About this Abstract |
Meeting |
2021 AWS Professional Program
|
Symposium
|
2021 AWS Professional Program
|
Presentation Title |
Corrosion Resistance of Dissimilar Pipeline/Super Duplex Steel Welds |
Author(s) |
Waris Khan, Rahul Chhibber, Nitin Saini, Yajing Wang, Leijun Li |
On-Site Speaker (Planned) |
Waris Khan |
Abstract Scope |
Corrosion is one the most significant cause for the failure of material and joints in marine applications. In offshore applications, the drilling risers are generally made of pipeline steel that is used for extraction activity from the wells. The riser suffers a great loss due to corrosion in the marine splash zone. Nowadays, the dissimilar weld joints of super duplex stainless steels and pipeline steels are used for this critical region. In this study, gas tungsten arc welding is used to prepare two dissimilar welded joints of API X70 line pipe steel and super duplex stainless steel Grade 2507 using austenitic 309L and super duplex 2594 fillers. The specimens for corrosion tests are extracted from the base metals, weld fusion zone, and mixed zones (weld +HAZ+ base) for both dissimilar welded joints. The effect of austenite to ferrite ratio on their corrosion resistance is studied in the aqueous environment of a 3.5% NaCl solution. The chromium (Cr) and nickel (Ni) variation across the welds are studied using EPMA and EDS analysis. The combined effect of Cr and Ni elements is also studied on their corrosion resistance. Super duplex 2594 filler weld has superior corrosion resistance as compared to austenitic 309L filler weld. Moreover, the corrosion resistance (CR) among different weld sections varies as follows: CRweld zone > CRmixed zone 2507 side > CRmixed zone X70 side. The surfaces of various zones after the corrosion test are analyzed using a field emission scanning electron microscope. In weld zones, lower austenite to ferrite ratio resulted in poor corrosion resistance. The comparison of corrosion resistance of welds with the base metals brings out the need and suitability of employing this joint. The results of element variation at interphase and insight into corrosion resistance of different sections of weld help in deciding the need for corrective measures such as buttering and buffer interla |
Proceedings Inclusion? |
Definite: Other |