The role of plastic deformation in the roughening of fracture surfaces is described. A model was developed based on elasticity theory supplemented with considerations of plastic deformations focusing on infinite two-dimensional materials. In the method of iterated conformal mappings one starts with a crack for which the conformal map from the exterior of the unit circle to the exterior of the crack was known. The method of iterated conformal mapping was used to make the growth step to coalesce the tip with the void.