OBRABOTKAMETALLOV Vol. 24 No. 1 2022 TECHNOLOGY The purpose of this work is to study the effect of the normal force during dry diamond burnishing with a spherical indenter on smoothing of turned surface microprofi le and on deformation hardening of the 03Cr16Ni15Mo3Ti1 austenitic steel surface layer. Research methodology The study of dry surface burnishing was performed on austenitic stainless steel 03Cr16Ni15Mo3Ti1 (C – 0.03 %; Cr – 16.64 %; Ni – 14.96 %; Mo – 2.77 %; Ti – 1.25 %; Si – 0.53 %; Mn – 0.38 %; Cu – 0.11 %; P – 0.03 %; S – 0.02 %; the rest – Fe). The experimental samples of the “disk” type with a diameter of 104 mm and a thickness of 19 mm were subjected to heat treatment – quenching from the temperature of 1,100 °C (exposure time of 1 hour) with cooling in water. After quenching at the Takisawa EX-310 turning and milling center, the fi nish turning of the sample end surface was performed with a WNMG080408 tool plate using a lubricating and cooling water-emulsion process medium (LCPM) at a cutting speed of 150 m/ min, a feed of 0.08 mm/rev and a cutting depth of 0.3 mm. After turning, the average surface roughness was Ra = 1.0 μm, and the microhardness was 311±10 HV 0.05 and 331±9 HV 0.2. Further, after turning, concentric ring sections with a width of 5 mm were burnished on the treated sample surface (Fig. 1). Burnishing was carried out with a tool able to adjust the burnishing force and to use a spherical indenter with a radius of 2 mm made of natural diamond without using LCPM (in air). The burnishing force varied according to the data of Table. The range of force variation from 100 to 200 N was selected in accordance with the study of burnishing AISI 316Ti analog steel, which was made by Maximov et al. [24]. In accordance with this study, the feed value fb = 0.025 mm/rev was taken. The choice of the indenter sliding speed (vs = 10 m/min) is justifi ed by the maximum permissible speed of dry burnishing the stainless high-chromium steel surface found in [25]. Exceeding the permissible sliding speed leads to a signifi cant increase in roughness and surface layer micro-fractures occurrence. a b Fig. 1. Burnishing of the sample surface on the turning-milling center (a) and annular sections (b), indicated by numbers according to the given burnishing force given in Table Parameters of dry diamond burnishing of ring sections Mode Burnishing force Fb, N Sliding speed vs m/min Feed rate fb, mm/rev 1 200 10 0.025 2 175 3 150 4 125 5 100
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