The core difference between cast iron valves and ductile iron valves lies in the inherent properties of the materials and the resulting performance differences:
Cast iron valves typically refer to gray cast iron valves, where the graphite has a flake-like structure, while ductile iron valves undergo spheroidization treatment to distribute the graphite in a spherical shape, significantly improving mechanical properties.
Material and Structural Differences
Cast iron (gray cast iron) grades are typically HT200-300, where carbon exists in the form of flake graphite, causing the matrix to fracture, resulting in lower strength and plasticity. Ductile iron grades, such as QT450-10, have spherical graphite, reducing damage to the matrix and giving the material both high strength and good toughness.
Appearance and Physical Properties
Surface Color: Ductile iron valves have a gray and glossy surface, while cast iron valves are mostly dark gray or black.
Density and Weight: Ductile iron has a higher density, making valves of the same specifications heavier. Microstructure: Ductile iron has a smoother surface, while gray cast iron may contain porosity.
Performance Comparison:
Mechanical Properties: Ductile iron exhibits significantly superior strength, plasticity, and impact resistance compared to cast iron, approaching the levels of medium carbon steel.
Corrosion and Wear Resistance: Due to its dense structure, ductile iron offers superior corrosion and wear resistance.
Applicable Pressure and Temperature: Cast iron valves are suitable for low-temperature, low-pressure environments (such as water systems) with PN≤1.0MPa and -10℃~200℃; ductile iron valves can withstand higher pressures and temperatures with PN≤4.0MPa and -30℃~350℃.
The above outlines the performance differences between valves produced using the two casting processes. Of course, if you have a large-scale custom casting valve requirement, you can choose to cooperate with Mulan Metal. Mulan Metal has 12 years of experience in metal casting production and processing, and has helped clients in over 30 countries complete various commissioned production of casting products, receiving consistent praise. We look forward to your cooperation inquiries.
Here is our Custom Castings Sample Display：
