Microstructure modeling of high-temperature microcrack initiation and evolution in a welded 9Cr martensitic steel. (October 2019)

• Record Type: Journal Article
• Authors: Li, M; O'Donoghue, PE; Leen, SB
• Is Part Of: Proceedings of the Institution of Mechanical Engineers. Volume 233:Number 10(2019)
• Page Start: 2160
• Page End: 2174
• Publication Date: 2019-10
• Subjects: Crystal plasticity -- weld -- inter-critical heat-affected zone -- ferrite -- crack nucleation and evolution; Materials -- Periodicals; Engineering design -- Periodicals; 620.11
• DOI: 10.1177/1464420719833086
• Languages: English
• ISSNs: 1464-4207

Abstract

Welded joints in tempered 9Cr–1Mo operating at elevated temperatures are well known to be prone to premature failure due to cracking in the heat-affected zone. This paper describes a crystal plasticity model to predict the microcrack initiation and evolution in the inter-critical heat-affected zone of 9Cr–1Mo welded steel at elevated temperature. A crystal plasticity finite element model indicates that the micro-cracks of 9Cr–1Mo steel mostly nucleate at prior austenite grain boundaries and boundary clustered regions. Inter-granular and trans-granular microcracking are shown to be the key predicted microdamage mechanisms from the current crystal plasticity model. A small amount of ferrite in the inter-critical heat-affected zone is shown to not only influence the microcrack initiation and evolution, but also significantly accentuate material degradation for a given applied load leading to premature failure at high temperature.