Elkem Chart for Graphite Structuresin Cast Iron

GRAPHITE STRUCTURES IN CAST IRONS
GRAPHITE DISTRIBUTION IN GREY CAST IRON

GRAPHITE FORMS
Diagrammatic representations of the standard graphite forms in cast irons

TYPE A
Random flake graphite in a uniform distribution

Form

I

II

III

TYPE B
Rosette flake graphite

Form

IV

V

VI

GRAPHITE SIZES IN GREY CAST IRON
Diagrammatic representations of the standard flake graphite sizes in grey cast iron at
x100 magnification (Form I Distribution A)

TYPE C
Kish graphite
(hyper-eutectic compositions)

Largest Flakes

1
100mm or more

2
50 - 100mm

3
25 - 50mm

4
12 - 25mm

TYPE D
Undercooled flake graphite

Largest Flakes

TYPE E

5
6 - 12mm

6
3 - 6mm

7
1.5 - 3mm

8
less than 1.5mm

Interdendritic flake graphite
(hypo-eutectic compositions)

GRAPHITE SIZES IN DUCTILE IRON

Diagrammatic representations of the standard graphite nodule sizes in ductile iron at x100 magnification(Form VI)

SOME ABNORMAL GRAPHITE FORMS IN DUCTILE IRON

Largest Nodules

3
25 - 50mm

4
12 - 25mm

5
6 - 12mm

EXPLODED GRAPHITE
Caused by high purity charge materials and excess rare earth additions in high carbon equivalent irons or in thicker section castings

Largest Nodules

6
3 - 6mm

7
1.5 - 3mm

8
less than 1.5mm

CHUNKY GRAPHITE
Caused by high purity charge materials and excess rare earth additions in large section castings
or at high carbon equivalent

INOCULANTS

Elkem manufactures and markets a series of high quality inoculants to treat cast iron and ensure the production of the ideal graphite form, distribution and freedom from chill (cementite).

Inoculant

Active Elements Advantages and Uses

Superseed® 75/50 Si, Sr

Low Al content. Low eutectic cell count through lower addition rates. High chill reduction.

Foundrisil®/Barinoc® Si, Ba, Ca, (Al) High chill reduction. Resistance to fading. Used in all cast irons.

Ultraseed®

Si, Ca, Ce, (Al,S,O) High nodule count. Improved nodularity. Helps to prevent micro-shrinkage. Reactivates "dead" irons.

Reseed®

Si, Ca, Ce, (Al) High nodule count. Improved nodularity. Controls tramp elements in ductile irons. Low S grey iron.

All inoculants are available in sizes suitable for ladle or in-stream additions. Other inoculants for specialist applications are available.

SPIKY GRAPHITE
Caused by small amounts of tramp elements, e.g. lead, bismuth, antimony and titanium, in the absence of cerium

NODULARISERS

Elkem manufactures and markets a range of high quality nodularising alloys to produce ductile and compacted graphite cast irons. They contain balanced ratios of the active elements to control reactivity, minimise slag and neutralise tramp elements.

Product Elmag®

Active Elements Si, Mg, Ca, Rare Earths

Remag® Lamet™ CompactMag™

Si, Mg, Ca, Rare Earths Si, Mg, Ca, La Si,Mg, Ca, Rare Earths

Advantages and Uses Magnesium contents from 4 to 10%. Calcium from 0.2 to 3.5%. Rare Earths from 0.1 to 3%. Allows the choice of the ideal alloy for all foundry conditions. High RE, low Mg alloy for low reactivity. Suited to thin section ductile iron castings.
Alloy for in-the-mould treatment of ductile iron. Helps to prevent shrinkage.
Highly effective alloy for the production of compacted graphite irons with reduced section sensitivity and wide production window.

Description of a structure should follow the convention Form : Distribution : Size, e.g. Type IA4 for a grey cast iron Type VI5 for a ductile iron
Revised September 2004 © Copyright Elkem ASA

Please refer to your local Elkem representative for further information on the range of products available for grey, compacted and ductile irons.

Barinoc®, Elmag®, Foundrisil®, Remag®, Reseed®, Superseed® and Ultraseed® are registered trademarks of Elkem ASA. CompactMag™ and Lamet™ are trademarks of Elkem ASA.

The graphite form, distribution and size diagrams are taken from the international standard EN ISO 945:1994 by kind permission of the British Standards Institution, London. W4 4AL.
Photographs of the graphite structures are reproduced by kind permission of Elkem Research, Kristiansand, Norway and the Castings Development Centre, Alvechurch. Birmingham. B48 7QB.

www.foundry.elkem.com

Elkem ASA, Foundry Products Division, Hoffsveien 65B, PO Box 5211 Majorstua, N-0303 Oslo, Norway. Tel: +47 22 45 01 00 Fax: +47 22 45 01 52