Neutron Diffraction Residual Stress Study of a AA2219-T87 Self-Reacting Friction Stir Weld

• Published in: Journal of materials engineering and performance Vol. 33; no. 8; pp. 4149 - 4159
• Main Authors: Wing, B. J., Polsky, D., Bunn, J. R., Payzant, E. A., Rawn, C. J.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.04.2024
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Materials Science; Original Research Article; Quality Control; Reliability; Safety and Risk; Tribology; metallography; residual stress; nondestructive testing; welding; aerospace; aluminum
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-024-09278-w

2219-T87 is a precipitation hardenable aluminum-copper alloy which sees wide use in structural aerospace components. Thick panels of this alloy are joined via self-reacting friction welding (SRFSW); however, this thermomechanical process can result in significant loss of the alloy’s strengthening precipitates and large residual stresses which are detrimental to mechanical behavior and performance. High-resolution maps of the residual strain and stress states along the normal, transverse, and longitudinal directions of 2219-T87 SRFSW were obtained using neutron diffraction measurements. Residual stress had the highest tensile value in the heat-affected zone (HAZ) and the largest compressive stress in the base metal region of the normal and transverse directions. Line profile residual stress distributions displayed an “M”-shaped distribution in each direction with the longitudinal direction being the most pronounced while 2D residual stresses displayed an hourglass-shaped pattern. Average maximal longitudinal residual stress values ranged from 60.6 to 85.6% of yield. Microhardness testing across the transverse weld section produced a “V”-shaped curve with slight hardness recovery in the stir zone. Maximal and minimal microhardness values were observed in the base metal (154 HV) and thermomechanically affected zone (82 HV), respectively. Microstructural evolution was recorded using optical microscopy and showed decreasing grain size from the HAZ to the stir zone.