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Ductile Iron ASTM A536 Grade 120-90-02

Posted by Penticton Foundry on February 2, 2021

Related Standards – SAE J434c, UNS F36200, EN-JS 1080, ISO 800-2

A foundry worker pours ASTM A536 120 – 90 – 02 ductile iron

Martensitic Ductile Iron (120-90-02) has low to zero pearlite formation due to specific alloy additions, and can be quite hard and brittle in its untempered form. A quench and temper heat treatment process is used to develop extremely high strength and wear resistant material, with low levels of ductility and toughness. This quench and temper process also allows the martensitic ductile iron to be machined.

Unlike austempered ductile irons, the heat treatment required to produce 120-90-02 can be performed at some foundries and most commercial heat treaters. It is important to temper the casting soon after quenching to relieve internal stresses. Chemistry requirements are not specified in the ASTM A536 standard. Chemistry and hardness listed in this spec would be typical for a Grade 120-90-02.

Chemistry requirements are not specified in the ASTM A536 standard. Chemistry and hardness listed in this spec would be typical for a Grade 120-90-02.

Composition

CMnSiCrNiCuMg
Min%3.00.151.50.030.050.150.03
Max%3.81.002.80.070.21.000.06

Physical and Mechanical Properties

UTS (ksi)120000
TS (ksi)90000
%Elongation min2%
Hardness (BHN)270-331
Density (lb/in3)0.257-0.260
Thermal Conductivity (Cal/cmsec °C)0.074
Specific Heat at 70F (Btu/lb°F)0.12
Melting Temperature (F)2120

Machinability

Determining machinability is often linked to hardness, due to the connection between hardness and microstructure. This is true for similar microstructures, but a tempered martensitic matrix will demonstrate better machinability than a pearlitic matrix of a similar hardness.

Read: “Ductile Iron Machining Advantages” for more information on the machining advantages ductile iron.

Design Advantages with 120-90-02

  • High Strength
  • Good Wear Resistance
  • Machinability

Pro Tip: The blog, “Top 5 Design Mistakes in Ductile Iron Castings” offers trouble shooting tips for designing with ductile iron.

Preferred applications

  • Pinions
  • Gears
  • Rollers
  • Slides

Read: To learn more about ductile iron, check out our ductile iron webpage.

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