SA-02-4(107) Long term behavior of weldments of modern power plant steels(Life Assessment of Thermal Power Plant 2)

概要

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To increase efficiency of fossil fired power plants the process parameters, in particular the temperature, have been increased more and more. The newly developed 9 Cr and 10 Cr steels opened the way for this development. However, even if the parent material is well investigated and qualified, there is a strong need to know the long time behavior of weldments. Due to the different material properties in the different zones (heat affected zones, weld metal and base metal) stress redistribution, strain and damage behavior and location is much more complicated in weldments. Since there may occur a change in the fracture location (e. g. from weld metal to fine grained heat affected zone), the description of the long term behavior is much more difficult. To investigate the long term behavior a series of testing programs was started to investigate the long term behavior of similar welds of several header and piping materials namely 2 1/2 Cr and 9 Cr steels as well as a welded joint of an austenitic steel was investigated. Different welding techniques were used and the influence of the welding process and of the size of heat affected zones can be demonstrated.
2001-06-03