What does SG 500/7 mean?

Spheroidal graphite (ductile) iron with at least 500 MPa tensile strength and 7% elongation, under IS 1865.

What is the difference between SG iron and grey cast iron?

In SG iron the graphite forms round nodules instead of flakes, which makes it much stronger and able to bend before breaking. Grey iron is cheaper and damps vibration better but is brittle.

Is SG 500/7 the same as GGG50?

Yes, they are equivalent grades; GGG50 is the old German name, now EN-GJS-500-7.

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SG iron 500/7

Also called: SG 500/7, ductile iron, spheroidal graphite iron, GGG50, EN-GJS-500-7, IS 1865, nodular iron

SG iron 500/7 is a grade of ductile (spheroidal graphite) cast iron: 500 MPa minimum tensile strength and 7% minimum elongation. Its round graphite nodules make it far stronger and tougher than grey iron, so it is used for valve bodies, gear blanks, crankshafts and automotive parts.

Quick facts

Standard: IS 1865 (SG iron castings)
Tensile strength: 500 MPa minimum
0.2% proof strength: About 320 MPa minimum
Elongation: 7% minimum
Typical hardness: About 170–230 HB
Matrix: Ferritic-pearlitic

Common SG iron grades

Grade (IS 1865)	Tensile (min)	Elongation (min)	Closest European
SG 400/15	400 MPa	15%	EN-GJS-400-15
SG 450/10	450 MPa	10%	EN-GJS-450-10
SG 500/7	500 MPa	7%	EN-GJS-500-7 (GGG50)
SG 600/3	600 MPa	3%	EN-GJS-600-3
SG 700/2	700 MPa	2%	EN-GJS-700-2

Higher grades are stronger but less ductile. ASTM A536 80-55-06 is close to SG 500/7.

Typical uses

Valve and pump bodies
Gear blanks and hubs
Crankshafts and camshafts
Hydraulic cylinder parts and manifolds
Automotive suspension and steering parts
Pipe fittings

Working with it

Machines well, a little harder to cut than grey iron
Can be heat treated (for example austempered to ADI) for higher strength
Ask for the nodularity and test-bar results with the castings if the part is critical

Need parts made in SG iron 500/7?

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Related job work

Machines

Materials

FG 260 grey cast iron

Questions

What does SG 500/7 mean?: Spheroidal graphite (ductile) iron with at least 500 MPa tensile strength and 7% elongation, under IS 1865.
What is the difference between SG iron and grey cast iron?: In SG iron the graphite forms round nodules instead of flakes, which makes it much stronger and able to bend before breaking. Grey iron is cheaper and damps vibration better but is brittle.
Is SG 500/7 the same as GGG50?: Yes, they are equivalent grades; GGG50 is the old German name, now EN-GJS-500-7.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 8 October 2026.