Abstract
The high temperature creep properties are very important as high temperature tubes, pipes, tanks and headers of the power plant are exposed by high temperature and pressure for a long time. Creep is considered as the most important deterioration mechanism of heat resistant components found in power plants. Therefore it is very essential to evaluate creep properties of HAZ (heat affected zone), which is considered to be very hazardous in weldment. In this paper, SP (small punch)-Creep test which is easy to get sample from field components is conducted to evaluate creep properties of the weldment microstructures. The test material that used in this paper was X20CrMoV121. The SPCreep test results showed that each microstructure has a different creep behavior. And each lethargy coefficient of weldment microstructure is evaluated by the relation among the temperature, load and the rupture time from SP-creep test. Also the life estimation equation was induced by using modified of power-law. The weldment microstructures for each 559℃ and 575℃ are estimated. The temperature is very similar to normal temperature of the domestic thermal power generation in working. And Sp-Creep tests were performed in argon atmosphere to avoid a variation of testing results caused by surface oxidant.
Keywords: CHHAZ, FGHAZ, ICHAZ, Lethergy Coefficient, Modified Power-law, SP-Creep Test, Weldment Microstrctures