Understanding ASTM A240 Gr. 347H Plate Specifications
ASTM A240 Gr. 347H is a specification developed by ASTM International that covers chromium, nickel, and manganese-containing austenitic stainless steel plates, sheets, and strips for pressure vessels and general applications. Let’s delve into the key aspects of the ASTM A240 Gr. 347H Plate specifications to gain a comprehensive understanding.
ASTM A240 Gr. 347H plates are high-temperature austenitic stainless steel plates that conform to the specifications outlined by ASTM International, a globally recognized standards organization. The “A240” in the designation refers to the standard specification for chromium and chromium-nickel stainless steel plates, sheets, and strips for pressure vessels and general applications. The “Gr. 347H” indicates that the specific grade of stainless steel is 347H.
Chemical Composition of ASTM A240 Gr. 347H Plate
The chemical composition of ASTM A240 Gr. 347H is crucial for determining its mechanical and corrosion-resistant properties. The main elements include:
Chromium (Cr): Chromium is a key component for enhancing corrosion and oxidation resistance in ASTM A240 Gr. 347H, chromium content typically ranges from 17% to 20%.
Nickel (Ni): Nickel contributes to the alloy’s strength and corrosion resistance. The nickel content in 347H is between 9% and 13%.
Manganese (Mn): Manganese helps improve the alloy’s mechanical properties and is present in the 2% to 10% range.
Carbon (C): Carbon content is limited to a maximum of 0.04%, ensuring good weldability while maintaining high-temperature strength.
Silicon (Si): Silicon is added for deoxidation and to enhance the steel’s strength.
Phosphorus (P) and Sulfur (S): These elements are controlled to low levels to ensure good weldability and improve the alloy’s overall performance.
Mechanical Properties of ASTM A240 Gr. 347H Plates
ASTM A240 Gr. 347H exhibits excellent mechanical properties, especially at elevated temperatures. Some key mechanical properties include:
Tensile Strength: The material’s tensile strength is typically in the range of 515 to 720 MPa, depending on the heat treatment condition.
Yield Strength: The yield strength, or the point at which the material begins to deform plastically, is 205 to 275 MPa.
Elongation: The alloy demonstrates good elongation, typically around 40% or higher, indicating its ability to deform before breaking.
Hardness: The hardness of ASTM A240 Gr. 347H is influenced by factors such as heat treatment and cold working. Typically, the hardness ranges from 201 to 255 HBW (Brinell Hardness).
Heat Treatment:
Heat treatment plays a significant role in enhancing the mechanical properties of ASTM A240 Gr. 347H. The material is often subjected to solution annealing or annealing at temperatures between 1900°F (1038°C) and 2150°F (1177°C), followed by rapid quenching.
Corrosion Resistance:
One of the key features of ASTM A240 Gr is that 347H is its excellent corrosion resistance, particularly in high-temperature applications. Adding niobium (columbium) to the alloy promotes stabilization against sensitization and intergranular corrosion.
Applications of ASTM A240 Gr. 347H Plate
Due to its high-temperature strength, corrosion resistance, and stability against sensitization, ASTM A240 Gr. 347H finds applications in various industries, including:
Chemical Processing: Used in chemical reactors and vessels where corrosive chemicals are processed.
Heat Exchangers: Employed in constructing heat exchanger components due to their high-temperature resistance.
Oil and Gas Industry: Suitable for applications in oil refineries and offshore platforms where corrosion resistance is critical.
Aerospace: Used in components subjected to high-temperature and corrosive environments.
Weldability:
ASTM A240 Gr. 347H exhibits good weldability and can be easily welded using common welding processes. It is essential to follow proper welding procedures and techniques to maintain the material’s corrosion resistance and mechanical properties.
Conclusion:
In summary, ASTM A240 Gr. 347H is a high-strength, corrosion-resistant stainless steel alloy suitable for various applications, especially in environments with elevated temperatures and corrosive elements. Understanding its chemical composition, mechanical properties, heat treatment, corrosion resistance, and applications is crucial for ensuring this material’s proper selection and utilization in various industries.