Some Studies on the Mechanism of Chip Formation during Machining of Chromium Manganese Austenitic Stainless Steel

Abstract

The mechanism of chip formation during machining depends on the type of (i) work material, (ii) tool material, (iii) machining parameters, (iv) tool geometry, etc. It is difficult to understand the mechanism of chip formation without performing experimentation. The present effort has been made to know the mechanism of chip formation during the machining of chromium–manganese austenitic stainless (AST) steel. The chip formation mechanism study for the present steel has been conducted by performing (i) mechanical testing for the work material, (ii) chip type study, (iii) optical microstructural study of the chip surface, and (iv) SEM observation for the chip surfaces. The present chromium–manganese stainless steel (austenitic) was dry-turned in a lathe. Three different experiments were conducted. The input process parameters were v (speed), f (feed), and DOC (depth of cut). The chip reduction coefficient (CRC) and the von Mises stress (VMS) were the output response parameters. The chip thicknesses were measured. The steel specimen was tested on the universal tensile testing machine. The chip reduction coefficients (CRCs) and the von Mises stress were experimentally determined. The undersides of the chips were examined under a light microscope. The chip’s top and bottom surfaces were viewed by scanning electron microscopy (SEM). The strain-induced martensite (SIM) formed at the chip surface (under) during the machining at the lower experimental parameters. The surface (underside) of the chip was influenced by the dynamic recrystallization (DRX) and the dynamic precipitation (DP) during the machining at the higher experimental parameters.

Keywords

• VMS
• machining
• dynamic recrystallization