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Alloy Comparison Including Chrome White Iron

Posted by Penticton Foundry on September 24, 2015

 Wondering Which Iron Alloy to Use?

High Chrome White Iron (ASTM A532)
  • High chrome white iron is composed of Carbides and Martensite (among the hardest phase of iron alloys).

  • This combination makes chrome white iron exceptionally wear-resistant and strong, but gives it virtually no toughness.

  • When solving wear-related problems chrome white iron should be one of the first materials you explore.
Note: We have perfected our process to provide castings that exhibit consistent through-hardnesses for different thicknesses.  We are also able to fully machine our HCWI and supply it to you in the hardened state.
Ductile Iron
(ASTM A536)
  • Ductile Iron has spheres of graphite in it, as opposed to gray iron which has flakes of graphite in it.

  • These spheres give ductile iron its ability to flex, or be forgiving (ductile).

  • The rest of the microstructure can be fully ferritic (low strength) or fully pearlitic (high strength).

  • We commonly pour the 60-40-18, 65-45-12, 80-55-06 and 100-70-03 grades. We will also pour the 120-90-02 grade if you require it.

  • The first number represents the material’s ultimate tensile strength (in ksi), the second number represents the material’s yield strength (in ksi) and the third number represents the material’s elongation (in percentage).

  • Any time you need to design a component with a fabrication or casting think about using ductile iron.

  • You can generally replace a steel fabrication with a ductile iron casting.

  • Ductile iron is much stronger than gray iron, but it also has flexibility (ductility) and will stretch or bend (like steel) before it fails.

  • Ductile iron is very cost effective and is easily cast into very complex shapes:  cable drums, planetary hubs, transmission housings, bearing housings, motor housings, support brackets, pump casings, impellers, stuffing boxes, pedestals, gears, gear housings, sheaves and pulleys are just a few of the parts that can be made in ductile iron.

  • Industries served include oil and gas, OEM, automotive, railroad, truck, agriculture, construction, pump and mining.

Austempered Ductile Iron (ASTM A897)
  • Austempered ductile iron is made by taking high quality ductile iron and heat treating it so that it is composed of acicular ferrite and ausferrite. 

  • ADI’s strengths will be double those of ductile iron’s, while still retaining some elongation (ductility).

  • High strength, lightweight castings can be manufactured using ADI and in many instances it will perform better than other materials – for a lower cost.

  • Penticton Foundry makes seven different grades of ADI, including Carbidic ADI; which is the most wear-resistant of the ADI grades.
  • Austempered Ductile Iron (ADI) has great strength, good wear resistance and a great strength-to-weight ratio. 

  • It can be used anywhere ductile iron is used.

  • It can replace cast steel or even forged steel in some instances. 

  • It can even be made thin enough to replace aluminum components, saving weight as a result. 

  • Industries served include automotive, truck, agriculture and OEM. It is typically used for gearboxes, powertrain components, drivetrain components and structural components.

 Gray Iron (ASTM A48)
  • Gray iron has flake graphite in it – results in non-existent ductility and the low strength.

  • It will not bend if stressed beyond its tensile strength and will fracture without warning.

  • Gray iron, however, is still one of the most widely used alloys.  One just has to design within its limits.
  • Gray Iron does not possess any ductility, but it is one of the best alloys money can buy for its damping capacity and resistance to thermal shock.

  • It’s typically used for engine blocks, counter weights, municipal castings, machine bases, pump casings, housings, water pipes and fittings.

  • Class 20, Class 30 and Class 40 are commonly poured gray irons.

Other Irons

Gray Heat Resistant
(ASTM A319)

High Temperature Ductile (ASTM A395)

Austenitic Gray Ni-Resist (ASTM A436)

Austenitic Ductile Ni-Resist (ASTM A439)

Bullets Apply to All Irons in Far Left Column

  • These irons withstand high temperatures

  • They are used for components ranging from exhaust-gas-turbocharger housings to industrial furnace parts.

  • Contact Penticton Foundry if you have any questions about irons with elevated temperature properties.