Effects of cryogenic treatment types on the performance of coated tungsten tools in the turning of AISI H11 steel

Abstract

This study investigated the effects of the cryogenic treatment on cutting tool performance in the turning of AISI H11 steel. In the experiments, TiCN/Al2O3/TiN-coated tungsten carbide tools were used. Shallow cryogenic treatment was applied for 6 h at −80 °C (SCT6), deep cryogenic treatment at −196 °C for 6 h (DCT6), and deep cryogenic treatment at −196 °C for 24 h (DCT24). Turning tests were conducted at three cutting speeds (200, 240, and 280 m/min), three feed rates (0.15, 0.18 and 0.21 mm/rev), and a 0.6-mm depth of cut under dry cutting conditions. Experimental results showed that the cryogenic treatment increased the abrasion resistance of the cutting tool. The best cutting tool wear and surface roughness performance was obtained with the DCT24 tool. As a result of the tool life test, DCT24 tool wore 14.5% less than U tool. In terms of surface roughness, DCT24 tool improved up to 16.5% compared to the U tool. Moreover, it was determined that the cryogenic treatment provided an increase in the hardness of the cutting tools. The highest hardness increase also occurred in the DCT24 tool (10.87%). In addition, cryogenic treatment types were optimized for flank wear and surface roughness using the Taguchi method, and the effect levels of the cutting tools and cutting parameters were determined via analysis of variance. According to ANOVA results, for flank wear, the parameter having the most effect was the cutting speed, with an ratio of 56.811%, while for surface roughness it was the feed rate, with 95.827%.

Keywords

• Shallow/deep cryogenic treatment
• AISI H11
• Microhardness
• Tool wear
• Surface roughness