Deep cryogenic treatment of carbide tool and its cutting performances in hard milling of AISI H13 steel

Microstructure and mechanical properties of cutting tool have significant effect on tool wear, especially in hard machining process. As an effective non-destructive modification technology, cryogenic treatment is widely used for carbide tools in order to change its microstructure and phase constituent which reflects the change of hardness, wear resistance and plasticity in macroscale. In this paper, an orthogonal experiment was designed to investigate the effect of deep cryogenic treatment parameters (cryogenic temperature, cooling rate, soaking time, and tempering temperature) on microstructure and mechanical properties of carbide tool with Ti (N, C)-Al2O3 coatings as well as its cutting performances in hard milling of AISI H13 steel. First, the microstructure of carbide tool was observed by means of scanning electric microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The experimental results show that WC grains were refined and large amounts of dispersive carbide was precipitate out. Secondly, the variation of hardness was measured through Vickers tester and the surface microhardness was improved evidently after cryogenic treatment. Range analysis was employed and the analysis results reveal that temperature has the most significant influence on hardness followed by cooling rate, holding time and tempering temperature. Finally, hard milling experiments were carried out and the experimental results indicate that the flank wear VB decreased under same material removal volume and tool wear resistance is strengthened. The research can provide an instruction for improving mechanical and physical properties of cutting tools to increase tool life. (C) 2018 The Authors. Published by Elsevier Ltd.