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Applying Lessons from Welding to Large Scale Metal Additive Manufacturing

Direct energy deposition processes that utilize wire feedstock have been deployed to deposit and fabricate near net shape functional metal parts at high deposition rates. Is this just multi-pass welding or is there more to it? Should the material requirements for additive be the same as those defined for welding? Is weld quality the same as part quality? A large metal additive part fabricated using a robotic wire arc additive system will be used to demonstrate the similarities and identify critical differences between essential variables for welding and additive manufacturing. The opportunities for both welding and additive manufacturing to learn and leverage one another to develop unique and novel materials, process controls and further fundamental understanding of metal deposition processes will be outlined.

Product Number: MPWT19-15370
Author: Michael Kottman, Mark Douglass, Badri K. Narayanan
Publication Date: 2019
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Product Number: MPWT19-14326
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Picture for A Review on Residual Stresses in the Fabrication Domain: Evolution Mechanisms, Quantification Techniques and Treatment Methods
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A Review on Residual Stresses in the Fabrication Domain: Evolution Mechanisms, Quantification Techniques and Treatment Methods

Product Number: MPWT19-14359
Author: Rashed Alhajri, Fahad Alhindas, Yasser Alsubhi, Hatim Alhamdan
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Residual stresses are self-equilibrating stresses that exist in materials and structures at the absence of instantaneous application of external loadings. In industrial manufacturing and fabrication processes, such stresses can be prominent and may lead to premature failures if uncontrolled. Such failures can be manifested in many forms including stress corrosion cracking, fatigue cracking or brittle facture. This paper is devoted to providing a comprehensive review on residual stress in the manufacturing and fabrication domain with a greater emphasis on welding based residual stresses. Three residual stress evolution mechanisms will be evaluated covering deformation driven stresses during manufacturing, thermally driven during welding and surface modifications such as grinding, carburizing and plating. In welding processes, the residual stresses in the cooling cycle are characterized using Gleeble testing illustrating the stress profiles as a function of temperature. The effect of residual stresses in welded structures will be discussed covering fatigue performance, brittle fracture and effect on Stress Corrosion Cracking resistance. To ensure residual stresses are effectively measured and quantified, a total of nine (9) destructive, semi-destructive and non-destructive residual stress measurement techniques are evaluated. A comparison and evaluation of four (4) common residual stress mitigation techniques are also discussed covering Ultrasonic Impact Treatment, High Frequency Mechanical Impact, shot peening and Post-weld Heat Treatment. The review discussion extends to four (4) factors towards impacting the residual stress magnitude and distribution covering material properties, welding process and clamping and preheating during welding.