Effect of turning parameters on surface layer features of 17−4 PH stainless steel under MQCL environment
摘要
This article evaluated the effect of cutting speed (vc), feed rate (f), and depth of cut (ap) on the SL indicators of precipitation-hardened 17 − 4 PH stainless steel (SS) after turning under minimum quantity cooling lubrication (MQCL) environment. Surface topography, first- and second-order residual stresses (RS), parameters of the thin crystalline structure, micro-hardness and micro-structure were analyzed. It was found that for low and high ap, with f = 0.1–0.14 mm/rev and vc = 100–120 m/min, a decrease in the surface roughness, dislocation density and a simultaneous increase in the average size of coherent scattering regions were obtained. Depending on the turning parameters, plastic deformation, high ridges and built-up edge (BUE) residues were observed on the turned surfaces. For low ap, an increase in second-order RS was observed at f = 0.1–0.14 mm/rev and vc = 100–120 m/min, whereas its decrease at f = 0.28–0.3 mm/rev and vc = 280–300 m/min. For high ap, the trend was the opposite. For low ap, a decrease in first-order RS was achieved in the range of f = 0.1–0.14 mm/rev and vc = 280–300 m/min and for high ap - at f = 0.1–0.14 mm/rev and the investigated vc range. The SL micro-structure revealed plastic deformation zones and a textured structure. The research confirmed the possibility of controlling SL condition indicators by changing turning parameters in an MQCL environment and thus, influencing the performance properties of products made from hardened SS.