RESIDUAL-STRESS MEASUREMENT IN FERRITIC STEEL TUBE WELDS USING X-RAY-DIFFRACTION

The X-ray diffraction (XRD) technique has been used to measure the res idual stressed before and after post-weld heat treatment in autogenous butt weld joints in 2.25Cr-1Mo steel tubes. The tubes are used in the steam generator assemblies of fast breeder reactors. Measurement data show that the stress in the weld centre is similar to 150 MPa maximum . The stress distribution around the weld centre is asymmetrical with larger amounts of compressive stress on the sine of the tube sheet blo ck. The stress becomes compressive beyond similar to 5 mm from the wel d centre reaching values of similar to 200 MPa and more. Post-weld hea t treatment (PWHT) at 923 K for 30 min removes most of the residual st resses and PWHT at 988 K for 2.5 h removes all the residual stresses i n the weld regions.