BS2789 Grade 700-2 SG Iron: Properties, Equivalents, and Applications 

BS2789 Grade 700-2 is a high-strength Spheroidal Graphite (SG) Iron, also known as ductile iron, engineered for applications demanding exceptional wear resistance and high tensile strength. This material provides a unique combination of properties that make it a superior alternative to certain cast steels and lower-grade irons. For engineers and procurement managers in demanding sectors, understanding the capabilities of Grade 700-2 is essential for designing and manufacturing durable, reliable components. 

At Nifty Alloys LLC, we specialize in the supply of high-integrity engineering materials, including a comprehensive range of BS2789 SG Iron grades. This guide provides a detailed technical overview of Grade 700-2, covering its chemical composition, mechanical properties, equivalent standards, and industrial applications to support your material selection process. We ensure every product we supply meets rigorous international standards, providing you with certified materials for critical operations. 

What is BS2789 Grade 700-2 SG Iron 

BS2789 Grade 700-2 is a specific grade of ductile iron defined by the British Standard BS2789, which governs Spheroidal Graphite or Nodular Cast Iron. The designation "700-2" directly refers to its minimum mechanical properties: a tensile strength of 700 MPa and a minimum elongation of 2%. This grade achieves its high strength and hardness through its pearlitic microstructure, which is developed during the casting process or through subsequent heat treatment. 

Unlike grey cast iron, where graphite exists as flakes, SG iron contains graphite in the form of spheroids or nodules. This structural difference is achieved by adding nodulizing elements, such as magnesium, to the molten iron. The rounded graphite nodules act as "crack arresters," preventing the propagation of fractures and giving the material its characteristic ductility, toughness, and high strength. Grade 700-2, with its predominantly pearlitic matrix, is optimized for strength and wear resistance, making it ideal for heavy-duty engineering components subjected to significant stress and fatigue. 

Key Features & Advantages 

Choosing BS2789 Grade 700-2 SG Iron provides several distinct advantages for high-performance applications. Its unique microstructure delivers a combination of properties that are difficult to achieve with other materials in its price range. 

• Exceptional Tensile and Yield Strength: With a minimum tensile strength of 700 MPa, it can replace more expensive forged steel components in certain applications, offering significant cost savings without compromising performance. 
• Excellent Wear and Abrasion Resistance: The high hardness (229-302 HBW) and pearlitic matrix provide a durable surface that withstands friction and abrasive wear, extending the service life of components like gears, rollers, and dies. 
• Good Machinability: Despite its hardness, Grade 700-2 offers better machinability than cast steels of similar strength. This results in faster production times, reduced tool wear, and lower manufacturing costs. 
• Superior Castability: As a cast iron, it can be formed into complex and intricate shapes, allowing for design freedom and the integration of multiple parts into a single casting. This reduces the need for welding or assembly. 
• Consistent and Homogeneous Microstructure: The spheroidal graphite nodules provide a uniform material structure, ensuring predictable and reliable mechanical properties throughout the component. This consistency is critical for safety and performance in demanding applications. 
• High Fatigue Strength: The material's ability to resist cyclical loading makes it ideal for components subjected to repeated stress, such as crankshafts, connecting rods, and press components.