Selection of Geometric Parameters for Applying Strengthening Materials on the Friction Surface of Soil-Cutting Parts

Abstract—

The paper proposes using charts of the expected abrasive wear of the soil-cutting part’s friction surface that characterize the intensity of wear at various points on the friction surface moving in the soil environment [1]. The obtained abrasive wear charts provided characteristics of friction surfaces within the boundaries of a more or less expected abrasive wear intensity. Then, considering the different wear intensity of the friction surfaces at different points, hardening by the electrospark method was conducted using thermally pre-treated gray cast iron. The hardening consisted in quenching at temperatures of 750–1050°C, followed by water cooling, or annealing at a temperature of 900°C for 1 h. These pre-steps made it possible to form a wear-resistant layer in several passes, while the structure of the cast iron and the base metal did not change. The physicomechanical properties and structures of the hardened layer including gray cast iron were studied. After tempering at a temperature of 300°C, its hardness increased up to HRC 50–55 without subsequent formation of quenching cracks. The best gray cast iron heat treatment method is hardening at a temperature of 900°C followed by water cooling. The hardness of the deposited layer was higher (4800–5000 MPa) than that of the base metal (2300–2400 MPa), and no weakening of the base metal was observed. According to the results of testing the hardened products, heat-treated gray cast iron can be recommended for use as a strengthening material, since the coating thickness does not lead to changes in the initial geometric dimensions of a soil-cutting tool using differentiated surfacing based on abrasive wear charts. The practical application of the proposed hardening process is recommended for plowshares, cultivator shares, and ripper chisels, as well as for blades of soil-cultivating machines.