Mechanical properties of hardened layer under reversible surface plastic deformation

Abstract

The article presents the results of experimental studies to determine the influence of the parameters of reverse surface plastic deformation (RPD) on the mechanical properties of the surface layer of cylindrical parts made of carbon steel 45. To implement the proposed method of finishing and hardening processing, a device has been developed that provides reverse circular motion of the working tool. Using the HBRV-187.5 hardness tester, HMV-G21 microhardness tester and MET-2 microscope, the hardness of the surface layer, microhardness, grain structure and depth of the hardened layer of hardened parts were determined. Experimental studies have shown that after reverse SPD, the hardness of the surface layer increases by 9...15 % compared to the hardness of the original surface, and the microhardness increases by 1,6...1,8 times, which leads to a significant hardening of the surface layer. The depth of the hardened layer is 0.8...1.6 mm, and the degree of hardening is 55...80 %. According to the results of experimental studies and using the PyCharm computer program with the Python programming language, the optimal modes of hardening by reverse SPD were determined, providing both the maximum depth and the highest degree of hardening of the surface layer, which are formed under the following processing modes: longitudinal feed 0.08...0,10 mm/rev; workpiece rotation frequency 280...300 rpm; the value of the radial interference 0.28...0.30 mm; reverse speed RI 290...300 strokes/min; the initial installation angle of RI is 90° and the value of the angle of reverse rotation of RI is ±15°.