Role of long term ageing on the creep life of type 316H austenitic stainless steel bifurcation weldments

Ana I. Martinez-Ubeda, Oliver D. Payton, Tom B. Scott, Ian Griffiths, Charles M. Younes, Peter E J Flewitt

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

1 Citation (Scopus)

Abstract

Intergranular creep cracks have been observed in the heat affected zone of the 316H austenitic stainless steel superheater boiler tube bifurcation weldments after long term service at temperature of ∼550°C. The cracking mechanism is believed to be creep dominated. Moreover, chemical composition of defective material compared with similar uncracked components suggests that composition influences susceptibility to creep cracking. A systematic characterization of ratios number of creep cavities/grain boundary length and inter-granular precipitation length/grain boundary length has been undertaken in HAZ of three samples extracted from plants with different specific compositions. Here, the role of precipitation on creep deformation and fracture is explored. Precipitates of both ferrite and M23C6 carbide arising from long term service and associated creep cavitation have been identified using transmission electron microscopy. The creep damage and cracking, and therefore overall service life creep, is discussed by consideration of susceptibility of creep cavity nucleation and subsequently growth arising from specific differences in the chemical composition of the three boiler tube bifurcations.

Original languageEnglish
Title of host publicationMaterials and Fabrication
PublisherAmerican Society of Mechanical Engineers (ASME)
Volume6A-2016
ISBN (Electronic)9780791850428
DOIs
Publication statusPublished - 2016
EventASME 2016 Pressure Vessels and Piping Conference, PVP 2016 - Vancouver, Canada
Duration: 17 Jul 201621 Jul 2016

Conference

ConferenceASME 2016 Pressure Vessels and Piping Conference, PVP 2016
CountryCanada
CityVancouver
Period17/07/1621/07/16

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