Residual Stress Distributions in Cold-Sprayed Copper 3D-Printed Parts

AbstractCold-spray additive manufacturing (CSAM) builds strong, dense metal parts from powder feedstock without melting and offers potential advantages over alternatives such as casting, liquid phase sintering, laser or e-beam melting or welding. Considerable effort is required to relieve residual stresses that arise from melt/freeze cycling in these methods. While CSAM does not involve melting, it imposes high strain rates on the feedstock and stress anisotropies due to complex build paths. This project explores residual stress in two CSAM objects. The CSAM components were produced from 99% pure copper powder (D50 = 17 µm): (1) a cylinder (∅ = 15 mm, height = 100 mm, weight = 145 g) and (2) a funnel (upper outer ∅ = 60 mm, lower outer ∅ = 40 mm, wall thickness = 8 mm, weight = 547 g). The non-heat-treated components were strain-scanned using a residual stress neutron diffractometer. Maximum residual stresses in any direction were: tensile: 103 ± 16 MPa (cylinder) and 100 ± 23 MPa (funnel); compression: 58 ± 16 MPa (cylinder) and 123 ± 23 MPa (funnel). Compared to the literature, the tensile residual stresses measured in the CSAM components were lower than those measured in cast materials, laser or welding AM methods, and numerical modelling of cold-spray coatings, while within the wide range reported for measurements in cold-spray coatings. These comparatively low residual stresses suggest CSAM is a promising manufacturing method where high residual stresses are undesirable.

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Residual Stress Enhancement in 3D Printed Inconel 718 Superalloy Treated by Ultrasonic Nano-Crystal Surface Modification

Volume 2: Additive Manufacturing; Materials ◽

10.1115/msec2017-2918 ◽

2017 ◽

Author(s):

Kuldeep Singh Sidhu ◽

Jing Shi ◽

Vijay K. Vasudevan ◽

Seetha Ramaiah Mannava

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

Surface Modification ◽

Residual Stresses ◽

Inconel 718 ◽

Crystal Surface ◽

High Temperature Strength ◽

Heat Treated ◽

Wide Range ◽

Inconel 718 Superalloy

Inconel 718 (IN718) is a nickel based Ni-Cr-Fe super alloy. It has a unique set of properties such as good workability, corrosion resistance, high temperature strength, favorable weldability and excellent manufacturability. Due to its wide range of applications, IN718 is an alloy of great interest for many industries. Meanwhile, additive manufacturing assisted with laser has caught much interest from researchers and practitioners in the past three decades. In this study, IN718 alloy coupons are manufactured by selective laser melting (SLM) technique. The SLMed IN718 alloys are treated by ultrasonic nanocrystal surface modification (UNSM), and the residual stress distributions underneath the surfaces are measured. It is found that residual stress mostly tensile is induced while building the part by the SLM technique. The tensile stresses can be reduced to almost zero value by post heat treatment. Moreover, the heat treatment helps to homogenize the microstructure, and results in the increase in hardness. More importantly, it is observed that UNSM effectively induces compressive residual stresses in the as-built and heat-treated parts. The residual stresses of compressive nature in as built parts has depth of around 530 μm where as in heat treated parts has a depth of around 530μm.

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Additive Manufactured 316L Stainless-Steel Samples: Microstructure, Residual Stress and Corrosion Characteristics after Post-Processing

Metals ◽

10.3390/met11020182 ◽

2021 ◽

Vol 11 (2) ◽

pp. 182

Author(s):

Suvi Santa-aho ◽

Mika Kiviluoma ◽

Tuomas Jokiaho ◽

Tejas Gundgire ◽

Mari Honkanen ◽

...

Keyword(s):

Residual Stress ◽

Residual Stresses ◽

Sample Surface ◽

Post Processing ◽

Magnesium Chloride Solution ◽

Manufacturing Method ◽

Four Point Bending ◽

Traditional Manufacturing ◽

Processing Steps ◽

Compressive Residual Stresses

Additive manufacturing (AM) is a relatively new manufacturing method that can produce complex geometries and optimized shapes with less process steps. In addition to distinct microstructural features, residual stresses and their formation are also inherent to AM components. AM components require several post-processing steps before they are ready for use. To change the traditional manufacturing method to AM, comprehensive characterization is needed to verify the suitability of AM components. On very demanding corrosion atmospheres, the question is does AM lower or eliminate the risk of stress corrosion cracking (SCC) compared to welded 316L components? This work concentrates on post-processing and its influence on the microstructure and surface and subsurface residual stresses. The shot peening (SP) post-processing levelled out the residual stress differences, producing compressive residual stresses of more than −400 MPa in the AM samples and the effect exceeded an over 100 µm layer below the surface. Post-processing caused grain refinement and low-angle boundary formation on the sample surface layer and silicon carbide (SiC) residue adhesion, which should be taken into account when using the components. Immersion tests with four-point-bending in the heated 80 °C magnesium chloride solution for SCC showed no difference between AM and reference samples even after a 674 h immersion.

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Changes in Residual Stress in Worked Surface Layer of Type 304 Austenitic Stainless Steel Due to Tensile Deformation

Journal of Pressure Vessel Technology ◽

10.1115/1.1339006 ◽

2000 ◽

Vol 123 (1) ◽

pp. 130-134

Author(s):

Makoto Hayashi ◽

Kunio Enomoto

Keyword(s):

Solid Solution ◽

Residual Stress ◽

Stainless Steel ◽

Surface Layer ◽

Residual Stresses ◽

Tensile Deformation ◽

End Mill ◽

Heat Treated ◽

304 Austenitic Stainless Steel ◽

Type 304

Changes in the residual stress in a worked surface layer of type 304 austenitic stainless steel due to tensile deformation were measured by the X-ray diffraction residual stress measuring method. The compressive residual stresses introduced by end-mill, end-mill side cutter, and grinder were easily changed into tensile stresses when the plate specimens were subjected to tensile stress greater than the yield stress of the solid solution heat-treated material. The residual stresses after the tensile deformation depend on the initial residual stresses and the degree of preliminary working. The behavior of the residual stress changes can be interpreted if the surface-worked material is regarded as a composite made of solid solution heat-treated material and work-hardened material.

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Theoretical prediction of residual stresses induced by cold spray with experimental validation

Multidiscipline Modeling in Materials and Structures ◽

10.1108/mmms-08-2018-0150 ◽

2019 ◽

Vol 15 (3) ◽

pp. 599-616 ◽

Cited By ~ 4

Author(s):

Dibakor Boruah ◽

Xiang Zhang ◽

Matthew Doré

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Residual Stresses ◽

Cold Spray ◽

Residual Stress Distribution ◽

Thermal Mismatch ◽

Individual Layer ◽

Content Type ◽

Layer Height ◽

Proposed Model

PurposeThe purpose of this paper is to develop a simple analytical model for predicting the through-thickness distribution of residual stresses in a cold spray (CS) deposit-substrate assembly.Design/methodology/approachLayer-by-layer build-up of residual stresses induced by both the peening dominant and thermal mismatch dominant CS processes, taking into account the force and moment equilibrium requirements. The proposed model has been validated with the neutron diffraction measurements, taken from the published literature for different combinations of deposit-substrate assemblies comprising Cu, Mg, Ti, Al and Al alloys.FindingsThrough a parametric study, the influence of geometrical variables (number of layers, substrate height and individual layer height) on the through-thickness residual stress distribution and magnitude are elucidated. Both the number of deposited layers and substrate height affect residual stress magnitude, whereas the individual layer height has little effect. A good agreement has been achieved between the experimentally measured stress distributions and predictions by the proposed model.Originality/valueThe proposed model provides a more thorough explanation of residual stress development mechanisms by the CS process along with mathematical representation. Comparing to existing analytical and finite element methods, it provides a quicker estimation of the residual stress distribution and magnitude. This paper provides comparisons and contrast of the two different residual stress mechanisms: the peening dominant and the thermal mismatch dominant. The proposed model allows parametric studies of geometric variables, and can potentially contribute to CS process optimisation aiming at residual stress control.

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A Limiting Defect Study of an Elbow

ASME 2011 Pressure Vessels and Piping Conference: Volume 3 ◽

10.1115/pvp2011-57027 ◽

2011 ◽

Cited By ~ 1

Author(s):

Jinhua Shi ◽

David Blythe

Keyword(s):

Residual Stress ◽

Residual Stresses ◽

Hoop Stress ◽

Defect Size ◽

Welding Residual Stress ◽

Central Section ◽

Butt Welding ◽

Wide Range ◽

Stress Components ◽

Hoop Stresses

In order to ensure the integrity of a seamless butt-welding elbow, both the central section and ends of the elbow need to be assessed, as the maximum stress is normally located at the central section of the elbow but there are no welding residual stresses. Furthermore, at the ends (welds) of the elbow, very high welding residual stresses exist if the welds have not been post weld heat treated but the primary stresses induced by the internal pressure and system moments are lower. For a 90 degree elbow welded to seamless straight pipe, both maximum axial and hoop stress components in the elbow can be calculated using ASME III NB-3685. At the ends of the elbow, axial and hoop stress components can be obtained using the stress equations presented in the paper of PVP2010-25055. In this paper, a series of limiting defect assessments have been carried out on an elbow assuming a postulated axial external defect as follows: • A number of assessments have been conducted directly using the axial and hoop stresses calculated based on ASME III NB-3685 for different system moments. • A series of assessments have been carried out using the axial and hoop stresses calculated using the stress equations presented in the paper of PVP2010-25055, a wide range of welding residual stresses and different system moments. A comparison of the assessment results in the elbow and at the ends of the elbow shows that when system moments are relatively low and the welding residual stress is high, the limiting defect size is located at the ends of the elbow; when the system moments are high and the welding residual stress is low the limiting defect size is located at the central section of the elbow. Therefore, it can be concluded that when assessing an elbow, the assessments should be carried out at both the central section and the ends of the elbow, in order to ensure the integrity of the elbow.

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Residual Stresses Induced by Surface Working and Their Improvement by Emery Paper Polishing

Quantum Beam Science ◽

10.3390/qubs4020021 ◽

2020 ◽

Vol 4 (2) ◽

pp. 21

Author(s):

Makoto Hayashi

Keyword(s):

Residual Stress ◽

Stainless Steel ◽

Fatigue Strength ◽

Residual Stresses ◽

Diffraction Method ◽

304 Stainless Steel ◽

Heat Treated ◽

Emery Paper ◽

Type 304 ◽

Type 304 Stainless Steel

In many of machine parts and structural components, materials surface would be worked. In this study, residual stresses on the surfaces were measured by X-ray diffraction method, and effects of surface working on the residual stresses were examined. In case of lathe machining of type 304 stainless steel bar, the residual stresses in circumferential directions are tensile, and those in axial directions are almost compressive. Highly tensile residual stresses in the circumferential directions were improved by emery paper polishing. 10 to 20 times of polishing changes high tensile residual stresses to compressive residual stresses. In the case of shot peening on a type 304 stainless steel plate, the compressive residual stress inside is several hundred MPa lower than that on the surface. By applying the emery paper polishing to the shot peened surface 10 or 20 times, the residual stress on the surface is improved to −700 MPa. While fatigue strength at 288 °C in the air of the shot peened material is 30 MPa higher than solution heat treated and electro-polished material, the fatigue strength of the shot peened and followed by emery paper polished material is 60 MPa higher. Thus, the emery paper polishing is simple and a very effective process for improvement of the residual stresses.

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Residual Stress Relief in the Aluminium Alloy 7075

Materials Science Forum ◽

10.4028/www.scientific.net/msf.905.31 ◽

2017 ◽

Vol 905 ◽

pp. 31-39 ◽

Cited By ~ 1

Author(s):

Jeremy S. Robinson ◽

Christopher E. Truman ◽

Thilo Pirling ◽

Tobias Panzner

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Neutron Diffraction ◽

Residual Stresses ◽

Aluminium Alloy ◽

Stress Relief ◽

Residual Stress Distribution ◽

Cold Compression ◽

Heat Treated ◽

Minimum Residual

The residual stresses in heat treated 7075 aluminium alloy blocks have been characterised using two neutron diffraction strain scanning instruments. The influence of uniaxial cold compression (1-10%) on relieving the residual stress has been determined. Increasing the magnitude of cold compression from 1 to 10% has been shown to have a beneficial effect on the residual stress distribution by reducing the range between the maximum and minimum residual stresses. The effect of over aging 7075 on residual stress has also been characterised using neutron diffraction and this was found to reduce the residual stress by 25-40%. A relationship between {311} peaks widths and amount of cold compression was also observed.

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Analysis on the Residual Stresses in the Aluminum Alloy Friction Stir Welded Joints

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.291-294.958 ◽

2011 ◽

Vol 291-294 ◽

pp. 958-963

Author(s):

Li Jie Cao

Keyword(s):

Residual Stress ◽

Aluminum Alloy ◽

Residual Stresses ◽

Simulation Analysis ◽

Engineering Application ◽

Stress Fields ◽

Weld Strength ◽

Technological Parameters ◽

Friction Stir ◽

Wide Range

The residual stress fields can have strong influences on the integrity and performance of friction stir welded aluminum alloy structure, comprehensive insight into the residual stress distribution is the key to the Friction stir welding (FSW) engineering application for a wide range of materials and thicknesses improving the weld strength and fatigue life. In this paper, the current state of the residual stresses in the FSW aluminum alloy joints is reviewed, The focus is on recent advances of experimental research, the results of numerical simulation analysis, and the effects of the technological parameters(welding speed, rotational speed, shoulder geometry et al.) on residual stress fields was evaluated. In the end, The controlling technique of residual stresses from published literatures is summarized.

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Experimental and Computational Residual Stress Evaluation of a Weld Clad Plate and Machined Test Specimens

Journal of Engineering Materials and Technology ◽

10.1115/1.3226053 ◽

1988 ◽

Vol 110 (4) ◽

pp. 297-304 ◽

Cited By ~ 9

Author(s):

E. F. Rybicki ◽

J. R. Shadley ◽

A. S. Sandhu ◽

R. B. Stonesifer

Keyword(s):

Residual Stress ◽

Residual Stresses ◽

Computational Model ◽

Stress Analysis ◽

Elevated Temperatures ◽

Stress Distributions ◽

Heat Treated ◽

Residual Stress Analysis ◽

The Difference ◽

Set Up

Residual stresses in a heat treated weld clad plate and test specimens obtained from the plate are determined using a combination of experimental residual stress analysis and a finite element computational model. The plate is 102 mm thick and made of A 533-B Class 2 steel with 308 stainless steel cladding. The plate is heated to 538 C and allowed to cool uniformly. Upon cooling, residual stresses are set up in the clad plate because of the difference between the coefficients of thermal expansion of the plate and the cladding. Residual stress in the clad plate is determined using both a previously verified experimental residual stress analysis technique and a computational model. Removing test specimens from the clad plate can relax the stresses in the cladding. Thus, residual stress distributions were also determined for two types of clad test specimens that were removed from the plate. These test specimens were designed to examine the effect of cladding thickness on residual stresses. Good agreement was found between the experimentally obtained residual stress values and the residual stresses calculated from the computational model. Because of the interest in tests conducted at elevated temperatures and the inherent difficulty in doing experimental residual stress analysis at elevated temperatures, the computational model was applied to examine the effect of elevated temperature on the residual stresses in the test specimens. Peak stresses in the heat treated clad plate were found to approach the yield stress of the cladding material. It was also found that removing a 32 mm clad specimen with cladding on one side reduced the residual stresses in the cladding. However, the residual stresses in the cladding were found to increase when one-half of the cladding thickness was machined away to form the second test specimen geometry. Residual stresses parallel and perpendicular to the weld direction were very similar in magnitude for all cases considered. The effect that heating the test specimens to 204 C has on residual stress distributions was to reduce the residual stress in the cladding and the plate.

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