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Investigating the Effects of Conventional and Non-Conventional Welding Techniques on Microstructure and Residual Stress in Creep-Resistant Steels

Gür, Cemil Hakan
Tirkeş, Süha
Aslam, Muhammad Junaid
The use of creep-resistant steels for the fabrication of components in boiler tubes and fittings in power plants due to their high temperature strength properties has increased in recent years. However, experience with the welded creep resistant steel components currently in service as well as the results of creep tests indicate reduced creep rupture strength of weldments compared to the base material. Besides, it is known that the magnitude and distribution of a residual stress play a vital role in the integrity and reliability of a welded structure. For instance, a tensile residual stress combined with the stresses due to service loads can induce catastrophic effects on a fatigue behavior, corrosion properties and a brittle fracture. Also, the initiation and growth of defects are both influenced considerably by the presence of residual stresses. The aim of this research is to optimize the welding procedure for better service performance of creep-resistant steels in power plants by comparing the effects of conventional (gas metal arc welding) and non-conventional (hybrid plasma arc welding) techniques on the microstructure and residual stress state.