Mechanics of Grains Size and Orientation on the Machining of AISI S-7 Steel Grade Using Numerical Technique

Two-dimensional models namely homogeneous, uniformly distributed grains and non-uniformly distributed grains were developed for AISI S-7 steel grade metal, to investigate the effect of the grains size and orientation on the chip morphology and temperature rise during the orthogonal machining process. A Johnson-Cook model was used for the simulation study. The machining was done at a medium speed of 60 ms-1 and the depth of cut was maintained at 5 mm in all the above cases. Compared to other models, results showed that nonuniformly distributed grains develop alternate low and high shear bands and generate maximum temperature in the high shear band zone, which was found to be detrimental during the machining process compared to other models. Intergranular chip segmentation was observed in the case of uniformly distributed grains. For the same material, three different chip morphologies and temperature profiles were observed during the orthogonal machining process. Detailed discussion on the mechanics of machining of the above-said models was done that may be advantageous for material and tool design scientist.