Influences of Micro Mechanical Property and Microstructure on Performance of Machining High Chromium White Cast Iron with cBN Tools

The variation of the micro mechanical properties, such as hardness and modulus, of the material is important potential factor influencing the machinability of the material. The presented paper is to study the influence of variation in micro hardness and microstructure of the materials on machining performance in terms of tool wear and tool life, cutting forces and surface quality. The work material is high chromium white cast iron and material of cutting tool is cBN. The variation of micro hardness were measured and analyzed by grid nano indentation approach. Volume fraction phases of the material were identified through Weibull mixture distribution from result of grid nano indentation. High chromium white cast irons were prepared with two groups of composition, lower carbon silicon and higher carbon silicon, in the state of as-cast and hardened condition. Results from the machining test indicate that the variation of micro hardness of the work materials show significant impacts on cutting tool wear, tool life, cutting forces and surface quality in the machining of these materials. The effect of micro mechanical properties needs to be taken into account in the modelling and predicting tool life and surface quality. In addition, the mechanism of interaction between the cBN tool and the high chromium white cast iron under the range of machining parameters was also addressed. Lastly, surface roughness measurements complemented the results and a qualitative relationship between the surface roughness generated during the machining and the materials is also laid out. (C) 2015 The Authors. Published by Elsevier B. V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).