Residual stresses in laser direct metal deposited Waspaloy

Moat, Richard; Pinkerton, Andrew J.; Li, L.; Withers, Philip J.; Preuss, Michael

doi:10.1016/j.msea.2010.12.010

Cited by 163 publications

(94 citation statements)

References 28 publications

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“…These compressive stresses were present in the core of the structures while tensile stresses counter balanced them at the outer edges of the samples [11]. However, contrarily to Rangaswamy et al [11], Moat et al [10] additionally found large tensile residual stresses in the transverse direction along the building direction. These were present at the center top of the build-up.…”

Section: Residual Stressesmentioning

confidence: 90%

“…An additional result of the lowered cooling rate is that the surface of the deposit has large tensile residual stresses, contrary to the effect of a heat treated material where compressive residual stresses are expected at the surface. The distribution of residual stresses as described by Moat et al [10] where large residual tensile stresses are located at the surface of the deposit is reducing the mechanical properties of the as-deposited samples. This in may suggest that a solution heat treatment with a subsequent aging treatment is necessary in order to relax the samples and attain satisfactory mechanical properties.…”

Section: Discussionmentioning

confidence: 99%

“…These elements include: aluminum, boron, carbon, chromium, cobalt, hafnium, iron, magnesium, manganese, molybdenum, niobium, rhenium, tantalum, titanium, tungsten, and zirconium [15]. A broad range of superalloys has been evaluated for LMD including Alloy-625 [13,[16][17][18][19][20], Alloy-718 [6,[21][22][23][24][25][26][27][28][29][30][31], Alloy-738 [12,32], CMSX4 [33][34][35], Rene41 [36,37] and Waspaloy [10,38]. There are some parameters of particular importance to LMD, as listed in Table 1, to have a controlled deposition.…”

Section: Materials Characteristics and Process Parametersmentioning

confidence: 99%

“…Moving down from top to bottom the tensile transverse residual stresses in the longitudinal direction went from approximately 420 MPa to 0 MPa while the compressive residual stresses in the vertical build-up direction increased from approximately 0 MPa to 410 MPa. These measurements where done on deposited Waspaloy on an Alloy-718 substrate [10].…”

Section: Residual Stressesmentioning

confidence: 99%

“…Laser metal deposition with powder Deposition of material directly on a metal surface using laser is known by many different names such as: laser metal deposition (LMD), direct metal deposition or laser direct metal deposition [6][7][8][9][10], laser engineered net shaping [11], laser consolidation [12], laser rapid manufacturing [13] and more. LMD is a novel method of additive manufacturing which uses a multi-axis CNC machine or robot to guide the laser beam and powder nozzle over the deposition surface.…”

Section: Introductionmentioning

confidence: 99%

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Review of Laser Deposited Superalloys Using Powder as an Additive

Segerstark¹,

Andersson²,

Svensson³

2014

8th International Symposium on Superalloy 718 and Derivatives (2014)

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In this paper laser metal deposition (LMD) with blown powder was reviewed with respect to the material behavior of nickel and nickel-iron based superalloys. The key benefits of LMD are claimed to be increased design freedom of components as well as reduced environmental impact since it enables near net shape manufacturing. This review considers the LMD processing parameters such as laser power, powder feed rate, spot size, standoff distance, and traverse speed, together with aspects related to the powder e.g. morphology, porosity, inclusion and satellite content. Special emphasis was put on how these parameters affect the deposit and substrate in terms of cracking, porosity, inclusions, phase transformations, and other material related phenomena. A characteristic microstructure of LMD deposited superalloys has a columnar dendrite growth in the vertical build up direction. The grain growth can however be manipulated, making it more equiaxed by, for instance, altering process parameters and/or scanning path. Residual stresses in LMD samples are unevenly distributed and large residual tensile stresses can be found at the surface of the deposit while large compressive stresses are located close to the substrate in the core of the deposit. One of the most important parameter is considered to be the specific energy input which largely influences the m elt pool during deposition which in turn can be related to the microstructure, residual stress and, process related defects such as porosity, cracking, lack of fusion and, dilution.

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Section: Residual Stressesmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Materials Characteristics and Process Parametersmentioning

confidence: 99%

Section: Residual Stressesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Review of Laser Deposited Superalloys Using Powder as an Additive

Segerstark¹,

Andersson²,

Svensson³

2014

8th International Symposium on Superalloy 718 and Derivatives (2014)

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The Contour Method

Prime

DeWald

2013

Practical Residual Stress Measurement Methods

111

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The contour method, which is based upon solid mechanics, determines residual stress through an experiment that involves carefully cutting a specimen into two pieces and measuring the resulting deformation due to residual stress redistribution. The measured displacement data are used to compute residual stresses through an analysis that involves a finite element model of the specimen. As part of the analysis, the measured deformation is imposed as a set of displacement boundary conditions on the model. The finite element model accounts for the stiffness of the material and part geometry to provide a unique result. The output is a two-dimensional map of residual stress normal to the measurement plane. The contour method is particularly useful for complex, spatially varying residual stress fields that are difficult (or slow) to map using conventional point wise measurement techniques. For example, the complex spatial variations of residual stress typical of welds are well-characterized using the contour method.Contour method measurements are typically performed on metallic parts, which can be cut using a wire electric discharge machine (EDM). There are no specific size restrictions, but the measurement signal (displacement) scales with specimen size and performing measurements on parts smaller than 5 mm by 5 mm in cross-section requires extreme precision. There are no restrictions on the shape of the specimen due to the fact that complex geometry is accounted for using a finite element model of the part.The contour method is the youngest method covered in this book, having been first presented at a conference in 2000 [1] and then in a journal in 2001 [2]. Therefore, consensus Practical Residual Stress Measurement Methods, First Edition. Edited by Gary S. Schajer.

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Laser Powder Bed Fabrication of Nickel‐Base Superalloys: Influence of Parameters; Characterisation, Quantification and Mitigation of Cracking

2012

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The use of a selective laser melting (SLM) powder-bed method to manufacture Ni-based superalloys components provides an economic approach for low production run components that operate under a high-temperature and stress environment. A major concern with the SLM of precipitation hardenable Ni-based superalloys is their high susceptibility to cracking, which has been heavily documented in the field of welding. Weld cracking may occur either during processing (hot cracking, liquation cracking and ductility-dip cracking) or during the post weld heat-treatment stage (strain-age cracking). Due to the complex thermal history of SLM fabricated material there is the potential for all of these mechanisms to be active.In this investigation, cuboidal coupons of the Ni-based superalloy CM247LC were fabricated by the SLM of argon gas atomised powder. Parametric studies were performed to investigate the influence of the process parameters (laser scan speed, power and scan spacing) on the cracking density and morphology through conducting a stereological study of scanning electron microscope (SEM) micrographs. Further microstructural evidence is presented, illustrating the different crack morphologies observed as well as suggesting the responsible mechanisms. Finally a postfabrication Hot Isostatic Pressing (HIP) treatment was performed to investigate its utility in 'healing' the internal cracks, and providing a route to retro-fix the cracking problem in the heat treatment stage of production. The findings highlight the need for process models of the SLM method in order to understand the thermal history and the laser fabricated structures observed.

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Residual stresses in laser direct metal deposited Waspaloy

Cited by 163 publications

References 28 publications

Review of Laser Deposited Superalloys Using Powder as an Additive

Review of Laser Deposited Superalloys Using Powder as an Additive

The Contour Method

Laser Powder Bed Fabrication of Nickel‐Base Superalloys: Influence of Parameters; Characterisation, Quantification and Mitigation of Cracking

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