High-temperature creep properties of fine grained heat-affected
zone in P92 weldment
zone in P92 weldment
(1. School of Power and Mechanics, Wuhan University, Wuhan 430072, China;
2. Dongfang Boiler Group Co. Ltd., Zigong 643001, China;
3. School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China)
2. Dongfang Boiler Group Co. Ltd., Zigong 643001, China;
3. School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China)
Abstract: The simulated fine grained heat-affected zone (FGHAZ) specimens for P92 welded joints were prepared by heat treatment, then the creep tests were carried out at 650 ℃ under the applied stress of 90−120 MPa to investigate high-temperature creep behavior of FGHAZ. The results show that the creep property of FGHAZ is much inferior to that of the base metal, which exhibits the much higher steady creep rate and shorter time to creep fracture. The power law equation can describe the steady creep rate dependence on applied stress, indicating that the stress exponent n of FGHAZ is distinguished between two regions with n=15.1 at high stresses (more than 100 MPa) and n=8.64 at lower stresses. Based on Monkman-Grant equation, the relationship between the secondary creep rate and time to rupture is obtained to evaluate the creep life of FGHAZ with the applied stress above 100 MPa.
Key words: resistant heat steel; welding; fine grained heat-affected zone(FGHAZ); creep