GREY CAST IRONS

Grey flake cast irons are the most used of the general purpose engineering irons. They are relatively inexpensive and easy to produce. They are readily machined and the machined surfaces are resistant to sliding wear. They have high thermal conductivity, low modulus of elasticity and an ability to withstand thermal shock. This makes the material suitable for castings subjected to local or repeated stressing.

The Hi Test (H.T.) range has been developed to cover all grades of grey cast iron in the Australian Standard, AS1830. The following is a summary of the correlated grades.

Hi Test Range

AS1830

 

Grade

Tensile strength, Mpa (min.)

Hardness Class *

Hardness, HB

H.T. 10

T100

100

H145

170 max.

H.T. 12

T150

150

H175

150 to 200

H.T. 14

T200

200

H195

170 to 220

H.T. 17

T250

250

H215

190 to 240

H.T. 20

T300

300

H235

210 to 260

H.T. 23

T350

350

H255

230 to 280

H.T. 26

-

400

-

300+

H.T. Acicular

-

450

-

350+

                   * The number following the "H" indicates the mean brinell hardness.

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