Experimental investigations of effect of tempering on residual stresses developed during the turning operation

Abstract

The Cos α method has emerges as new technique for measurement of the residual stresses using whole Debye-Scherrer ring recorded on two dimensional imaging plates (IPs) with the help of X-ray residual stress measurement system μ-X360 Ver. 2. 3. 0. 1. Considering with more accountability of the tempering treatment process for decreasing or eliminating the residual stresses, the effect of tempering is monitored experimentally. The main objectives of this paper is to predict the residual stresses distribution, and surface roughness of the machined samples (with and without tempered) on CNC lathe at the same process parameters (speed, feed and depth of cut) using tungsten carbide tool. Surface residual stresses of five turned specimen with and without tempered have been measured. The residual stress graphs, FWHM (full width at half maximum) graphs and Debye –scherrer rings, and surface roughness of all samples have been obtained and critically studied. The residual stress and surface roughness were found minimum in sample tempered at 450°C. The min and max peak values were found as 149 k and 175 k for samples tempered at 450°C and untempered respectively. The average surface roughness (Ra = 2.06, Rq = 10.4 and Rz = 2.45) and(Ra = 3.65,Rq = 16.9 and Rz = 4.27) were seen in sample tempered at 450°C and untempered respectively. The results obtained from the present experiment, literature review and the theoretical study validate the present work and method in strong confirmation and bear a good agreement among them.