In this paper, machinability of AISI 316 austenitic stainless steel was investigated using cryogenically treated and untreated high-speed steel (HSS) twist drills. Machinability of AISI 316 austenitic stainless steel was evaluated in terms of thrust force, tool life, surface roughness, and hole quality of the drilled holes. Experimental results showed from 14% to 218% improvements for treated tool lives. Thrust force, surface roughness, and hole quality are better with treated drills when compared with untreated drills. These improvements were mainly attributed to formation of fine and homogeneous carbide particles and transformation of retained austenite to martensite. Microhardness and microstructure observations verified these formations.

This study investigated the effects of shallow and deep cryogenic treatment on the microstructural and mechanical properties of Sverker 21 tool steel. After conventional heat treatment, shallow cryogenic treatment at −80 °C for 2, 12, and 24 h and deep cryogenic treatment at −180 °C for 2, 18, and 36 h were applied on the steel samples. After that, the samples were tempered at 200 °C for 2 h. As a result of these treatments, the steel samples’ hardness, toughness, and wear rate changes were determined, and their microstructural properties were investigated. As a result of the study, it was observed that the cryogenic treatment had positive effects on the mechanical and microstructural properties of Sverker 21 steel. Mechanical properties also improved with increasing holding time for both cryogenic treatment types. It has been found that the deep cryogenic treatment provides better mechanical properties compared to the shallow cryogenic treatment. The maximum hardness and wear resistance were obtained in the deep cryogenically treated sample for 36 h. Compared to the CHT sample, the hardness and impact energy of the DCT(36) sample increased by approximately 11.75% and 17.36%. An improvement of approximately 64% was observed in the wear rate.

This study evaluated the effects of cutting tool coating type and process parameters on flank wear and surface roughness in the turning of hardened 1.2343 hot work tool steel. Two different coated tungsten carbide cutting tools (CVD TiCN/Al ₂ O ₃ /TiN and PVD TiAlN/TiN), three different cutting speeds and three different feedrates were used for the experimental tests. Turning tests were designed based on the Taguchi method (L18). Experimental results demonstrated that the PVD TiAlN/TiN tool performed better under all cutting conditions. Analysis of variance results determined the feedrate, with an impact ratio of 82.61%, to be the parameter with the most impact on surface roughness, while flank wear was most affected by the cutting tool, with 89.12%.