Cast Irons – Specifications for Gray Iron and Ductile Irons

Gray iron is the original and most common cast iron, so named because of its fracture surface which is typically dark gray in colour. Due to its high carbon content, it has ‘flake graphite’ in its structure. The formation of the flakes or nodules of graphite can be suppressed in part by rapid cooling.

Gray Iron Specifications

Specifications

Typical Properties

Tensile Strength MPa (Ksi)

BHN Hardness

ASTM A-48

CL 25

185 (27)

170

CL 30

225 (33)

175

CL 40

295 (43)

180

ASTM A-319

CL I Type A

185 (27)

175

CL I Type B

200 (29)

180

CL II Type C

290 (42)

190

ASTM A-278

CL 25

185 (27)

170

CL 30

225 (33)

175

CL 40

295 (43)

180

Ductile Iron

Ductile iron was first patented in 1949 after foundrymen searched for the ideal cast iron, which was easy to cast like gray cast iron, but had properties equal to or better than malleable iron. Ductile irons are in fact a family of cast irons characterized by spherical graphite nodules in the structure. These form as a result of the addition of spheroidizers to the cast iron composition.

Ductile Iron Specifications

Specifications

Typical Properties

Tensile Strength MPa (Ksi)

Proportional Limit MPa (Ksi)

Elongation %

Hardness BHN

ASTM A-536

GR 60-40-18

430 (62)

290 (42)

20

170

GR 65-45-12

460 (67)

325 (47)

14

180

GR 80-55-06

575 (83)

400 (58)

7

190

ASTM A-395

430 (62)

290 (42)

20

170

ASTM A-476

575 (83)

400 (58)

7

190

DIN EN 1563

EN-GJS-400-18-LT

420 (61)

270 (39)

20

170

EN-GJS-400-15

430 (62)

290 (42)

17

170

EN-GJS-500-7

520 (75)

340 (49)

8

190

EN-GJS-500-3

620 (90)

400 (58)

4

200

This information has been sourced, reviewed and adapted from materials provided by Fonderie Saguenay.

For more information on this source, please visit Fonderie Saguenay.

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