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Grey Iron, commonly referred to as cast iron, is the most common of the cast iron alloys. Relatively cheap and easy to produce, grey iron finds its way into a number of engineering applications where strength and toughness are not the primary concern. The graphite present in grey iron exists in flake form, which is the primary physical difference when comparing grey, compacted graphite and ductile iron.

There are many different specifications governing the use and production of grey iron. At Matrix Iron Foundry, we produce grey iron in accordance with American Society of Testing and Materials (ASTM) A48, IS:210 1978 and BS EN 124:1994 as mentioned below.

ASTM A48 covers a class of cast irons that are intended for general use applications.

Grades of ASTM A48 Grey Iron Produced at Matrix Iron Foundry

ASTM A48 Grade Ultimate Tensile Strength (UTS) Brinell Hardness
Class 30 30,000 p.s.i 187-241
Class 35 35,000 p.s.i. 207-255
Class 40 40,000 p.s.i 217-269

*UTS values are minimums required by ASTM for an independently cast tensile test bar sample. Casting strength may be more or less depending on cast section thickness. Consult ASTM A48 or Matrix Iron Foundry for more information.

Desirable properties Common Applications
Excellent vibration dampening capability Brake drums, rotors and clutch components
High compressive strength Engine blocks, cylinder liners and heads
Good machinability Pulleys, sheaves and idler wheels
Exceptional heat transfer Gears
Low cost alternative to other engineering materials Hydraulic valves and components

Although A48 class 35 grey iron is a common material, and its application is very wide, but its total production volume is not large compared with other cast iron materials. It is because its hardness is difficult to control in production. If the brinell hardness is higher than 200, then it will bring difficulty to drill and milling machining. Lower than 200 will cause the grade reduced to class 30. Therefore, if ASTM A48 class 30 could meet your requirements of application, then it will be the better choice than class 35.

*SPECIFICATION SHEET FOR MECHANICAL & CHEMICAL COMPOSITION OF DIFF GRADES OF CAST IRON AS PER ASTM A48 GRADE: -

GRADE CLASS 30 CLASS 35 CLASS 40 CLASS 45 CLASS 50
% C 3.5 3.4 3.2 3.1 3.0
% SI 2 1.7 1.5 1.45 1.40
% MN 0.65 0.7 0.8 0.9 0.9
% P MAX 0.08 MAX 0.08 MAX 0.08 MAX 0.08 MAX 0.08
% S 0.12 0.12 0.12 0.12 0.12
Chromium = = = = 0.35
Molybdenum = = = = 0.30
BHN 170 - 241 187 - 241 187 - 255 196 - 255 196 - 269
TENSILE STRENGTH (PSI) 30,000 35,000 40,000 45,000 50,000
Minimum Wall Thickness 3/16" 3/8" 1/2" 5/8" 3/4"
* On a 1.2" ASTM A-48B Test Bar


*SPECIFICATION SHEET FOR MECHANICAL & CHEMICAL COMPOSITION OF DIFF GRADES OF CAST IRON AS PER IS:210: 1978 SI Unit -

GRADE FG 100 FG 150 FG 200 FG 260
% C 3.5 - 3.8 3.4 - 3.7 3.2 - 3.5 3.1 - 3.4
% SI 2.3 - 2.8 2.1 - 2.6 1.8 - 2.3 1.6 - 2.1
% MN 0.4 - 0.8 0.5 - 0.8 0.6 - 0.8 0.6 - 0.8
% P MAX 0.2 MAX 0.2 MAX 0.2 MAX 0.15
% S 0.06 - 0.15 0.06 - 0.15 0.06 - 0.15 0.06 - 0.12
C EQV. 4.2 - 4.6 4.0 - 4.3 3.8 - 4.1 3.6 - 3.9
BHN 120 - 140 130 - 150 140 - 170 170 - 220
TENSILE STRENGTH 12 kg/mm2 15 kg/mm2 20 kg/mm2 25 kg/mm2


BS EN 124:1994

The applicable British Standard in the UK for access covers and gully grates is BS EN 124:1994. This standard divides access covers and gully grates into a number of classes by static test load.

Group 1 minimum Class A15 Access covers and gratings capable of withstanding a 1.5 tonnes test load. For use in areas where only pedestrians have access.

Group 2 minimum Class B125 Access covers and gratings capable of withstanding a 12.5 tonnes test load. For use in car parks and pedestrian areas where only occasional vehicular access is likely.

Group 3 minimum Class C250 Access covers and gratings capable of withstanding a 25 tonnes test load. For use in car parks, forecourts, industrial sites and areas with slow moving traffic also in highway locations up to 500mm from the kerb and up to 200mm into the verge, excluding motorways.

Group 4 minimum Class D400 Access covers and gratings capable of withstanding a 40 tonnes test load. For use in areas where cars and lorries have access, including carriageways, hard shoulders and pedestrian areas.

Size(mm) Load Ability Approx Weight(KG)
300 A15 5
400 A15 7
500 B125 20
500 C250 23
600 B125 26
600 C250 37
600 D400 50
650 B125 40
650 C250 44
650 D400 56
700 A15 32
700 B125 41
700 C250 49
700 D400 70
750 B125 47
750 C250 69
750 D400 78
760 C250 66
760 D400 80
800 B125 66
800 C250 75
900 C250 76
900 D400 85


Surface Size Square & Rectangle Manhole Cover

Size(mm) Load Ability Approx Weight(KG)
230 * 280 B50 8
300 * 300 A15 7
300 * 300 B125 11.8
300 * 400 B125 14
300 * 500 B125 17
300 * 500 C250 19
400 * 400 A15 20
400 * 400 B50 21
400 * 600 A15 23
400 * 600 B125 26
450 * 900 A15 50
500 * 500 A15 20
500 * 500 B125 23
500 * 500 C250 33
500 * 700 A15 41
500 * 700 B125 55.6
500 * 700 C250 71.2
590 * 590 B125 39.5
600 * 600 A15 35
600 * 600 B125 54
600 * 600 C250 57
600 * 600 D400 75
600 * 900 A15 52
600 * 900 B125 59
600 * 900 C250 93
640 * 640 B125 58
640 * 640 C250 69
700 * 700 A15 55
700 * 700 B125 87
700 * 700 C250 90
700 * 900 B125 120
700 * 900 C250 138
700 * 1200 B125 130
700 * 1200 C250 145
760 * 760 B125 74
760 * 760 C250 76
790 * 1000 B125 80
790 * 1000 C250 138
800 * 800 A15 87
800 * 800 B125 105
800 * 800 C250 113
900 * 900 B125 93
900 * 900 C250 119
900 * 1100 B125 172
900 * 1100 C250 182
1000 * 1200 B125 185
1000 * 1200 C250 187



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