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Title: Factors contributing to heat affected zone damage in Grade 91 steel feature type cross-weld tests
Authors: Siefert, John A.
Parker, Jonathan D.
Thomson, Rachel C.
Keywords: Grade 91
Heat affected zone
Damage
Cross-weld
Creep
Issue Date: 2017
Publisher: Stahleisen
Citation: SIEFERT, J.A., PARKER, J.D. and THOMSON, R.C., 2017. Factors contributing to heat affected zone damage in Grade 91 steel feature type cross-weld tests. Presented at the 4th International ECCC Creep & Fracture Conference, Dusseldorf, Germany, 10th-14th September 2017.
Abstract: Grade 91 steel has been widely utilized in power plants over the last 20 years. Its specification worldwide has dramatically increased since the acceptance of ASME Code Case 1943 for this material in 1983. Recent evaluation of a combination of ex-service Grade 91 steel components and virgin material has provided a unique opportunity to revisit commonly stated factors which contribute to damage in cross-weld creep tests. The approach adopted here is grounded in the fundamental objective of linking metallurgical risk factors in Grade 91 steel to the cross-weld creep performance. Establishing metallurgical risk factors in 9%Cr steels is regarded as a key consideration in the integration of a well-engineered life management strategy for these complex materials. In this study, two heats of ex-service Grade 91 steel which exhibit a similar response to the deformation resistance (i.e. strength) but dramatic differences in the susceptibility to damage (i.e. creep ductility) were evaluated in the welded condition using large, feature type cross-weld creep samples. Heat affected zone damage was investigated from both a macro-damage and micro-damage perspective. The macro-damage evaluation provided a comprehensive understanding of the global damage distribution through the heat affected zone (HAZ). The damage was linked to extensive hardness mapping and calculated peak temperatures through the HAZ. The microdamage characterization included a number of local observations for cavities in each sample using scanning electron microscope techniques. General observations were made regarding the shape and size of creep cavities and association of damage with microstructural features. These observations were linked to the as-fabricated microstructure and as characterized by electron backscatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDS) mapping.
Description: This is a conference paper.
Version: Accepted for publication
URI: https://dspace.lboro.ac.uk/2134/26413
Publisher Link: https://eccc2017.com/home.html
https://www.stahleisen.de/
ISBN: 9783514008328
Appears in Collections:Conference Papers and Presentations (Materials)

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