One of the components of cast iron are graphite secretions, which can be observed during examination of the microstructure. Hardness around graphite nodules is different than hardness in other parts of material, which affects the overall homogenity and hardness of the material when using tempering processes. This problem can be minimized by using laser remelting technique, that melts a major part of the graphite and improves homogenity of material and it's hardness which is important factor of the material wear resistance.
In initial phase, we observed laser traces, that were made in pulse mode at different parameters. Then we observed microstructure, and set the parameters for optimal remelting. We measured remelting depth, width of the trace and hardness in different material zones. We also observed how use of absorber, in our case graphite, affects the remelting depth. After we decided which are our optimal parameters, we remelted surface of nodular cast iron at frequency of pulses 3 Hz. In the end we measured hardness in the molten, tempered and basic material zone.
|
