By increasing the Silicon and Molybdenum content of SG Iron, the heat resistance and strength at high temperatures is increased.

Physical properties depend on temperatures; typical values are detailed in the table below:

C=3.2-3.8%, Si=4.0-5.0%, S < 0.02%, Mg=0.03-0.07%, Mo=0.5-1.5%

Temperature oC Tensile Strength N/mm2 0.2% Proof Stress N/mm2 Modulus of Elasticity N/m x 104 Hardness BHN
23 550 480 14.8 (200-240)
300 480 395 14  
500 350 270 12  
800 50 30 2.5  

The main application for SiMo is in Automotive Exhaust and Turbocharger Systems, but it is suitable for any high temperature application where both strength and ductility are required.

Machineability is similar to that of EN-GJS-500-7.

Guideline Figures for Maximum Manifold and Exhaust Gas Temperatures

Material Grade Max. Manifold Temperature °C Max. Exhaust Gas Temperature °C
EN-GJS-400-15 700 770
EN-GJS-SiMo (0.5% Mo) 750 820
EN-GJS-SiMo (1.0% Mo) 780 820
EN-GJS-SiMoNi 795 835
Ni Resist D-5S 870 950