Optimization of plasma–powder surfacing parameters for the restoration of marine propeller shafts using computer modeling

Abstract

The article presents a comprehensive approach to studying the plasma-powder surfacing (PPS) process aimed at restoring the surfaces of marine shafts that experience intensive wear under operating conditions. The proposed method combines a regression–correlation mathematical model developed in the authors’ previous works with three-dimensional computational modeling of the thermal and mechanical processes accompanying the surfacing operation. The study examines the influence of key technological parameters ‒ welding current, arc voltage, surfacing speed, and plasma torch inclination angle ‒ on the formation of temperature fields, residual stresses, and the fatigue endurance of the deposited layer. For numerical analysis, a 3D model of a fragment of a marine shaft with a diameter of 200 mm and a length of 150 mm was constructed, including a deposited layer 10 mm wide and 3,5 mm high. Thermal processes were simulated using a moving concentrated heat source that reproduces real PPS operating conditions. Based on the finite element method, spatial temperature distributions and the stress–strain state in the surfacing zone were determined. The obtained results made it possible to trace the changes in T_max and σ_max depending on the process parameters and to identify trends that govern the quality of the restored layer. The proposed integrated model enables not only the evaluation of metal behavior during surfacing but also the optimization of PPS parameters according to criteria of minimizing residual stresses and increasing fatigue endurance. An optimal range of technological parameters has been established, ensuring the most favorable thermome-chanical state of the surface. The results of the study can be applied in developing technological guidelines for the restoration of marine shafts and other critical components of ship machinery and mechanisms.