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 its good machinability, wear resistance and vibration damping properties.
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.
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 are a result of larger graphite flakes and not as 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)|
|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|
|* 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%|
|* 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 .|