Cast iron occupies one of the most important places among structural materials and is widely used in the manufacture of critical automotive parts.The article examines the possibility of processing gray cast iron by surface plastic deformation (SPD) and the study of its hardening depth in order to control the stress-strain state (SSS) of the surfaces of parts. Modeling is carried out, calculations are close to the real situation, a three-dimensional finite element model is used. The data obtained were analyzed by the least squares method (LSM), graphs were plotted.Also, based on the data obtained, it was found that the relationship between the degree of plastic deformation, the diameter of the indenter and the depth of work hardening is an equation that describes the surface. The carried out researches and the received dependence allow to increase the accuracy of forecasting of results of processing of PPD cast iron.

Keywords: grey iron,plastic deformation, bilinear deformation diagram, indentation depth, spherical indenter

The article examines the issue of calculating the depth of compression stresses when using a spherical indenter in order to increase the fatigue strength of steel parts. When the spherical indenter is pressed, elastic deformation of the surface first occurs, and then plastic one. The residual plastic deformation is expressed in the size of the print. The physicomechanical properties of the processed material are not taken into account, the process of pressing a spherical indenter into a steel sample in the ANSYS program is modeled by the final element analysis (FEA).A bilinear deformation diagram was fed, which is set in the program by the modulus of elasticity, yield strength and Poisson's ratio. At the next stage, a finite element grid was generated by using the Hex Dominant Method, which divided the model into elements in the form of hexahedra of various sizes. In the contact area, the size of the finite elements was 0.2 mm. The results of calculations of analytical and numerical methods for spherical indenter diameters of 4, 6, 8, 10 mm and various degrees of plastic deformation to determine the depth of compression stresses are presented, compared with known data, the error is calculated. A dependence is derived for a preliminary assessment of the occurrence of residual stresses depending on the diameter of the well after the indentation of the spherical indenter.

Keywords: spherical indenter, bilinear deformation diagram, plastic deformation, indentation depth, compression stress