Effect of deep cryogenic treatment on microstructure, mechanical properties and machining performances of coated carbide tool

Abstract

Deep cryogenic treatment (DCT) has been acknowledged as an approach to modify metallic materials properties to enhance their performance. The effects of deep cryogenic treatment parameters (cryogenic temperature, cooling rate, soaking time and tempering temperature) on microstructure, mechanical properties and machining performance of Ti (N, C)–Al2O3-coated cemented carbide insert have been comprehensively investigated in this paper. First, microstructure examination results show that a decarburization phase was detected and the WC particles were refined after deep cryogenic treatment. Secondly, the hardness of the WC–Co substrate and the wear resistance of the coatings after DCT were elevated. In addition, the transformation from α-Co to e-Co was observed, which is highly dependent on cryogenic temperature and soaking time. Finally, dry milling experiments were carried out and the results indicated that the tool wear resistance was improved and the experimentally measured cutting forces had lower values using cryogenically treated insert, which can be attributed to the dissolution of Co into WC yielding microplastic deformation as well as the enhanced wear resistance. This research can provide guidance for optimizing DCT parameters of coated carbide insert to acquire desired mechanical properties and improve cutting performance.