Evaluation of Structural Powder Steel Properties after High-Temperature Thermomechanical Treatment and Finish Turning

Abstract

High-temperature thermo-mechanical processing (HTTMP) is a combination of plastic deformation and heat treatment operations. Such action makes it possible to increase metal mechanical properties resulting from both mechanical strengthening and heat treatment. As a result, it is possible to achieve high complex of operating characteristics of different types of steel and other alloys. However, there is a lack of information on the applicability of HTTMP of powder steel. These types of steel are very effective substitutes for traditional structural steel but are characterized by poor mechanical properties. This study considers the possibility of using HTTMP for powder steel frame additionally infiltrated by bronze with MoS 2 addition to increase mechanical properties of the materials studied. Steel infiltrated, infiltrated and then hardened, infiltrated and then HTTMP treated with strain rates of 30, 50 and 70% were compared. The microstructural properties and hardness of the materials before machining were studied as well as the cutting forces and surface topography of those materials after turning with AH8015 carbide inserts. Cutting forces tests were realized with v c = 157 m/min, f = 0.25 mm/rev and a p = 0.25 mm. Surface topography tests were carried out with v c = 157 m/min, f = 0.25 mm/rev and a p = 0.25 mm. Constant cutting parameters were used to eliminate the effects of rest factors. It was found that the lowest cutting forces (F c , F p and F f ), surface roughness parameters (Sa and Sq) and small areas with single high peaks on the machined surface were obtained for infiltrated powder steel with subsequent HTTMP machining under 50% strain rate.