Experimental investigation of the effect of chip removal parameters on residual stresses at screw roots

In this study, the experimentally determination of the residual stresses which were resulted from threading, grooving and turning processes by means of chip removal, the comparison of residual stresses which generated with various turning processes and investigation of the effects of parameters in turning processes on residual stresses are aimed. For this purpose, various turning processes were carried out using different machining parameters on AISI 4140 and AISI 4340 steels and the effects of the processing parameters on residual stresses were investigated. Residual stresses were determined by layer removal method. Sequential removing of layers was carried out using electrochemical machining. The changes in residual stresses resulted from different turning processes were plotted with respect to the distances from the original surface. Limits of main residual stress obtained form the gradient of residual stresses plots were used for the investigation on the effect of the process parameters. As a result of this study, it is obtain that in chip removal the residual stresses were resulted from mechanical and thermal effects. Thus, it is observed that the tensile residual stresses were resulted form the parameters which increase the thermal effects and the compressive residual stresses were resulted from the parameters which increase the plastic deformation. It is also determined that the various cutting shapes in machining processes such as the threading, the grooving and the turning causes the different chip formations and these different chip formations have the most important effect on the residual stresses. Key Words : Residual stresses, metal cutting, steels, threading, grooving, turning