Technological processes of machining lead to plastically deformation of workpieces. Therefore it is needful to know influence of machining to machined material. The area of plastically deformation caused by friction of tool to machined surface was analysed. Local strain in structure was estimated by measurement of deformation of grains on metallographic cut using stereology. Local plastic deformation in deformation zone around the surface of drilled holes, local plastic deformation in deformation zone near the surface of milled workpiece and local plastic deformation near the surface of turned workpiece were investigated. The working piece was bulk from carbon steel CK45 (1.0503). Local plastic deformation was observed in case of drilling and turning, in case of milling no deformation of surface was present.