Residual Stress in High-Pressure Water Jet Assisted Turning of Austenitic Stainless Steel

In this paper, the effect of a high pressure water jet, directed into the tool chip interface, on surface residual stresses and chip shape, in face turning of AISI 316L stainless steel has been investigated. Tests have been carried out with a standard cutting tool. This tool is not specifically meant for the machining of this type of material. The cutting speeds used were 80 m/min and 150 m/min, with a constant feed rate of 0.1 mm/rev and a constant cutting depth of 0.1 mm. Three jet pressures were used: 20, 50 and 80 MPa. Residual stress profiles have been analysed using the X-ray diffraction method in both longitudinal and transversal directions. The results show that by using a high pressure jet directed into the tool-chip interface, it is possible to create a well fragmented chip in contrast to the continuous chip formed using dry turning. It is also possible to control the chip shape and increase tool life. When the jet pressure is increased the residual stress at the surface decreases however it is increased by an increase in cutting speed. It can be concluded that surface residual stresses can be reduced by the introduction of a high pressure water jet. A reduction in the residual stress value by about 20 to 40 % can be observed when using high pressure water jet assisted turning compared to dry turning. Also, it has been observed that the jet pressure does not have a great influence on the depth affected by residual stress and by hardening.