What Is SA662 Grade B
SA662 Grade B is a carbon-manganese-silicon steel plate specified in ASTM A662/A662M, the ASME SA662 adoption, intended primarily for welded pressure vessels operating at moderate and lower temperatures. The grade is designed for service where improved notch toughness is important, giving it an advantage over conventional carbon steel plates in cold-region fabrication.
Chemical Composition
The heat analysis limits for Grade B are carbon 0.25 percent maximum, manganese 0.85 to 1.20 percent, silicon 0.15 to 0.40 percent, phosphorus 0.035 percent maximum, and sulfur 0.035 percent maximum, with slightly wider product analysis tolerances. The controlled manganese and silicon content provides the strength and deoxidation needed for reliable welding and forming.
Mechanical Properties
SA662 Grade B plates have a tensile strength of 450 to 585 MPa, a minimum yield strength of 275 MPa, and a minimum elongation of 20 percent in 50 mm. Charpy V-notch impact testing can be specified at temperatures down to minus 45 degrees C or lower, which is the property that makes the grade suitable for cold-environment pressure equipment.
Heat Treatment and Forming
The plate is generally supplied in the as-rolled or normalized condition. Normalizing at 890 to 950 degrees C followed by air cooling refines the grain structure and improves toughness and uniformity. The material forms readily by cold or hot bending and rolling, and welds without complex preheating or post-weld heat treatment under normal workshop conditions.
Applications
SA662 Grade B is used for low-temperature pressure vessels in cryogenic gas separation and liquefied natural gas processing and storage, storage tanks for liquid oxygen, liquid nitrogen, and refrigerants, and structural components in thermal and nuclear power auxiliary equipment and cold-region industrial plants. Its consistent through-thickness properties support heavy-wall fabrication.
Procurement Guidance
Specify the plate thickness, width, length, and the required impact test temperature and energy when ordering. Plates are commonly available up to 150 mm thick with ultrasonic inspection on request. Request mill test certificates and third-party inspection reports to verify compliance with the applicable standard for your project.
Frequently Asked Questions
Q: What standard covers SA662 Grade B?
A: ASTM A662/A662M, with ASME SA662 as the code adoption.
Q: What is the tensile strength of SA662 Grade B?
A: 450 to 585 MPa with a minimum yield strength of 275 MPa.
Q: Can SA662 Grade B be used at low temperatures?
A: Yes, with impact testing down to minus 45 degrees C or lower as specified.
Q: How does SA662 Grade B differ from SA516?
A: SA662 has higher manganese and silicon content and better low-temperature toughness.
Q: Is SA662 Grade B easy to weld?
A: Yes, with conventional processes and no complex preheating under normal conditions.
Q: What applications suit SA662 Grade B?
A: Low-temperature pressure vessels, LNG processing equipment, and cold-region storage tanks.
Contact us with your specifications for SA662 Grade B plates, including sizes, impact requirements, and delivery schedules.