Plastic deformation and critical condition for orthogonal machining two-layered materials with laser cladded Cr-Ni-based stainless steel onto AISI 1045

摘要

Laser cladding has been widely used to repair some high value-added parts for remanufacturing or sustainable production. Additional machining is necessary when the repaired parts require high precision and high quality. However, using conventional cutting theory to machine cladding workpiece is always a challenging work. The depth of cut in machining cladding workpiece is restricted in a shallow range and exhibits comparable to the thickness of cladding. It is meaningful to explore the critical conditions for orthogonal machining two-layered workpiece formed by laser cladding. The critical condition was defined as an initiation of plastic deformation in substrate while elastic deformation still occurring in the bottom of cladding. These different deformation mechanisms attributed to the inferior physical-mechanical characteristics of the substrate compared to the cladding. The stresses induced by machining can reach the cladding-substrate interface and result in a premature plastic deformation in substrate. As a result, discontinuous plastic deformation zones generated in both subsurface and sub-strate. For this reason, a coupled thermo-mechanical model was developed to predict the plastic deformation behaviors in subsurface and substrate materials. It was found that the ratio of uncut chip thickness to critical cladded thickness ranged from 0 to 0.678 with increase of uncut chip thickness. It meant that the thicker the cladding was, the more difficult it would be to induce a premature plastic deformation in the substrate. Lower cutting force but higher specific cutting energy was found under lower uncut chip thickness. Thinner cladding was not recommended for purpose of repairing. The results are expected to provide fundamentals to weigh pre-cladded thickness and cutting parameters in a post machining process for manufacturing sustainability. (C) 2017 Elsevier Ltd. All rights reserved.