Mechanical and electrochemical behaviors of butt-welded high temperature steel pipes

Autor: Morteza Daavari, Seyed Ali Sadough Vanini, Eskandar Fereiduni, Mohsen Hosseinpour Rokni
Rok vydání: 2016
Předmět:
Zdroj: Engineering Failure Analysis. 62:287-299
ISSN: 1350-6307
DOI: 10.1016/j.engfailanal.2016.01.010
Popis: In this study, fatigue, corrosion fatigue and electrochemical behaviors of butt-welded A106-B steel pipes were investigated. These pipes were subjected to mechanical and thermal cyclic stresses due to the internal pressure fluctuations and cooling–heating cycles. Residual stress measurements were carried out for three different depths through the thickness and were correlated to the microstructural observations and microhardness measurements. Results showed that the maximum tensile residual stresses existed at the boundary of weld metal and base metal because of the contraction–expansion effects resulting from phase transformations and cooling rate differences. Fatigue fractures occurred at regions experiencing the maximum tensile residual stress under fatigue and corrosion fatigue tests. The change in frequency had no significant effect on the atmospheric fatigue. However, lower frequencies were associated with shorter corrosion fatigue lives in the corrosive environment containing Cl − ions. The corrosion potentials for different regions of weld zone were close to each other while corrosion current density and corrosion rate varied significantly.
Databáze: OpenAIRE