ASTM A662 Grade C is a type of carbon-manganese-silicon steel plate used for welded pressure vessels, boilers, and storage tanks, especially where moderate to lower temperatures are involved and improved low-temperature toughness is needed, characterized by its higher manganese content (0.92-1.72%) for enhanced strength compared to Grades A and B. Key properties include a minimum yield strength of 295 MPa and specific chemical limits, with plates typically normalized for thicknesses over 40mm.
A662 Grade C pressure vessel steel chemical composition %
| Grade | C max | Mn | P max | S max | Si max |
| A662 Grade C | 0.20 | 1.00-1.60 | 0.025 | 0.025 | 0.15-0.40 |
A662 Grade C pressure vessel steel Mechanical properties
| Class | Tensile strength Rm MPa | Yield strength ReH MPa min | Elongation A% min in | |
| 200mm | 50mm | |||
| A662 Grade C | 485-620 | 295 | 18 | 22 |
A662 Grade C Processing Flow
Raw Material Preparation:
Select high-quality pig iron, scrap steel and alloy additives (manganese, silicon) that meet the standard requirements. Conduct pre-inspection of raw materials to ensure no excessive harmful impurities (sulfur, phosphorus) and stable chemical composition, laying a solid foundation for subsequent processing.
Smelting & Refining:
Put the prepared raw materials into an electric arc furnace (EAF) or basic oxygen furnace (BOF) for smelting at high temperature (above 1600℃) to form molten steel. Then transfer the molten steel to a ladle refining furnace (LF) for secondary refining, including desulfurization, deoxidation and composition adjustment, to ensure the uniformity and purity of the molten steel.
Casting & Billet Forming:
Pour the refined molten steel into continuous casting molds through continuous casting process to produce steel billets of specified specifications. After casting, the billets are cooled naturally or by controlled cooling to room temperature, and then undergo surface inspection and cutting to remove defective parts (such as cracks, inclusions).
Hot Rolling & Shaping:
Heat the qualified steel billets to 1100-1250℃ in a heating furnace and keep them warm for a certain time. Then send the billets to the hot rolling mill for multi-pass rolling, and precisely control the rolling pressure, speed and cooling rate (controlled rolling and controlled cooling technology) to form steel plates of required thickness, width and flatness. After rolling, the steel plates are cut to fixed lengths.
Heat Treatment:
Perform normalizing heat treatment on the rolled steel plates. Heat the plates to 890-950℃, keep them at a constant temperature for 30-60 minutes (depending on thickness), and then cool them in air. This process optimizes the microstructure, eliminates internal stress, and improves the low-temperature toughness and mechanical properties of the steel plates.
Surface Treatment:
Carry out shot blasting, pickling and passivation on the heat-treated steel plates. Shot blasting removes oxide scales and surface impurities; pickling and passivation further clean the surface and form a thin protective film, enhancing initial corrosion resistance.
Inspection & Testing:
Conduct comprehensive inspection on the finished steel plates, including chemical composition analysis (spectrometer testing), mechanical property testing (tensile test, impact test), dimensional inspection (thickness, width, flatness) and surface quality inspection. Only products that meet the ASME and relevant industry standards are allowed to leave the factory.
Cutting & Machining (for Application):
According to the actual needs of downstream applications (such as pressure vessels, pipelines), the qualified steel plates are cut into specified sizes by plasma cutting, flame cutting or shearing. Then carry out subsequent machining (drilling, bending, welding) to manufacture finished components that meet the equipment assembly requirements.
A662 Grade C Applications
Petrochemical Industry:
As a specialized steel for medium and low-temperature pressure vessels, it is mainly used to manufacture critical equipment (reactors, heat exchangers, storage tanks, etc.). It operates stably at -30℃ and above, resisting medium pressure and corrosion to ensure safe petrochemical production.
Power Energy Industry:
Suitable for high-temperature and high-pressure equipment (boiler drums, nuclear reactor pressure vessels, etc.). It withstands alternating temperature conditions and ensures long-term safe operation of power generation equipment with excellent strength and fatigue resistance.
Low-Temperature Storage and Transportation Field:
Used in low-temperature medium (liquid ammonia, LPG, etc.) storage and transportation containers. Adaptable to -20℃ to -45℃ environments, it meets strict requirements for toughness and sealing.
Water Conservancy and Hydropower Field:
Applicable to pressure-bearing components (high-pressure water pipes, turbine volutes, etc.) in hydropower stations. It retains good mechanical properties in low-temperature water, ensuring stable operation of water conservancy facilities.
Request a professional quotation for A662 Grade C from GNEE Steel.
What welding processes are suitable for A662 Grade C?
Suitable welding processes include shielded metal arc welding (SMAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW), and submerged arc welding (SAW), depending on application scenarios.
What is the coefficient of thermal expansion of A662 Grade C?
The coefficient of thermal expansion is about 11.7×10⁻⁶ /°C (6.5×10⁻⁶ /°F) between 20-100°C, which is important for thermal stress calculation in high-temperature environments.
Can A662 Grade C be used in high-pressure applications?
It is suitable for moderate-pressure applications. For high-pressure environments (exceeding its pressure rating), higher-strength alloy steels or special materials should be selected instead.
What is the fatigue strength of A662 Grade C?
The fatigue strength (at 10⁷ cycles) of A662 Grade C is approximately 190-220 MPa at room temperature, which is important for components subjected to cyclic loads.
What surface treatments are applicable to A662 Grade C?
Common surface treatments include shot blasting, pickling, phosphating, painting, and galvanizing. These treatments improve corrosion resistance and surface quality for different service environments.
What is the difference between A662 Grade C and A516 Grade 60?
A662 Grade C is for low-temperature service with better toughness, while A516 Grade 60 is for general pressure vessels. A516 Grade 60 has higher strength but lower low-temperature toughness.
Can A662 Grade C be machined easily?
Yes, it has good machinability. It can be processed by turning, milling, drilling, and other common machining methods with appropriate cutting tools and parameters.
What is the maximum operating temperature of A662 Grade C?
The maximum continuous operating temperature of A662 Grade C is about 425°C (800°F). Beyond this temperature, its strength and toughness will decrease significantly.
Does A662 Grade C have any notch sensitivity?
It has low notch sensitivity, especially at low temperatures. The Charpy V-notch impact test confirms that it can resist fracture even with notches in the structure.
What quality control measures are taken for A662 Grade C production?
Production quality control includes raw material inspection, melting process monitoring, rolling process control, heat treatment verification, and final mechanical and chemical testing to meet ASTM standards.