The speed influence of solidification and cooling on the microstructure and the mechanic properties of the FGL200 cast iron during the use of various filling materials in mask moulding.

Résumé

The microstructure and in particular the hardness of the cast iron FGL200 used in the process of mask moulding for the manufacture of the cylinder head for diesel engine depend mainly on the speed of the solidification and cooling. The successive use of siliceous sand, crushed stone and the soaked cast iron shot, as filling materials revealed an identical microstructure for the three filling materials, being composed of graphite rosette with a normal distribution in a ferritic matrix, only in the case of the cast iron shot, the graphite rosette are thicker and longer and the ferrite quantity is less important, which explains the rise in hardness in addition to the fact the thermal analysis showed speed of higher solidification and cooling relative to for the last filling materials. These results once again confirm the advantage of use of the cast iron shot as a filling material in this technology.

Key words : mask moulding-solidification-graphite lamellar-ferrite