How Does ASTM A516 Gr 70 Differ from Grade 65 or 60?

ASTM A516 Gr 70 Differ from Grade 65 or 60 Steel Plate

When selecting carbon steel plates for pressure vessels and boilers, ASTM A516 Grade 70, Grade 65, and Grade 60 are among the most commonly considered options due to their suitability for moderate and low-temperature services. At Gangsteel, we specialize in supplying high-quality ASTM A516 Grade 70 steel plate alongside other grades like ASTM A285, ASTM A537, and ASTM A515. This article provides a detailed comparison of A516 Gr 70 steel plate with Grades 65 and 60, focusing on their chemical composition, mechanical properties, applications, and suitability for pressure vessel steel plate Grade 70 applications, including NACE and HIC compliance.

1. What is steel plate of ASTM A516 Grades

The ASTM A516 specification, accessible via ASTM A516, covers carbon steel plates for pressure vessels in moderate and low-temperature environments. The grades—60, 65, and 70—differ primarily in strength, with A516-70 carbon steel plate offering the highest strength, followed by Grade 65 and Grade 60. All three grades can be supplied with NACE MR0175/ISO 15156 and HIC (Hydrogen Induced Cracking) compliance, making them suitable for A516 GR 70 Material specification in sour gas environments. Plates up to 40mm are typically as-rolled, while those over 40mm are normalized.

2. Chemical Composition Comparison

The chemical composition of A516 Gr 70 chemical composition compared to Grades 65 and 60 influences their strength and weldability.

ASTM A516 Grade 60

• Carbon (C): ≤ 0.21% (<12.5mm), ≤ 0.23% (12.5-50mm), ≤ 0.25% (50-100mm), ≤ 0.27% (100-200mm), ≤ 0.27% (>200mm)
• Silicon (Si): 0.15-0.40%
• Manganese (Mn): 0.60-1.20%
• Phosphorus (P): ≤ 0.035%
• Sulfur (S): ≤ 0.035%

ASTM A516 Grade 65

• Carbon (C): ≤ 0.24% (<12.5mm), ≤ 0.26% (12.5-50mm), ≤ 0.28% (50-100mm), ≤ 0.29% (100-200mm), ≤ 0.29% (>200mm)
• Silicon (Si): 0.15-0.40%
• Manganese (Mn): 0.85-1.20%
• Phosphorus (P): ≤ 0.035%
• Sulfur (S): ≤ 0.035%

ASTM A516 Grade 70

• 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 the highest carbon content, followed by Grade 65 and Grade 60, contributing to its superior strength but slightly reduced weldability.
• Manganese: Grades 65 and 70 have higher manganese content (0.85-1.20%) than Grade 60 (0.60-1.20%), enhancing strength.
• Carbon Equivalent (Ceq): Calculated as C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 %, Gr 70 has a higher Ceq, requiring more welding precautions compared to Grades 65 and 60.

3. Mechanical Properties Comparison

The mechanical properties of ASTM A516 Gr 70 plate compared to Grades 65 and 60 are critical for determining their suitability.

Key Differences:

• Strength: pressure vessel steel plate Grade 70 offers the highest yield (260 MPa) and tensile strength (485-620 MPa), followed by Grade 65 (240 MPa, 450-585 MPa) and Grade 60 (220 MPa, 415-550 MPa).
• Elongation: Grade 60 has the highest elongation (up to 23%), indicating better ductility, while A516 Gr 70 plate has slightly lower elongation (17-21%), prioritizing strength.
• Impact Resistance: a516 gr 70 impact test results show excellent toughness, comparable to Grades 65 and 60, with all grades suitable for low-temperature applications.

4. Weldability and Fabrication

All three grades are weldable due to low carbon content, but differences exist:

• A516 Gr 60: Best weldability due to lowest carbon content, ideal for complex fabrications in pressure vessel steel plate for oil and gas.
• A516 Gr 65: Good weldability, with slightly higher carbon requiring minimal preheating for thicker plates.
• A516 Gr 70: Good weldability, but higher carbon and Ceq may require preheating (100-150°C) and post-weld heat treatment for thicker sections, as seen in A516-70 carbon steel plate.

Filler Metals: AWS A5.1 E7018 or AWS A5.5 E7016-1 for SMAW; ER70S-6 for GMAW, applicable to all grades but with stricter controls for A516 Gr 70 plate.

5. Equivalent Material Grades

Each grade aligns with international standards, ensuring versatility:

Key Differences: ASTM A516 GR70 equivalent material, such as P355GH, reflects its higher strength compared to a516 gr 70 equivalent for Grades 65 and 60, which align with lower-strength standards.

6. Applications

The choice of grade depends on project requirements:

• A516 Gr 60: Used in pipelines, storage tanks, and pressure vessels with moderate strength needs, ideal for ASTM A285 or ASME SA285 applications.
• A516 Gr 65: Suitable for boilers and reactors requiring balanced strength and weldability, comparable to JIS G3115.
• A516 Gr 70: Preferred for high-pressure vessels, boilers, and offshore platforms in pressure vessel steel plate Grade 70 applications, similar to ASTM A537 or EN 10028-2.

7. NACE and HIC Compliance

All grades can be supplied with NACE MR0175 and HIC compliance, tested via:

• HIC Testing: Ensures resistance to Hydrogen Induced Cracking in sour gas environments.
• Supplementary Tests: Z15, Z25, Z35, S1-S9, S11, S12, S14, S17, as per ASTM A516.

Key Difference: A516 Gr 70 impact test results support its use in more severe sour gas environments compared to Grades 65 and 60.

8. Dimensional Specifications

All grades share similar dimensions:

• Thickness: 6mm to 300mm (see A516 GR 70 Plate thickness)
• Width: 1500mm to 4050mm
• Length: 3000mm to 15000mm

Tolerances comply with ASTM A20/A20M, with A516 Gr 70 plate offering precision for high-pressure applications.

9. Comparison Summary

• Strength: ASTM A516 Grade 70 steel plate > Grade 65 > Grade 60.
• Weldability: Grade 60 > Grade 65 > A516-70 carbon steel plate.
• Applications: Gr 70 for high-pressure, severe environments; Gr 65 for balanced needs; Gr 60 for moderate conditions.

10. Why Choose Gangsteel?

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

• Quality: Rigorous testing for HIC, NACE, and ASTM compliance.
• Global Delivery: Efficient logistics for ASTM A516 and related standards like ASTM A387, ASTM A514, and EN 10028-3.
• Customization: Tailored A516 GR 70 Plate thickness and sizes.
• Support: Expertise for selecting among ASTM A517, ASTM A203, or JIS G3103.

11. Conclusion

ASTM A516 Gr 70 excels in high-pressure, sour gas environments, offering superior strength compared to Grades 65 and 60, which prioritize weldability and ductility. For projects requiring robust performance, choose ASTM A516 Gr 70 plate; for moderate needs, consider Grades 65 or 60, or explore alternatives like ASTM A662, ASTM A225, or ASME SA353. Contact Gangsteel or visit our product page for quotes and support.