Gray Iron Supplier

Dura-Bar® G2 is a pearlitic gray iron containing Type A graphite. G2 is built around ASTM A48 Class 40 gray iron, which is validated from a separately cast bar. These continuous cast bars made to this robust specification are a good fit for a variety of applications due to their good machinability, wear resistance, and vibration-damping properties. Click here to view the Dura-Bar Iron Stock Allowances.

Microstructure of Gray Iron

The microstructure will contain Type VII, A, size 4-6 graphite as defined in ASTM A247. The matrix is fully pearlitic. The edge or rim will consist of Type D, size 6-8 graphite in a matrix that is a combination of pearlite and ferrite. Chill carbides will be less than 5% in any field at 100x and are well dispersed. Dura-Bar® G2 gray iron will contain this type of graphite distribution and will be best suited for applications requiring moderate strength, good vibration damping, and thermal conductivity, along with optimal machining characteristics. Dura-Bar® G2 is built around ASTM A48 Class 40 gray iron. 

Heat Treated Response

Dura-Bar® G2 can be oil quench hardened from 1600° F (885° C) to a minimum hardness of Rockwell C 50 on the outside of the bar. The inside diameter hardness will be less than Rockwell C 50. Lower quench hardness on the inside diameters is a result of larger graphite flakes and not a loss of matrix hardness. Get more details including typical Jominy end quench curve, methods and cycle times, and temperature effects by downloading the Dura-Bar® Heat Treating Guide.

Mechanical Properties (Typical)
Dura-Bar® Grade G2
Tensile Strength (PSI)* 40,000
Hardness (BHN) mid-radius 207-285
Compressive strength (PSI) 120,000
Modulus of elasticity (million psi) 20
Heat-treat response Rc 50 min
Graphite Flake
Microstructure Highly Pearlitic
* As taken from a separately cast test bar. Reduced tensile properties can be expected in larger diameter continuous cast bars.
Chemical Composition (Gray Iron)
Element Grade G2 Gray - Percentage (%)
Carbon* 2.60 - 3.75%
Silicon* 1.80 - 3.00%
Manganese 0.60 - 0.95%
Sulfur 0.07% Max
Phosphorus 0.12% Max
* Carbon and silicon targets are specified for each bar size in order to control the size and shape of the graphite flake.
**Note** Small amounts of alloying elements are used to stabilize the pearlitic structure .

Applications of Gray Iron

Construction & Heavy Equipment

  • Gears, Pulleys


  • Gears, Valve Guides, Numerous Hydraulic Applications, Pump Housings


  • Continuous Caster Rolls, Foot Rolls, Table Rolls, Torch Rolls

Fluid Handling

  • Cylinder Blocks, End Caps, Gear Rack Housings, Glands, Manifolds, Rotors, Valves, Hydraulic Gears, Hydraulic Pistons, Spools, Rollers, Seals, Rotor Liners


  • Bushings, Gears, Gibs, Housings, Pulleys, Rams, Sheaves, Side Frames, Slides, Spindles, Ways

Oil & Gas

  • Bridge Plugs, Cement Plugs, Cones, Mandrels, Retainers, Slips, Slips, Rings, Retainers, Mandrels, Split Rings, Oil Tools/Retainers, Locking Rings, Pony Rods, Plungers


  • Gears, Bushings, Sleeves, Pulleys, Couplings

General Fabrication & Machining

  • Aluminum Molds Plates, Cams, Chain Sheaves, Core Boxes, Dies, Pattern Plates, Wheels, Machine Tool Chucks

Automotive & Transportation

  • Gears, Brake Rotors, Cylinder Liners, Gears, Lash Adjusters, Pulleys, Shock Absorber Pistons, Valve Guides, Valve Seat Inserts