Residual stress measurement in worked and heat treated steel by X-ray diffractometry

Investigations were made for residual stress measurement by X-ray diffractometry in the 1.14% C, 0.46% Mn, 0.16% Si, 0.11% S and 0.04% P steel samples subjected to inhomogeneous plastic deformation (cold upsetting in the range 7.7–21%), thermal gradient (quenching from 630 °C) and phase transformation (quenching from 850 °C), respectively. The results indicated that compressive residual stress at the surface increased in the samples with increasing deformation acquiring values in the range, −269.5 MPa to −374.7 MPa. In the samples quenched from 630 °C, the thermal stresses acquired increasing values in the range −83.9 MPa (compressive) to −188.1 MPa (compressive) with increased cooling rate. In the samples quenched from 850 °C, volume increase on account of austenite to martensite phase transformation ultimately dominated the thermal contraction resulting in residual stress at the surface from −329.3 MPa (compressive) to +61.7 MPa (tensile).