Residual Stress Characterization in a Dissimilar Metal Weld Nuclear Reactor Piping System Mock Up

Kerr, Matthew; Prime, Michael B.; Swenson, Hunter; Buechler, Miles A.; Steinzig, M.; Clausen, B.; Sisneros, Thomas A.

doi:10.1115/1.4024446

Cited by 13 publications

(8 citation statements)

References 29 publications

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“…The difference in microstructures between AM and wrought components can be significant, similar to the changes observed within welded microstructures. In some cases, welding can lead to introduction of additional phases, such as the appearance of ferrite in austenitic stainless steels [6], and welding processes often result in substantial residual stresses in and around the welded region [7] due to large thermal gradients and rapid cooling. These features are often present in AM materials as well [8,9].The…”

Section: Introductionmentioning

confidence: 99%

“…AM processing parameters have perhaps the strongest influence on component microstructure, and significant research is being performed to establish both empirical connections between the input parameters and the achieved microstructure and properties, and physics-based models to guide AM process optimization [5].The difference in microstructures between AM and wrought components can be significant, similar to the changes observed within welded microstructures. In some cases, welding can lead to introduction of additional phases, such as the appearance of ferrite in austenitic stainless steels [6], and welding processes often result in substantial residual stresses in and around the welded region [7] due to large thermal gradients and rapid cooling. These features are often present in AM materials as well [8,9].The…”

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confidence: 99%

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Deformation behavior of additively manufactured GP1 stainless steel

Clausen

Brown

Carpenter

et al. 2017

Materials Science and Engineering: A

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In-situ neutron diffraction measurements were performed during heat-treating and uniaxial loading of additively manufactured (AM) GP1 material. Although the measured chemical composition of the GP1 powder falls within the composition specifications of 17-4 PH steel, a fully martensitic alloy in the wrought condition, the crystal structure of the as-built GP1 material is fully austenitic. Chemical analysis of the as-built material shows high oxygen and nitrogen content, which then significantly decreased after heat-treating in a vacuum furnace at 650 °C for one hour. Significant austenite-to-martensite phase transformation is observed during compressive and tensile loading of the as-built and heat-treated material with accompanied strengthening as martensite volume fraction increases. During loading, the initial average phase stress state in the martensite is hydrostatic compression independent of the loading direction. Preferred orientation transformation in austenite and applied load accommodation by variant selection in martensite are observed via measurements of the texture development. Introduction.Additive manufacturing (AM) is a rapidly developing processing pathway that produces components by selectively melting and solidifying feedstock to build a desired geometry, rather than subtractive machining from cast or wrought stock material [1,2]. A major difference between the two routes is the microstructure of the material in the final component [3]. Casting and thermo-mechanical processing to produce wrought stock material has been optimized over centuries and a wide variety of thermal and deformation processing options are commonly used to obtain a desired component microstructure, which defines performance. In contrast, there are more limited opportunities to optimize microstructures of AM materials after manufacture, primarily because components are built to near-net shape to minimize the amount of material and post-build machining needed. As a result, most bulk thermo-mechanical treatments, (e.g., rolling, forging, etc.) cannot be readily applied. Options for modifying AM component microstructures after manufacture are generally limited to surface deformation treatments (e.g., shot or laser peening) and bulk or surface thermal/chemical treatments [4]. AM processing parameters have perhaps the strongest influence on component microstructure, and significant research is being performed to establish both empirical connections between the input parameters and the achieved microstructure and properties, and physics-based models to guide AM process optimization [5].The difference in microstructures between AM and wrought components can be significant, similar to the changes observed within welded microstructures. In some cases, welding can lead to introduction of additional phases, such as the appearance of ferrite in austenitic stainless steels [6], and welding processes often result in substantial residual stresses in and around the welded region [7] due to large thermal gradients and rapid cooling. These fe...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Deformation behavior of additively manufactured GP1 stainless steel

Clausen

Brown

Carpenter

et al. 2017

Materials Science and Engineering: A

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“…For typical piping systems, there are concerns about both axial and circumferential cracks, which requires knowledge of hoop and axial residual stresses. Residual stress data are essential for accurate crack initiation and growth assessment [5]. Furthermore, structural integrity assessment of operating power plants relies upon design codes and procedures [6,7], that make simplified assumptions regarding the residual stresses present in welds.…”

Section: Introductionmentioning

confidence: 99%

Measured Biaxial Residual Stress Maps in a Stainless Steel Weld

Olson

Hill

Patel

et al. 2015

Journal of Nuclear Engineering and Radiation Science

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This paper describes a sequence of residual stress measurements made to determine a two-dimensional map of biaxial residual stress in a stainless steel weld. A long stainless steel (316L) plate with an eight-pass groove weld (308L filler) was used. The biaxial stress measurements follow a recently developed approach, comprising a combination of contour method and slitting measurements, with a computation to determine the effects of out-of-plane stress on a thin slice. The measured longitudinal stress is highly tensile in the weld- and heat-affected zone, with a maximum around 450 MPa, and compressive stress toward the transverse edges around −250 MPa. The total transverse stress has a banded profile in the weld with highly tensile stress at the bottom of the plate (y = 0) of 400 MPa, rapidly changing to compressive stress (at y = 5 mm) of −200 MPa, then tensile stress at the weld root (y = 17 mm) and in the weld around 200 MPa, followed by compressive stress at the top of the weld at around −150 MPa. The results of the biaxial map compare well with the results of neutron diffraction measurements and output from a computational weld simulation.

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“…There is a difference of 1.75 mm along the build direction between the loci of the CM and the ND measurement locations, nevertheless, the two disparate stress measurement techniques produce very similar results, enabling a great deal of confidence in both. [50,51,52]. The added confidence in applying the two distinct measurement techniques to the same or similar samples enhances the experimental results when used for validation of process model simulations.…”

Section: Contour Methodmentioning

confidence: 98%

Complementary Measurements of Residual Stresses Before and After Base Plate Removal in an Intricate Additively-Manufactured Stainless-Steel Valve Housing

Clausen

D’Elia

Prime

et al. 2020

Additive Manufacturing

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Residual stress measurements using neutron diffraction and the contour method were performed on a valve housing made from 316L stainless steel powder with intricate three-dimensional internal features using laser powder-bed fusion additive manufacturing. The measurements captured the evolution of the residual stress fields from a state where the valve housing was attached to the base plate to a state where the housing was cut free from the base plate. Making use of this cut, thus making it a nondestructive measurement in this application, the contour method mapped the residual stress component normal to the cut plane (this stress field is completely relieved by cutting) over the whole cut plane, as well as the change in all stresses in the entire housing due to the cut. The non-destructive nature of the neutron diffraction measurements enabled measurements of residual stress at various points in the build prior to cutting and again after cutting. Good agreement was observed between the two measurement techniques, which showed large, tensile build-direction residual stresses in the outer regions of the housing. The contour results showed large changes in multiple stress components upon removal of the build from the base plate in two distinct regions: near the plane where the build was cut free from the base plate and near the internal features that act as stress concentrators. These observations should be useful in understanding the driving mechanisms for builds cracking near the base plate and to identify regions of concern for structural integrity. Neutron diffraction measurements were also used to show the shear stresses near the base plate were significantly lower than normal stresses, an important assumption for the contour method because of the asymmetric cut.

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Residual Stress Characterization in a Dissimilar Metal Weld Nuclear Reactor Piping System Mock Up

Cited by 13 publications

References 29 publications

Deformation behavior of additively manufactured GP1 stainless steel

Deformation behavior of additively manufactured GP1 stainless steel

Measured Biaxial Residual Stress Maps in a Stainless Steel Weld

Complementary Measurements of Residual Stresses Before and After Base Plate Removal in an Intricate Additively-Manufactured Stainless-Steel Valve Housing

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