Following book is about the possibilities of improvement of grey cast iron properties. This cast alloy of iron is widely used in many branches as a machine part where high tensile strength and impact strength is not demand. Presence of graphite in grey cast iron causes various beneficial properties as reduction of vibrations, improvement the machinability and the sliding properties lowering friction. Grey cast iron are charateried by lower density than that of steel, better casting properties than cast steel.
Improvement of its surface layer properties make possibilities of spreading its application, and even using it instead of more expensive materials.
One of method that can change surface layer properties greatly is laser heat treatment, and particularly laser alloying. The specificity of this treatment consist on three aspect.
The laser beam power focus on small area of treated surface causes high values of its density that can make radical changes in the surface layer like transformation of the alloy into a liquid state. Because of high laser beam velocities relative to the treated surface, the time of heating is very short, so this liquid alloy is immediately chilled. This cause rapid solidification, grain refining and non-equilibrium phases formation.
The second one is possibilities the addition of alloy element(s) or substances in to the liquid state during remelting. It is possible to implement a large amount of elements in various proportions, and even those elements with difficult solubility in the solid state.
The third one is that, the laser treatment is dedicated to only selected areas of machine parts that are the most exposed to damage by wear as a result of friction, corrosion or high temperatures. Therefore, the costs of usually expensive alloying elements can be reduced.
The use of such a specific surface treatment of grey cast irons may provide new possibilities for their application.
In the first chapter, except of short characterization of grey cast iron, laser alloying with chosen alloying substances has been presented.
The second chapter contain comparative preliminary research consisting in evaluating the surface layers of grey cast iron after laser alloying with various alloying substances in the same conditions.
In the third chapter application aspect of laser alloying has been presented. Laser alloying was implemented to the one of machine part, that is exposed to intensive abrasive wear.
The last chapter concludes performed analysis.
