The present work is dedicates to illustrate how a computer algorithm based on the generation of random numbers can be used successfully to simulate the grain structures presented in metallic materials. Here the random functions are programmed to create vertexes or nucleation nodes which can be growth, both algorithms are explained. Moreover the influence of these procedures on the grain size and morphology is also explained. After testing, the best fit was obtained simulating the two principal processes involved on grain formation (nucleation and growth) due to complex grain morphologies can be simulated creating columnar and equiaxed grains in two dimensional samples; and because this model allows to represent the grain formation dynamically as a function of time during solidification. © 2013 AIP Publishing LLC.