Also some ductile iron are also used in manufacturing engine blocks.

SAE AMS 5313C:

mechanical properties: [alloying: understanding the basics , by joseph R devis.]

Grade or class

Hardness HB(a)

Tensile strength min(b) MPa

Yield strength min(b)

MPa

Elongtion in 50 mm(2in),%(b)

Class A

190 max

414

310

15

Gray cast iron has excellent damping capacity, good wear and temperature resistance, is easily machinable, and is inexpensive to produce. However, gray cast irons are relatively weak and are prone to fracture and deformation.

Although cast iron meets most of these requirements, it has a low thermal conductivity and is comparatively heavier. Due to these limitations, light aluminium alloys have been used as alternative cylinder-block materials for petrol engines. Cylinder liners are optional with cast-iron blocks; but are more essential with the relatively soft light aluminum alloy blocks, as they cannot directly withstand wear resistance. Because of the lower strength of the aluminum alloys, the blocks are cast with thicker sections and additional support ribs, so that their weight becomes about half of the equivalent cast-iron blocks. Due to these problems, compacted graphite iron has recently begun to compete with gray cast iron as the choice material to produce diesel engine blocks.

COMPACTED GRAPHITE CAST IRON:

Compacted graphite cast iron (CGI), which was accidentally discovered while trying to

produce ductile cast iron, possesses higher tensile strength and elastic modulus than gray cast