SA 516 Gr 70n material Specification

SA 516 Gr 70N Material Specification

SA 516 Gr 70N is a normalized carbon steel plate grade under ASME SA-516/SA-516M (identical to ASTM A516 Grade 70), designed for welded pressure vessels in moderate and lower-temperature service. The "N" denotes normalization, ensuring enhanced notch toughness and uniformity, making it ideal for high-pressure applications in cold environments.

This article details the material specifications of SA 516 Gr 70N, including chemical composition, mechanical properties, delivery conditions, and applications, with comparisons to related grades like ASME SA 516 Gr 65, ASME SA 516 Gr 60, and ASME SA 516 Gr 55. For more details, visit our ASME SA 516 Gr 70 steel plate.

Overview of SA 516 Gr 70N

SA 516 Gr 70N is a high-strength carbon steel plate for pressure vessels, with normalization ensuring a fine-grain microstructure for improved toughness, especially at low temperatures. It is part of the ASME SA-516 standard, which includes four grades (55, 60, 65, 70) based on tensile strength. Gr 70N offers the highest strength and mandatory impact testing at -46°C, ideal for critical applications like boilers and petrochemical tanks.

Key Features:

• Standard: ASME SA-516/SA-516M (aligned with ASTM A516-06 or later).
• Grade Designation: Gr 70 [485], indicating tensile strength of 485-620 MPa; "N" for normalized condition.
• Processing: Fully killed steel with fine austenitic grain size (No. 5 or finer per ASME SA-20).
• Applications: High-pressure vessels, offshore structures, and low-temperature storage systems.

SA 516 Gr 70N Chemical Composition

The chemical composition of SA 516 Gr 70N is controlled to ensure weldability and toughness:

Key Notes:

• Carbon (C): ≤0.27% (heat) / 0.31% (product) balances strength and weldability; higher carbon (up to 0.31%) for >100 mm plates.
• Manganese (Mn): 0.85-1.20%; for each 0.01% carbon reduction below max, Mn can increase by 0.06% up to 1.50%.
• Phosphorus (P) and Sulfur (S): Low levels (≤0.025% and ≤0.015%) minimize inclusions for enhanced toughness.
• Silicon (Si): 0.15-0.40% aids deoxidation and strength.

Carbon Equivalent (CEV): Typically ≤0.43%, calculated as CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15, ensuring excellent weldability.

SA 516 Gr 70N Mechanical Properties

The mechanical properties of SA 516 Gr 70N are optimized for high-pressure and low-temperature service:

• Yield Strength: ≥260 MPa (38 ksi) for ≤25 mm, decreasing to 235 MPa for >100 mm, supporting high-pressure vessels.
• Tensile Strength: 485-620 MPa (70-90 ksi) ensures durability under pressure.
• Elongation: ≥27% for ≤25 mm, supporting formability.
• Impact Toughness: ≥27 J (20 ft-lb) at -46°C (Charpy V-notch, longitudinal) for >13 mm, mandatory for normalized condition, ensuring low-temperature reliability.
• Hardness: Typically 150-190 HB (Brinell), balancing machinability and strength.

Delivery Conditions and Specifications

Per ASME SA-516, SA 516 Gr 70N specifications include:

• Condition: Normalized for all thicknesses to ensure fine-grain microstructure and enhanced toughness.
• Thickness Range: Up to 100 mm (4 inches); custom thicknesses up to 200 mm available.
• Widths/Lengths: Up to 3000 mm width, 12,000 mm length.
• Testing:
  • Tension testing per ASME SA-20 for yield and tensile strength.
  • Mandatory Charpy V-notch impact testing at -46°C for >13 mm thickness.
  • Ultrasonic examination (UT) per SA-435/SA-578 (optional) for internal quality.
• Marking: Includes grade (Gr 70N), heat number, thickness, and manufacturer stamp.
• Certifications: EN 10204 3.1/3.2 certificates, ASME SA-516 compliance, ABS/LR/BV/DNV approvals for marine/pressure vessel use.

The full specification is available in the ASME SA-516 PDF, purchasable from ASME.org or accessible via excerpts on sites like MetalPiping.com.

Welding and Heat Treatment

SA 516 Gr 70N is highly weldable due to its normalized condition and low carbon content:

• Welding: Compatible with SMAW, GMAW, and SAW per ASME Section IX. Preheating (149-204°C for >38 mm) prevents hydrogen-induced cracking; PWHT (593-649°C) for stress relief in thick sections or critical welds.
• Consumables: E7018 electrodes for SMAW (low-hydrogen, 70 ksi tensile); ER70S-6 wire for GMAW; EM12K flux with EH14 wire for SAW.
• Weldability: Low carbon (≤0.27%) and CEV (~0.43%) ensure robust welds with minimal brittleness, ideal for pressure vessel fabrication.

Comparison with Other SA 516 Grades

Key Difference: SA 516 Gr 70N is always normalized, ensuring superior toughness compared to Gr 55, Gr 60, and Gr 65 (which are as-rolled for ≤38 mm). It has the highest strength and mandatory -46°C impact testing, ideal for critical high-pressure and low-temperature applications.

Applications

SA 516 Gr 70N is used in:

• Pressure Vessels: High-pressure boilers and tanks for -46°C to 343°C service.
• Offshore Structures: Components requiring high strength and toughness in cold marine environments (e.g., Arctic seas).
• Petrochemical Tanks: Low-temperature storage for LNG or other liquids, leveraging normalized toughness.

Explore ASME SA 516 Gr 65 for slightly lower strength needs.

Why Choose Gangsteel?

Gangsteel supplies SA 516 Gr 70N:

• Inventory: Extensive stock in China for rapid availability.
• Sizes: Thickness 6–200 mm, widths up to 3000 mm, lengths up to 12,000 mm.
• Delivery: 7-30 days to global markets.
• Certifications: ASME SA-516, EN 10204 3.1/3.2, UT testing per SA-435/SA-578, ABS/LR/BV/DNV approvals.
• Processing: Cutting, rolling, bending to meet project specifications.

Contact us for ASME SA 516 Gr 70 steel plate.

FAQ

What is the SA 516 Gr 70N material specification?
The SA 516 Gr 70N specification under ASME SA-516 includes yield strength ≥260 MPa, tensile strength 485-620 MPa, elongation ≥27%, mandatory impact toughness ≥27 J at -46°C, and normalized condition for pressure vessels.

What is the carbon content of SA 516 Gr 70N?
SA 516 Gr 70N has a maximum carbon content of 0.27% (heat analysis), ensuring weldability and toughness for high-pressure applications.

How does SA 516 Gr 70N compare to ASME SA 516 Gr 65?
SA 516 Gr 70N has higher yield (260 MPa vs 240 MPa) and tensile strength (485-620 MPa vs 450-585 MPa) than Gr 65, with mandatory normalization for enhanced toughness, ideal for high-pressure vessels.

Is SA 516 Gr 70N weldable?
Yes, SA 516 Gr 70N is highly weldable with low carbon (0.27%) and CEV ~0.43%, using SMAW/GMAW with preheating (149-204°C for >38 mm) and PWHT for thick sections.

What applications use SA 516 Gr 70N?
SA 516 Gr 70N is used in high-pressure pressure vessels, boilers, petrochemical tanks, and offshore structures for -46°C to 343°C service, leveraging normalized toughness.

How does SA 516 Gr 70N compare to ASME SA 516 Gr 60?
SA 516 Gr 70N has higher carbon (0.27% vs 0.21%), yield (260 MPa vs 220 MPa), and tensile strength (485-620 MPa vs 415-550 MPa) than Gr 60, with mandatory -46°C testing and normalization vs optional for Gr 60.