65-45-12X Ductile Iron

65-45-12X is an all-purpose grade of ductile iron available in larger sizes of rounds and rectangles/squares. With medium strength and ductility, 65-45-12X can be a suitable alternative to low and medium carbon steels. A predominantly ferritic matrix allows for it to be machined as opposed to steels and pearlitic irons, and it is appropriate for applications necessitating fatigue strength and ductility. Download the 65-45-12X Ductile Iron Product Brief, or X Products for all X grades.

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Dura-Bar Ductile Iron 65-45-12


The microstructure consists of Types I & II nodular graphite as defined in ASTM A247. The matrix is ferrite with approximately 5–25% pearlite. The edge or rim will have a higher nodular count and will be mostly ferrite. Chill carbides will be less than 5% in any field at 100x and will be well dispersed.

Microstructure area diagram

Center Area

100x, etched in 5% Nital

65-45-12 ductile iron microstructure at center

Edge Area

100x, etched in 5% Nital

65-45-12 ductile iron microstructure at edge

Heat Treat Response

Dura-Bar 65-45-12X can be heat treated by conventional methods.  Hardening can be accomplished by heating and quenching the material from 1600° F resulting in Rockwell C hardness up to 50 HRC.  Induction and flame hardening can be performed but may require an additional pre-heat treatment to accomplish the desired hardness and microstructure.

Stock Sizes


Size Range:1.500" to 26.560"

As-cast round bars are made to clean up at the nominal size. Additional stock is added to allow for out-of-round and normal imperfections in the as-cast surface. Stock allowance is a function of the bar diameter - see Stock Allowances for details. Other finishes available are Centerless Grinding and Centerless Turning, for demanding tolerance applications.


Size Range Rectangles:17.000" x 30.000" to 20.000" x 25.600"

Size Range Squares:15.354" x 15.534" to 21.000" to 21.000"

As-cast rectangles and squares are made to the actual size with no allowance for machine stock added. Rectangles and squares are cast to actual dimension, with clean up stock dependent on the height and width ratio. See Stock Allowances for details. Rectangles and squares can be milled to achieve close tolerance benefits - see Services/Milling for details.

Technical Specifications

Chemical Composition

Magnesium is added as an inoculant to produce nodular graphite.

Sulfur0.02% Max
Phosphorus0.08% Max

Mechanical Properties

Hardness properties listed are minimum and maximum across the bar. For rectangles and squares the hardness properties will depend on minimum and maximum section thickness and will be supplied on request.

Size RangeBHN

Tensile strength is determined from a longitudinal test specimen taken from mid-radius of the as-cast bar. 

Mechanical Properties
Tensile strength psi (min)65,000
Yield strength psi (min)45,000
Elongation (min)12%

Typical Applications



Fluid Power:

Cylinder Blocks, End Caps, Gear Rack Housings, Gerotors, Glands, Manifolds, Pistons, Rotors, Valves

Glass Mold:

Bank Molds, Plungers


Bushings, Chuck Bodies, Die Blocks, Flywheels, Gears, Housings, Journals, Pulleys, Rams, Rotary Tables, Side Frames, Spindle Housings, Tie Rod Nuts


Plunger Pin

Power Transmission:

Coupling Hubs, Gears, Pulleys, Sprockets

Pump and Compressor:

Gears, Housings, Pistons, Rotary Screws, Rotors


Coupling Hubs, Gears, Pulleys, Rail Spacers, Sprockets