What Is Ductile Iron Casting?

Ductile iron casting is the solid metal object that results from molten ductile iron being poured into a cavity of a mold. In melting, magnesium and cerium are added to molten cast iron. After cooling and solidified, we get the desired shapes.

Ductile iron is also known as ductile cast iron, Spheroidal Graphite Iron. It essentially is an iron-carbon alloy. The carbon content in cast iron is greater than 2%. Ductile Iron contains spheroidal (nodular) shaped graphite. It is higher strength than Gray Iron. weighs about 10% less than steel for the same section size.

Ductile Iron castings are produced for applications requiring strength, toughness, good machinability, and low cost. So important elements like silicon, manganese, sulfur, phosphorus, etc. can be added to the cast iron. That changes the structure and properties of the resulting alloys.

Ductile cast iron (also called spheroidal graphite cast iron or nodular cast iron) has been widely used as the main industrial material in place of high-grade cast iron. Although most varieties of cast iron are comparatively brittle, ductile iron castings are much more ductile due to the inclusion of nodular graphite.

Benefits of Ductile Iron Casting

  • high strength, ductility and wear resistance. These qualities allow for a much higher tensile and yield strength as well as a lower damping capacity.
  • low melting point, good fluidity and machinability. superior castability and machinability.
    excellent strength to weight ratio.
    Ductile iron casting cost is lower than steel castings.
  • Compared to grey iron casting, ductile iron has much more impact and fatigue resistance
  • Near net shape, ductile iron investment castings provide the design engineer with the best combination of part design, surface hardening ability, elasticity modulus, corrosion resistance, and strength versus weight ratio.

Ductile Iron Investment Casting Applications

Ductile iron castings have many useful characteristics and cost-effective alternatives to other ferrous alloys. Additionally, ductile irons are widely used in numerous industries including:


Due to their increased strength and ductility, Ductile Iron Casting products:

  • Valve Bodies
  • Compressor Valves
  • Couplings
  • Sprocket Wheels
  • Hydraulic Valves & Cylinders
  • Structural Brackets
  • Rollers
  • Cable Drums
  • Frames
  • Pumps
  • Crankshafts
  • Camshafts
  • Exhaust Manifolds
  • Machine frames
  • Flanges
  • Hubs
  • Gear Boxes

Ductile Iron Castings Microstructure

Ductile iron, also referred to as nodular cast iron or spheroidal graphite iron, has an unusual combination of properties obtained because the graphite occurs as spheroids rather than flakes as in gray iron. This mode of solidification is obtained by adding a very small but specific amount of magnesium to molten iron. The allowable content of minor elements that can interfere with the graphite spheroid formation in the base iron is severely restricted. The added magnesium reacts with the sulfur and oxygen in the molten iron and changes the way the graphite is formed.

Ductile Iron Investment Casting Grades

 Tensile strengthYield StrengthDuctility (elongation)Brinell Hardness
ASTM A536 Grade 80-55-06 (SAE D5506)  80 ksi55 ksi6%187-255
  ASTM A536 Grade 60-40-18 (SAE D4018)  60 ksi40 ksi18%187 maximumNominal machining speed of 100 m/mm with carbide tools  
ASTM A536 Grade 65-45-12 (SAE D4512)  65 ksi45 ksi12%156-217  
ASTM A536 Grade 100-70-03 (SAE D7003)  100 ksi70 ksilimited to 3%214-302Nominal machining speed of 66 m/mm with carbide tools.  10% lighter than carbon steel  

Ductile Iron Investment Casting Heat treatment –Austempered

Austempering is a heat treat process developed to improve the strength and toughness of ferrous alloys like ductile iron. As-cast ductile iron can be austempered to achieve greater tensile and yield strengths as a secondary service.

Ductile Iron Casting in Our Foundry

Ductile iron has greater strength and ductility then gray iron. Those properties allow it to be used effectively in a wide variety of industrial applications, including pipe, automotive components, wheels, gear boxes, pump housings, machine frames for the wind-power industry, and so on.

Our ductile iron foundry can make ductile iron casting in different grades, such as QT400-15, QT400-15, QT450-10, QT500-7, QT600-3, etc. Together with grey iron castings, we can supply ductile iron castings both in lost foam casting and sand casting processes. Our full scale services of ductile iron casting include: Casting, heat treatment, machining and more.

Our company works collaboratively with clients to determine the best material grade and production process for each custom ductile iron castings. Contact us for your request and get more information about our solution that matches your project.

JC Casting has been providing near net-shaped ductile iron investment castings for nearly 20 years. Our world class 175,000 square foot facility features the industry’s most technologically advanced equipment to service your high volume ductile iron investment casting project needs.

Our company works collaboratively with clients to determine the best material grade and production process for each custom ductile iron castings. Contact us for your request and get more information about our solution that matches your project.