A comprehensive study on solidification (hot) cracking in austenitic stainless steel welds from a microstructural approach. (15th December 2021)

• Record Type: Journal Article
• Authors: Ramon, Jasper; Basu, Ritwik; Voort, George Vander; Bolar, Gururaj
• Is Part Of: International journal of pressure vessels and piping. Volume 194:Part B(2021)
• Publication Date: 2021-12-15
• Subjects: Hot cracking -- Crack sensitivity -- Strain localization -- Electron backscattered diffraction (EBSD) -- Kernel average misorientation (KAM) -- Stored energy; Pressure vessels -- Periodicals; Pipe -- Periodicals; Récipients sous pression -- Périodiques; Tuyaux -- Périodiques; Pipe; Pressure vessels; Periodicals; 681.76041
• DOI: 10.1016/j.ijpvp.2021.104560
• Languages: English
• ISSNs: 0308-0161

Abstract

Abstract: The present work evaluates solidification cracks in stainless steel welds that have been produced on a laboratory scale by carrying out a detailed EBSD (electron backscattered diffraction) investigation. The welding speed presented a near-linear relationship with the susceptibility to cracking. A wide range of microstructures were generated by varying the welding speed. The cracks were predominantly transgranular type and mainly propagated through grains with lower Taylor factors. These cracks were accompanied by a strong presence of a localized strain field (high local misorientation), which was observed by a higher presence of low angle grain boundaries (LAGBs). A correlation was found between the local in-grain misorientation and the crack sensitivity. With increased thermal tensile strains, certain LAGBs transformed into HAGBs to accommodate the strain and that resulted in the formation of strain-free grains. The elastic stored energy estimated from EBSD also showed an increase with the local misorientation. Graphical abstract: Samples showing two extreme conditions of strain concentration (local misorientation)— shown as green points in the kernel average misorientation (KAM) map. (a) lesser strain and (b) higher strain concentration. Sample corresponding to higher strain localization showed higher susceptibility to crack formation. The cracks were orientation sensitive. Cracks were mostly transgranular and visible in low Taylor factor (soft oriented) grains. Image 1 Highlights: A novel approach through EBSD techniques to understand the microstructural mechanisms of hot crack formation in SS welds. Crack sensitivity was seen to be a clear function of strain localization. Strain localization was accompanied by increased presence of low angle GB fraction and higher in-grain misorientation. The cracks were mostly transgranular in nature and sensitive to grain orientation.