. No preheating is typically needed for thinner sections.
• A516 Gr 70: Also weldable, but its higher carbon and manganese content may require preheating (100-150°C) and post-weld heat treatment for thicker plates, especially in A516 GR 70 Material specification applications. Recommended fillers include E7018 or ER70S-6.

Key Difference: A36 is easier to weld for general structural work, while A516-70 carbon steel plate requires more care in pressure vessel fabrication due to its higher strength and potential for cracking in sour gas environments.

5. Applications

ASTM A36 Applications

• Structural Components: Beams, columns, and plates for buildings, bridges, and machinery.
• General Fabrication: Used in non-pressure applications like platforms, frames, and supports.
• Construction: Ideal for projects not requiring high pressure or low-temperature resistance, similar to ASTM A285 or ASME SA285.

ASTM A516 Gr 70 Applications

• Pressure Vessels: High-pressure vessels for oil and gas, petrochemical, and power generation industries.
• Boilers: Steam drums and boiler components, comparable to JIS G3103.
• Storage Tanks: Tanks for liquefied gases or chemicals, aligning with ASTM A537 or EN 10028-2.
• Offshore Platforms: Structures in corrosive marine environments, similar to ASTM A203.

Key Difference: A36 is suited for structural and non-pressure applications, while ASTM A516 Gr 70 plate is designed for high-pressure, low-temperature, and sour gas environments in boiler quality steel plate for oil and gas.

6. Equivalent Grades

Key Difference: ASTM A516 GR70 equivalent material, like P355GH or EN 10028-3, is tailored for pressure vessels, while A36 equivalents like S275 or JIS G3103 are for structural use.

7. NACE and HIC Compliance

• A36: Not typically supplied with NACE or HIC compliance, as it’s not designed for sour gas environments.
• A516 Gr 70: Can be provided with NACE MR0175 and HIC testing, ensuring resistance to Hydrogen Induced Cracking in pressure vessel steel plate for petrochemical applications. Supplementary tests (Z15, Z25, Z35, S1-S9, S11, S12, S14, S17) align with ASTM A516.

Key Difference: a516 gr 70 equivalent is optimized for corrosive environments, unlike A36.

8. Dimensions and Availability

• A36: Typically available in thicknesses from 3mm to 200mm, with standard structural sizes (e.g., 1200-2500mm width, up to 12000mm length).
• A516 Gr 70: Available in thicknesses from 6mm to 300mm, widths 1500-4050mm, and lengths 3000-15000mm, per A516 GR 70 Plate thickness.

Key Difference: A516 Gr 70 offers a broader thickness range for heavy-duty pressure vessels, while A36 is more common in thinner structural plates.

9. Cost and Availability

• A36: Generally cheaper and more widely available due to its use in general construction, competing with standards like ASTM A514.
• A516 Gr 70: More expensive due to its specialized pressure vessel properties and testing requirements, similar to ASTM A517 or ASTM A662.

10. Why Choose Gangsteel?

Gangsteel is a trusted ASTM A516 GR 70 NACE HIC steel plate supplier, offering:

• Quality: Rigorous testing for A516 Gr 70 chemical composition and HIC/NACE compliance.
• Global Delivery: Efficient logistics for ASTM A516, ASTM A387, and ASTM A225.
• Customization: Tailored sizes for pressure vessel steel plate Grade 70.
• Support: Guidance to choose between A36, A516 Gr 70, or alternatives like ASME SA353.

11. Conclusion

ASTM A36 is ideal for structural applications where cost and ease of fabrication are priorities, while ASTM A516 Gr 70 excels in high-pressure, low-temperature, and corrosive environments, such as boiler quality steel plate for oil and gas. For pressure vessels, ASTM A516 Gr 70 plate is the clear choice due to its strength and specialized testing. Contact Gangsteel or visit our product page for quotes and support on A516 Gr 70 or related standards like EN 10028-6.