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Discovering the Superior Performance and Applications of Ductile Iron in SAE J434

Discovering the Superior Performance and Applications of Ductile Iron in SAE J434

May 9,2024
Ductile Iron, also known as spheroidal or nodular iron, is described as cast iron in which the graphite is present as spheroids, instead of flakes as in gray iron or temper carbon nodules as in malleable iron. Ductile iron is most popular metal material.

Reference Casting Standards: 
SAE J434: Automotive Ductile (Nodular) Iron Castings

Ductile Iron castings can be produced in Casting Quality 

 Sand Casting 
 Shell Casting 
 Lost Form Casting

Ductile iron standard grades in SAE J434

SAE J434 Ductile Iron Heat treatment requirement: 
Generally the heat treatment of castings and specimens in SAE J434 in order to meet the hardness or 
mechanical property requirements is permissible only with the express approval of the casting purchaser. 

But the typical microstructures of the grade of ductile iron as follows (for reference only): 
D400(D4018) is a ferritic ductile iron most commonly made by annealing. 
D450 (D4512) is ferritic ductile iron supplied either as cast or heat treated. 
D500 (D5006) is ferritic-pearlite ductile iron supplied either as cast or heat treated. 
D550 (D5504) is pearlitic-ferritic ductile iron supplied either as cast or heat treated. 
D700 (D7003) is either as cast or qir quenched to a specified hardness range. 
D800 is either as cast or air or liquid quenched and tempered to a specified hardness range. 
DQ&T is liquid quenched and tempered grade. 

SAE J434 Microstructure: 

The graphite component of the microstructure shall consist of at least 80% spheroidal graphite conforming 
to types I and II (per ASTM A247)
The matrix microstructure shall consist of ferrite, ferrite and pearlite, pearlite, tempered pearlite, or tempered martensite, or a combination of those.
D400 Typical Matrix Microstructures
D450 Typical Matrix Microstructures
D500 Typical Matrix Microstructures
D550 Typical Matrix Microstructures
D700 Typical Matrix Microstructures
D800 Typical Matrix Microstructures
Chemical Composition in SAE J434 ( for information only): The typical chemical composition of 
unalloyed iron generally confirms to following range. The spheroidal graphite structure is produced by 
alloying the molten iron with small amounts of one or more elements such as magnesium or cerium. The 
matrix microstructure may be controlled by addition of other alloying elements, such as: copper, tin, nickel, 
chromium and molybdenum. 

Carbon: 3.20-4.10% 
Silicon: 1.80-3.00% 
Manganese: 0.10-1.00% 
Phosphorus: 0.050% max 
Sulfur: 0.035% max 
Magnesium: 0.025-0.060% 

Typical un-notched Charpy impact energy properties are from low residual element content iron, 
impact values are affected by microstructure and section size:
TYPICAL IMPACT VALUE(For information only)
SAE J434 D400(D4018)
SAE J434 D450(D4512)
SAE J434 D500(D5006)
SAE J434 D550(D5504)
SAE J434 D400(D4018)
SAE J434 Ductile Iron Typical Casting Application 
Machinery, valve, truck, railway, gearbox, flywheels etc.
D400 (D4018 is used in moderately stressed parts 
requiring high ductility and good machinability. 
D450 (D4512) and D500 (D5006) are used for 
moderately stressed parts where machinability is less 
D550 (D5504) is used for more highly stressed parts. 
D700 (D7003) and D800 are used where high strength 
and/or improved wear resistance are required and where 
selective hardening is to be employed. 
DQ&T is used where the uniformity of a heat treated 
material is required to control the range of mechanical 
properties or machinability.

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