What are the mechanical properties of ASME SA515 Grade 70 ?
ASME SA515 Grade 70 is a high-temperature carbon steel pressure vessel plate with a minimum tensile strength of 70 ksi(485 MPa), typically ranging 70–90 ksi (485–620 MPa). It features a minimum yield strength of38 ksi(260 MPa) and minimum elongation of17–21%, offering excellent weldability and durability for medium-to-high temperature applications.
ASME SA515 Grade 70 is a silicon-killed carbon steel that prioritizes high-temperature tensile strength over low-temperature ductility. The "coarse-grain" nature of this steel is essential because large grains have less total grain boundary area, which is where creep deformation typically initiates in carbon steels at high temperatures. By maintaining this structure, SA515 Grade 70 provides a stable and reliable material for fusion-welded boilers and pressure vessels. It is meticulously produced to meet the chemistry requirements of the ASME Boiler and Pressure Vessel Code, ensuring that it can safely contain pressurized fluids in the demanding thermal cycles of power generation and chemical refining.
Key Characteristics
High Elastic Modulus: Provides excellent rigidity and resistance to buckling under pressure.
Through-Thickness Integrity: Excellent mechanical properties across the entire cross-section of the plate.
Carbide Stability: Manganes and Silicon levels help stabilize the iron carbides against breakdown at heat.
Thermal Shock Resistance: Capable of withstanding the rapid temperature changes typical of boiler start-up/shut-down.
Grade Designation
Standard Title: Carbon Steel Plates for Intermediate- and Higher-Temperature Service.
Designator: Grade 70.
Group: P-No 1 Group 2 (for welding qualifications).
Comparison with ASTM A36
Pressure Rating: SA515 Grade 70 is a Pressure Vessel Quality (PVQ) steel; A36 is a general structural steel.
Chemical Purity: SA515 has much tighter controls on sulfur and phosphorus to ensure safety under pressure.
Traceability: SA515 requires full Mill Test Reports (MTRs) and pedigree for code vessels; A36 is less strictly documented.
Common Applications
Power Plant Deaerators: Specialized tanks for removing dissolved gases from boiler feedwater.
Petrochemical Feedwater Heaters: Used to preheat fluids in high-pressure refinery lines.
High-Heat Scrubbers: Vessels designed to remove impurities from hot gas streams.
What are the chemical composition of ASME SA515 Grade 70?
The chemical composition of ASME SA515 Grade 70 includes carbon (0.18–0.24%), manganese (0.60–1.00%), silicon (0.13–0.45%), sulfur (0.035% max), phosphorus (0.035% max), and trace amounts of chromium, nickel, and molybdenum. This combination of elements enhances the steel's strength, ductility, and resistance to oxidation, making it suitable for high-temperature applications, such as in boilers and pressure vessels.
What is the fatigue resistance of ASME SA515 Grade 70?
ASME SA515 Grade 70 has good fatigue resistance for most applications in pressure vessels and boilers, where it is subjected to cyclic loading. The material's tensile strength and good weldability help it resist fatigue failures in moderately high-stress conditions. However, for critical applications where fatigue resistance is a primary concern, higher-strength materials or special alloy steels may offer better performance and longevity under extreme cyclic loads.
What is the creep resistance of ASME SA515 Grade 70?
ASME SA515 Grade 70 has moderate creep resistance, which is important for high-temperature applications. Creep resistance refers to the material's ability to resist deformation under long-term exposure to high stress and temperature. While SA515 Grade 70 performs well under typical operating conditions, for extreme high-temperature applications requiring superior creep resistance, other materials with enhanced alloy content, such as SA182 or SA336, may be preferred.
CHEMICAL COMPOSITION OF ASME SA515 Grade 70 STEEL
| C | Si | Mn | P | S | Al | Cr | Cu | Ni | Mo | Nb | Ti | V |
| 0.18 | 0.4 | 0.95/1.50 | 0.015 | 0.008 | 0.02 (Min) | 0.3 | 0.3 | 0.3 | 0.08 | 0.01 | 0.03 | 0.02 |
MECHANICAL PROPERTIES OF ASME SA515 Grade 70
| Tensile strength (ksi) | Yield strength (ksi) | Elongation min, % 200 mm (8 in) | Elongation min, % 50 mm (2 in) |
| 485-620 (70-90) | 260 (38) | 17 | 21 |
1What is the hardness of ASME SA515 Grade 70?
The hardness of ASME SA515 Grade 70 typically ranges between 139 HB to 190 HB, depending on the material's heat treatment. This hardness level is ideal for pressure vessel applications, as it provides a balance between strength, ductility, and impact resistance. The material is strong enough to withstand high pressures while maintaining the necessary ductility to resist cracking under stress.
2What is the welding ability of ASME SA515 Grade 70?
ASME SA515 Grade 70 has good weldability, which makes it ideal for use in fabricating pressure vessels, heat exchangers, and boilers. Preheating may be necessary for thicker sections to prevent cracking, and post-weld heat treatment is often recommended to relieve residual stresses and improve mechanical properties. Low-hydrogen electrodes are usually used to minimize the risk of hydrogen-induced cracking during the welding process.
3What is the tensile strength of ASME SA515 Grade 70?
ASME SA515 Grade 70 has a tensile strength range of 485–620 MPa and a yield strength of approximately 205 MPa. It also offers good elongation (around 20%) and impact resistance, which makes it suitable for high-pressure environments. These properties allow the steel to perform reliably in applications where mechanical stress and high temperatures are present, such as in pressure vessels, heat exchangers, and boilers.
4What is the cost of ASME SA515 Grade 70?
The cost of ASME SA515 Grade 70 is typically higher than standard carbon steels due to its alloy content and high-strength properties. However, the added cost is justified by the material's performance in demanding applications, such as pressure vessels and heat exchangers. Its ability to withstand high temperatures and pressures makes it a cost-effective choice in industries like power generation and petrochemicals, where safety and durability are critical.
5What are the mechanical properties of ASME SA515 Grade 70?
ASME SA515 Grade 70 has a tensile strength range of 485–620 MPa and a yield strength of approximately 205 MPa. It also offers good elongation (around 20%) and impact resistance, which makes it suitable for high-pressure environments. These properties allow the steel to perform reliably in applications where mechanical stress and high temperatures are present, such as in pressure vessels, heat exchangers, and boilers.
6What is ASME SA515 Grade 70?
ASME SA515 Grade 70 is a carbon steel material used for the manufacture of pressure vessels and boilers. It has a high tensile strength and good weldability, making it suitable for high-temperature and high-pressure environments. Commonly used in power plants and chemical processing, Grade 70 offers strength, toughness, and resistance to thermal and mechanical stresses, ensuring durability in critical applications.
7What are the thickness limitations of ASME SA515 Grade 70?
ASME SA515 Grade 70 is available in thicknesses ranging from 3/16 inch (4.8 mm) to 1 1/2 inches (38 mm) for pressure vessel applications. The material is often used in thinner sections where high tensile strength and good weldability are required. For thicker plates, additional considerations for heat treatment and welding processes are necessary to ensure the material performs effectively under high stress and temperature.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff
