What Is the Difference between Gray Iron and Ductile Iron?

HEBEI YOGEM produces two different types of iron castings each working day.

Our foundry is fully equipped to handle a wide range of component casting complexities and sizes, from one pound to 6,000-pound molds. Customers can provide their own patterns or allow our highly trained team to design in-house patterns. We have the ability to work with more than 100 different grades of iron and steel, including specialty metals such as high-chrome irons.

Iron is generally divided into two categories: gray iron and ductile iron. They are differentiated by the form and structure of carbon present within the metal. They each have unique properties that make them more or less beneficial for certain applications. Our team of melters, pourers, and metallurgical experts are experienced in gray iron casting and ductile iron casting.

Gray iron

Gray Iron: Lower Cost and Higher Vibration Dampening

Gray iron, the oldest commonly used form of cast iron, consists of flake graphite in a pearlitic matrix. Gray iron is weak in tension and strong in compression. It behaves like a brittle material when under stress and fails in tension without significant plastic deformation. Gray iron is easy to manufacture and machine and has excellent vibration dampening characteristics. These properties make gray iron an excellent choice for machine bases, engine blocks, motor housings, gearboxes. It is also best for other metal components where moderate strength is needed, but impact resistance and ductility are not.

Ductile iron

Ductile Iron: Higher Strength and Better Performance

Ductile iron, developed as recently as the middle of the 20th century, is made using a Magnesium ladle addition to condense the graphite flakes into nodules during solidification. With the graphite in this form, the resulting metal behaves (to a much greater degree) according to the properties of the ferritic or pearlitic matrix surrounding the nodules. The material properties are no longer simply dominated by brittle fracture along the graphite flakes in gray iron. The resulting metal has higher strength than gray iron and will exhibit plastic deformation before failure. Therefore, a Ductile Iron casting will behave in a manner that is in between the rigid and brittle behavior of a Gray Iron casting and the soft and very ductile behavior of low carbon steel. Ductile Iron, while being more difficult to manufacture than Gray Iron, is still much cheaper to produce than steel. This combination makes Ductile Iron castings the best choice for ferrous casting components for which the stress, strain, and fatigue requirements are met by one of its many and diverse standard grades.

Attribute Comparison Chart for Gray Iron vs. Ductile Iron

Choose Willman for Quality and Dependability!

HEBEI YOGEM has open capacity for new projects for both large and small castings.  We produce most of the commonly used grades of gray iron and ductile iron.  So send us the drawings and specifications of your latest project today and we will provide timely feedback and/or quotations.  If you are experiencing a crisis with your current supply chain, call us. We have the management horsepower to quickly step into the breach.