Abstract
For the X-ray measurement of the residual stress of hardened steel, as a consequence of line broadening, Koistinen proposed the necessity of using the correction factors such as the Lorentzpolarization factor and the absorption factor.
Examination of these correction factors was made, using the specimens freed from residual stress.
Comparison between strain gage measurement and X-ray measurement of applied stresses was also made. Methods of making the stress free specimens were:
(1) Hot bath quenching (to minimize transformation stress)
(2) Thinning of a massive plate by chemical polishing (to relieve residual stress)
(3) Magnetic separation of grinding chips of hardened steel.
As a result of experiments for stress free state, raw data showed compressive strain, while the data corrected for background and LPA showed zero and somewhat tensile strain respectively.
Under loading conditions, the strain measured by X-ray, regardless of correction factors, corresponded to the applied stress within the error of 10kg/mm2. As a consequence, for measuring residual stress of hardened steel, it is enough to make merely the background correction, using (1+ν)/E=5.47×10-5mm2/kg
