65-45-12 Ductile Iron

Dura-Bar 65-45-12 ductile iron contains nodular graphite in a matrix of ferrite with small amounts of pearlite. The ferritic structure gives excellent machinability with good surface finishes along with optimal impact strengths, fatigue properties, electrical conductivity and high magnetic permeability. This iron has approximately the same tensile and yield strengths as AISI 1020 steel in the as-rolled condition. This specification conforms to ASTM A536 grade 65-45-12. Download the 65-45-12 Ductile Iron Product Brief.

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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 65-45-12 can be oil quench hardened from 1600° F (885° C) to Rockwell C 50 minimum on the outside of the bar. Hardness in the core will be less than the hardness on the outside surfaces. Any grade of ductile iron can be quenched and tempered to 50–55 Rc.

This grade also responds well to surface hardening methods such as flame or induction heat treating. It is well suited for austempering because of the low residual alloy content, and the highly ferritic matrix provides predictable growth with minimal heat-distortion. Get more details including typical Jominy end quench curve, methods and cycle times, and temperature effects by downloading the Dura-Bar Heat Treating Guide.

Stock Sizes: 65-45-12 and 65-45-12X


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: 2.150" x 2.930" to 20.000" x 25.600"

Size Range Squares: 2.180" x 2.180" to 21.000" x 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

*Carbon and silicon targets are specified for each bar size in order to maintain mechanical properties. Magnesium is added as an inoculant to produce nodular graphite.

Sulfur0.025% Max
Phosphorus0.05% Max

Mechanical Properties

Hardness properties for various diameters are shown in the table. Hardness properties listed are minimum and maximum across the bar. For rectangles, squares and shapes, 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. In bars under 2.0" diameter, elongation will be 9% minimum.

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

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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