Although cast iron flange and ductile iron flange are both iron-based alloy flanges, there are significant differences in manufacturing process, mechanical properties, application scenarios, etc. The specific differences are as follows:
1. Manufacturing process and composition
Cast iron flange: Made of gray cast iron (carbon content 2.5%-4%, silicon 1%-3%) through sand casting, carbon exists in the form of flake graphite. Its production process is simple and does not require additional heat treatment.
Ductile iron flange: Add spheroidizing agents such as magnesium or cerium to gray cast iron to distribute carbon in the form of spheroidal graphite, followed by annealing or normalizing. This process requires strict control of the spheroidization rate (≥80%), in accordance with ASTM A536 standards.
2. Mechanical properties
Tensile strength: cast iron flanges are usually 150-250 MPa; ductile iron flanges can reach 400-600 MPa, and some grades (such as 60-40-18) even exceed 480 MPa.
Toughness and ductility: Cast iron flanges are highly brittle, with an elongation of less than 1%, and are easily broken by impact; ductile iron flanges have an elongation of ≥10%, and their toughness is 5-10 times that of cast iron, and can withstand moderate bending and vibration.
Hardness: The Brinell hardness of cast iron flanges is 150-230 HB; ductile iron flanges are 170-230 HB, and have better wear resistance.
Have any other questions? Welcome to contact us!
3. Corrosion resistance and processability
Corrosion resistance: Both rely on surface treatment (such as galvanizing) to improve corrosion resistance, but ductile iron has a dense structure, and its corrosion rate in a humid environment is about 30% lower than that of cast iron.
Processability: Cast iron flanges are prone to cracking during cutting due to their high brittleness; ductile iron flanges have cutting performance close to that of steel, and can be processed into more precise threads and sealing surfaces.
4. Application Scenarios
Cast iron flanges: Suitable for low-pressure (≤1.6 MPa), non-vibration static systems, such as indoor drainage pipes and low-pressure gas branches, and the price is only 60%-70% of ductile iron.
Ductile iron flanges: Used in medium- and high-pressure (1.6-10 MPa) and vibration or impact situations, such as municipal water supply mains, industrial circulating water pipes, sewage treatment systems, etc., and are widely used in infrastructure projects in the Middle East, Latin America, and other regions.
5. Standards and certifications
Cast iron flanges follow ASTM A126 (gray cast iron flanges) and EN 1561 (European gray cast iron standard); ductile iron flanges are based on ASTM A536 and EN 1563 standards, and their mechanical performance indicators must pass third-party testing (such as SGS material test reports).
Summary
The core difference between the two lies in toughness and strength: cast iron flanges are suitable for low-pressure static conditions, while ductile iron flanges are more suitable for high-pressure dynamic conditions. When choosing, you need to make a comprehensive judgment based on system pressure, working conditions and cost budget.
Yinuo has always focused on providing piping system solutions for customers around the world. Choosing us means that you have a team of experts who have a deep understanding of your industry and specific needs.
Our ductile iron flange pipes are carefully crafted with excellent strength and wear resistance, making them ideal for demanding industrial applications. For users who need efficient branch pipes, our ductile iron flange tees stand out for their reliable performance and convenient installation. Whether your project requires standard sizes or custom specifications, our rich ductile iron flange fittings can meet your needs. Contact us now to experience our trusted quality and reliability.