CREEP CONTINUUM DAMAGE CONSTITUTIVE-EQUATIONS FOR THE BASE, WELD AND HEAT-AFFECTED ZONE MATERIALS OF A SERVICE-AGED 1 2CR1/2MO1/4V-21/4CR1MO MULTIPASS WELD AT 640-DEGREES-C/

Creep continuum damage constitutive equations have been determined for the base, weld and heat-affected zone materials of a service-aged 1/2 Cr 1/2Mo1/4V:2 1/4Cr1Mo multipass weld at 640 degrees C. The base and weld material properties were determined from uniaxial creep and notch ed bar creep rupture test results. The properties of the heat-affected zone material were determined from impression creep tests, waisted cr oss-weld specimen tests and notched cross-weld specimen tests. At the test temperature of 640 degrees C, surface oxidation occurs. For the u niaxial creep and notched bar creep tests, this oxidation was consider ed not too significant. However, for the low-load impression creep tes ts, the oxidation depth was comparable to the indentation depth.