Modeling of the temperature field in the chip and in the tool in high-speed machining of a carbon steel: effect of pearlite to austenite phase transition in AISI 1075

Abstract

A one-dimensional transient finite-difference model for the temperature distribution in orthogonal metal cutting, which was originally developed by Boothroyd, and then improved upon by Tlusty, is used to calculate the temperature field in the chip and in the tool in orthogonal cutting of AISI 1075 steel. In a series of compression tests using the NIST pulse-heated Kolsky bar, a phase transformation from pearlite to austenite was observed to take place within a few seconds near the eutectoid temperature (723 ºC) of the material. At temperatures above the transformation temperature in this material, which had been heat treated so that it had uniform pearlitic microstructure prior to testing, a large decrease in flow stress of approximately 50 % was observed. It is shown how the predicted peak temperature along the chip-tool interface on the rake face decreases when this decrease in material strength is incorporated into a Johnson-Cook constitutive response model for the material.

Mini symposium on cutting and machining: 25 years of ESAFORM activity

“…However, questions still remain regarding the relevance of the heating and deformation rates applied in these tests compared to those existing in metal cutting. Burns et al (2010) developed to this end a pulse heated Kolsky bar set-up able to run compression tests at heating rates of up to 6000 ºC s − 1 and strain rates up to the order of 10 4 s − 1 . Applied on an AISI 1075 steel, they questioned the potential phase transformation which could occur during the compression tests but which are most probably not taking place in a true cutting configuration.…”