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Holmberg, J., Wretland, A., Berglund, J. & Beno, T. (2020). A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth. Materials Today Communications, 24, Article ID 100958.
Open this publication in new window or tab >>A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth
2020 (English)In: Materials Today Communications, ISSN 2352-4928, Vol. 24, article id 100958Article in journal (Refereed) Published
Abstract [en]

Production of superalloy gas turbine parts involves time consuming milling operations typically performed in a sequence from rough to finish milling. Rough milling using ceramic inserts allows high removal rates but causes severe sub-surface impact. A relatively large allowance is therefore left for subsequent cemented carbide milling. With increased knowledge of the affected depth it will be possible to reduce the machining allowance and increase efficiency of the manufacturing process. Milling Inconel 718 using typical production parameters has been investigated using new and worn ceramic and cemented carbide inserts. Residual stresses in a milled slot were measured by x-ray diffraction. Stresses were measured laterally across the slot and below the surface, to study the depth affected by milling. The most important result from this work is the development of a framework concerning how to evaluate the affected depth for a milling operation. The evaluation of a single milled slot shows great potential for determining the optimum allowance for machining. Our results show that the residual stresses are greatly affected by the ceramic and cemented carbide milling; both regarding depth as well as distribution across the milled slot. It has been shown that it is important to consider that the stresses across a milled slot are the highest in the center of the slot and gradually decrease toward the edges. Different inserts, ceramic and cemented carbide, and tool wear, alter how the stresses are distributed across the slot and the affected depth.

Place, publisher, year, edition, pages
Elsevier Ltd, 2020
Keywords
Allowance determination, Alloy 718, High speed milling, Material removal rate, Residual stresses, Surface integrity, Carbide cutting tools, Carbide tools, Carbides, Milling (machining), Cutting tools
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-43938 (URN)10.1016/j.mtcomm.2020.100958 (DOI)2-s2.0-85079036532 (Scopus ID)
Note

Funding details: VINNOVA; Funding text 1: The results presented in this paper are part of the research project SWE DEMO MOTOR [grant number 2015-06047 ] financed by VINNOVA , the Swedish government agency for Enterprise and Innovation . Special thanks are due to GKN Aerospace Sweden AB for supplying test materials, information and expertise and to Tooltec Trestad AB for help in manufacturing the test specimens. The authors would also like to acknowledge the Knowledge Foundation (KK Stiftelsen) and the SiCoMaP research school.

Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-02-24
Holmberg, J., Berglund, J., Wretland, A. & Beno, T. (2019). Evaluation of surface integrity after high energy machining with EDM, laser beam machining and abrasive water jet machining of alloy 718. The International Journal of Advanced Manufacturing Technology, 100(5-8), 1575-1591
Open this publication in new window or tab >>Evaluation of surface integrity after high energy machining with EDM, laser beam machining and abrasive water jet machining of alloy 718
2019 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 100, no 5-8, p. 1575-1591Article in journal (Refereed) Published
Abstract [en]

Development of future aero engine components based on new design strategies utilising topological optimisation and additive manufacturing has in the past years become a reality. This allows for designs that involve geometries of “free form” surfaces and material combinations that could be difficult to machine using conventional milling. Hence, alternative manufacturing routes using non-conventional high energy methods are interesting to explore. In this investigation, the three high energy machining methods abrasive water jet machining (AWJM), electrical discharge machining (EDM) and laser beam machining (LBM) have been compared in terms of surface integrity to the reference, a ball nosed end milled surface. The results showed great influence on the surface integrity from the different machining methods. It was concluded that AWJM resulted in the highest quality regarding surface integrity properties with compressive residual stresses in the surface region and a low surface roughness with texture from the abrasive erosion. Further, it was shown that EDM resulted in shallow tensile residual stresses in the surface and an isotropic surface texture with higher surface roughness. However, even though both methods could be considered as possible alternatives to conventional milling they require post processing. The reason is that the surfaces need to be cleaned from either abrasive medium from AWJM or recast layer from EDM. It was further concluded that LBM should not be considered as an alternative in this case due to the deep detrimental impact from the machining process. © 2018, The Author(s).

Place, publisher, year, edition, pages
Springer London, 2019
Keywords
Abrasives; Aircraft engines; Electric discharge machining; Electric discharges; Jets; Laser beams; Manufacture; Milling (machining); Residual stresses; Surface roughness; Topography, Abrasive water jet machining; Aero-engine components; Compressive residual stress; EBSD; Electrical discharge machining; Nonconventional machining; Surface integrity; Tensile residual stress, Laser beam machining
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:ri:diva-35528 (URN)10.1007/s00170-018-2697-z (DOI)2-s2.0-85054583255 (Scopus ID)
Available from: 2018-10-30 Created: 2018-10-30 Last updated: 2020-01-30Bibliographically approved
Holmberg, J., Hammerberg, P., Lundin, P. & Olavison, J. (2019). Hardness depth assessment of induction hardened steel by a comparative approach using Barkhausen Noise and Ultrasonic signals. In: Proceedings of ICBM13: . Paper presented at ICBM13 - the 13th International Conference on Barkhausen Noise and Micromagnetic Testing, will be held in Prague, Czech Republic, from 23rd to 26th September 2019.
Open this publication in new window or tab >>Hardness depth assessment of induction hardened steel by a comparative approach using Barkhausen Noise and Ultrasonic signals
2019 (English)In: Proceedings of ICBM13, 2019Conference paper, Published paper (Other academic)
Abstract [en]

A major challenge in automotive industry when producing heat treated engine parts is achievement of necessary material properties for a given component to withstand loads during its use. Critical properties involve correct microstructure and hardening depth which is essential to verify from manufacturing.

Today this is solely done by destructive testing where manufactured parts are sectioned to smaller pieces and the properties is verified relative the operational window of the process. For the case of camshafts this is necessary every time the production is reset from one type to another or other planned or un-planned interruptions. The verification process is very costly, since production stands still.

The need for non-destructive alternatives is therefore obvious and prior investigations has shown great potential in both the Barkhausen noise (BN) and Ultrasonic testing (UT) methods. Recent research has also advanced the analysing methodology of the response signal for sub-surface microstructural characterization and case depth measurements. BN is well known of its sensitivity to microstructure and UT is also known to be effective for material characterization. One major difference between the two technologies is the sensitivity range (analysing depth) under the surface of the material to be characterized. Traditional BN is only effective within few tenths of millimetres from the surface while UT is sensitive to both surface and sub-surface characteristics of the material depending on the configuration.

The major motive in this investigation has been to compare the two methods and to investigate if a combination of these methods could be used for assessment of the hardening depth of induction hardened steels for the depth interval 2-7 mm. This is a typical depth range when manufacturing induction hardened cam shafts within the heavy automotive industry.

In the present investigation cylindrical steel specimens of grade C45 was induction hardened to generate different hardness depths. The heat treatment was performed in an induction hardening equipment by alternating the scanning speed and power. The produced specimens had hardness depth in the range 2-7 mm and was evaluated with by BN and UT measurements, independently, followed by destructive verification of the material properties.

The results show a potential for both BN and UT to measure the hardening depth down to 4 mm. It was further shown that several BN parameters correlate with the hardening depth indicating that a combination of different parameters may be used for assessment using a triangulation approach.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-40563 (URN)
Conference
ICBM13 - the 13th International Conference on Barkhausen Noise and Micromagnetic Testing, will be held in Prague, Czech Republic, from 23rd to 26th September 2019
Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2020-01-30Bibliographically approved
Suárez, A., Veiga, F., Polvorosa, R., Artaza, T., Holmberg, J., de Lacalle, L. N. & Wretland, A. (2019). Surface integrity and fatigue of non-conventional machined Alloy 718. Journal of Manufacturing Processes, 48, 44-50
Open this publication in new window or tab >>Surface integrity and fatigue of non-conventional machined Alloy 718
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2019 (English)In: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 48, p. 44-50Article in journal (Refereed) Published
Abstract [en]

Alloy 718 is a high-strength, corrosion-resistant nickel chromium-based superalloy frequently used for applications, such as aerospace, marine, nuclear reactor and chemical industries, due to its outstanding inherent properties such as high strength and corrosion resistance at high temperatures together with good creep behaviour. Although, the use of conventional manufacturing processes is prevalent for their use on Alloy 718, alternative manufacturing technologies are gaining importance. This work compares the effects of alternative manufacturing processes, such as Abrasive water jet (AWJ), Wire Electrical Discharge Machining (WEDM) and ultrasound vibration assisted milling (UVAM) with conventional milling during the manufacture of Alloy 718 parts. Surface integrity, hardness, residual stress and fatigue strength obtained from these machining processes have been examined for cutting alloy 718. Results show that both residual stresses and surface roughness are correlated with fatigue strength. UVAM results shown an improvement on the surface integrity of the final workpiece. AWJ and WEDM show poorer results, further work on post-process technologies or process condition selection must be carry out to establish them as an alternative in Alloy 718 cutting operations.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Alloy 718, AWJ, Fatigue, Surface integrity, UVAM, WEDM, Chemical industry, Chromium alloys, Corrosion resistance, Corrosion resistant alloys, Electric discharge machining, Electric discharges, Fatigue of materials, Manufacture, Marine applications, Milling (machining), Nickel alloys, Nuclear reactors, Residual stresses, Seawater corrosion, Surface roughness, Thermal fatigue, Alternative manufacturing process, High strength and corrosion resistances, Manufacturing technologies, Wire electrical discharge machining, High strength alloys
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-40772 (URN)10.1016/j.jmapro.2019.09.041 (DOI)2-s2.0-85074301762 (Scopus ID)
Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2019-11-25Bibliographically approved
Mahade, S., Ruelle, C., Curry, N., Holmberg, J., Björklund, S., Markocsan, N. & Nylén, P. (2019). Understanding the effect of material composition and microstructural design on the erosion behavior of plasma sprayed thermal barrier coatings. Applied Surface Science, 488, 170-184
Open this publication in new window or tab >>Understanding the effect of material composition and microstructural design on the erosion behavior of plasma sprayed thermal barrier coatings
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2019 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 488, p. 170-184Article in journal (Refereed) Published
Abstract [en]

In this work, three different TBC compositions comprising of yttria partially stabilized zirconia (8YSZ), yttria fully stabilized zirconia (48YSZ) and gadolinium zirconate (GZ) respectively, were processed by suspension plasma spray (SPS) to obtain columnar microstructured TBCs. Additionally, for comparison, lamellar microstructured, 7YSZ TBC was deposited by air plasma spray (APS) process. SEM analysis was carried out to investigate the microstructure and white light interferometry was used to evaluate the surface morphology of the as-sprayed TBCs. Porosity measurements were made using water intrusion and image analysis methods and it was observed that the SPS-YSZ and APS-YSZ TBCs showed higher porosity content than SPS-GZ and SPS-48YSZ. The as-sprayed TBC variations (APS-YSZ, SPS-YSZ, SPS-GZ, and SPS-48YSZ) were subjected to erosion test. Results indicate that the erosion resistance of APS-YSZ TBC was inferior to the SPS-YSZ, SPS-GZ and SPS-48YSZ TBCs respectively. Among the SPS processed TBCs, SPS-YSZ showed the highest erosion resistance whereas the SPS-48YSZ showed the lowest erosion resistance. SEM analysis of the eroded TBCs (cross section and surface morphology) was performed to gain further insights on their erosion behavior. Based on the erosion results and post erosion SEM analysis, erosion mechanisms for splat like microstructured APS TBC and columnar microstructured SPS TBCs were proposed. The findings from this work provide new insights on the erosion mechanisms of columnar microstructured TBCs and lamellar microstructured TBCs deposited by plasma spray.

Place, publisher, year, edition, pages
Elsevier B.V., 2019
Keywords
Atmospheric plasma spray, Erosion, Gadolinium zirconate (GZ), Suspension plasma spray, Yttria fully stabilized zirconia (48YSZ), Yttria partially stabilized zirconia (8YSZ), Microstructure, Morphology, Plasma jets, Porosity, Sprayed coatings, Surface morphology, Thermal barrier coatings, Yttria stabilized zirconia, Yttrium oxide, Zirconia, Gadolinium zirconate, Stabilized zirconia, Suspension plasma sprays, Yttria partially stabilized zirconia, Plasma spraying
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39380 (URN)10.1016/j.apsusc.2019.05.245 (DOI)2-s2.0-85066427612 (Scopus ID)
Note

 Funding details: Stiftelsen för Kunskaps- och Kompetensutveckling, Dnr 20140130; Funding text 1: The authors thank Professor Robert Vassen from FZ Jülich, Germany, Prof. Shrikant Joshi and Dr. Mohit Gupta from University West, Sweden for the insightful discussion on the results obtained in this work. The authors would like to thank SiCoMaP+ research school and the knowledge foundation ( KK Stiftelsen , Grant nr: Dnr 20140130 ), Sweden, for the financial support.

Available from: 2019-07-08 Created: 2019-07-08 Last updated: 2019-07-08Bibliographically approved
Holmberg, J., Rodri­guez Prieto, J. M., Berglund, J., Sveboda, A. & Jonsén, P. (2018). Experimental and PFEM-simulations of residual stresses from turning tests of a cylindrical Ti-6Al-4V shaft. Paper presented at Conference of 4th CIRP Conference on Surface Integrity, CIRP CSI 2018, 11-13 July, Tianjin, China. Conference Code: 140188. Procedia CIRP, 71, 144-149
Open this publication in new window or tab >>Experimental and PFEM-simulations of residual stresses from turning tests of a cylindrical Ti-6Al-4V shaft
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2018 (English)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 71, p. 144-149Article in journal (Refereed) Published
Abstract [en]

Alloy Ti-6Al-4V is a frequently used material in aero space applications due the high strength and low weight. This material is however often considered as a difficult to machine alloy due to several material properties such as the inherent characteristics of high hot hardness and strength which is causing an increased deformation of the cutting tool during machining. The thermal properties also cause a low thermal diffusion from locally high temperatures in the cutting zone that allows for reaction to the tool material resulting in increased tool wear. Predicting the behavior of machining of this alloy is therefore essential when selecting machining tools or machining strategies. If the surface integrity is predicted, the influence of different machining parameters could be studied using Particle Finite Element (PFEM)-simulations. In this investigation the influence from cutting speed and feed during turning on the residual stresses has been measured using x-ray diffraction and compared to PFEM-simulations. The results showed that cutting speed and feed have great impact on the residual stress state. The measured cutting force showed a strong correlation especially to the cutting feed. The microstructure, observed in SEM, showed highly deformed grains at the surface from the impact of the turning operation and the full width half maximum from the XDR measurements distinguish a clear impact from different cutting speed and feed which differed most for the higher feed rate. The experimental measurements of the residual stresses and the PFEM simulations did however not correlate. The surface stresses as well as the sign of the residuals stresses differed which might be due to the material model used and the assumption of using a Coulomb friction model that might not represent the cutting conditions in the investigated case. © 2018 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
Elsevier B.V., 2018
Keywords
Aluminum alloys; Cutting; High strength alloys; Residual stresses; Space applications; Strength of materials; Ternary alloys; Titanium alloys; Turning; X ray diffraction, Coulomb friction models; Full width half maximum; Inherent characteristics; Machining parameters; PFEM; Residual stress state; Strong correlation; Ti-6 Al-4 V, Cutting tools
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:ri:diva-34900 (URN)10.1016/j.procir.2018.05.087 (DOI)2-s2.0-85051265926 (Scopus ID)
Conference
Conference of 4th CIRP Conference on Surface Integrity, CIRP CSI 2018, 11-13 July, Tianjin, China. Conference Code: 140188
Available from: 2018-08-22 Created: 2018-08-22 Last updated: 2020-01-30Bibliographically approved
Werke, M., Wretland, A., Ottosson, P., Holmberg, J., Machens, M. & Semere, D. (2018). Geometric distortion analysis using a combination of the contour method and machining simulation. In: Procedia CIRP: . Paper presented at 51st CIRP Conference on Manufacturing Systems, CIRP CMS 2018, 16 May 2018 through 18 May 2018 (pp. 1481-1486).
Open this publication in new window or tab >>Geometric distortion analysis using a combination of the contour method and machining simulation
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2018 (English)In: Procedia CIRP, 2018, p. 1481-1486Conference paper, Published paper (Refereed)
Abstract [en]

During machining the material removal releases residual stresses introduced by previous process steps. This causes geometric machining distortions and thereby high rejection rates and costs. By simulating the process chain it is possible to predict this type of distortions. However, this requires advanced material models and accurate process- and material data for the individual processes. In order to simplify the modelling efforts a methodology that combines the contour method with machining simulation is proposed. The methodology is validated for an aerospace component using deep layer removal X-ray diffraction and CMM measurements. The methodology will improve possibilities to reduce machining distortions. © 2018 The Authors.

Keywords
Contour method, Finite Element Analysis, GOM measurements, Machining distortions, Modelling methodology, residual stresses, XRD measurements, Coordinate measuring machines, Finite element method, Advanced materials, Aerospace components, Geometric distortion, Machining distortion, Machining simulation, Manufacture
National Category
Other Natural Sciences
Identifiers
urn:nbn:se:ri:diva-34545 (URN)10.1016/j.procir.2018.03.213 (DOI)2-s2.0-85049577513 (Scopus ID)
Conference
51st CIRP Conference on Manufacturing Systems, CIRP CMS 2018, 16 May 2018 through 18 May 2018
Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2020-01-30Bibliographically approved
Holmberg, J., Palosaari, M., Hosseini, S., Larjosuo, H. & Andersson, P. (2018). Round Robin Study on Residual Stresses Using X-RayDiffraction for Shot-Peened Tool Steel Specimens. In: : . Paper presented at 10th European Conference on Residual Stresses (ECRS10), Leuven, Belgium, 11-14th September, 2018. (pp. 51-55).
Open this publication in new window or tab >>Round Robin Study on Residual Stresses Using X-RayDiffraction for Shot-Peened Tool Steel Specimens
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2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Residual stress measurements using x-ray diffraction is a well established methodused within the industrial and academic community to verify the performance of differentprocesses for metallic materials. The measurement gives an absolute value of the stress statewhich can be used to design and optimize the process route to induce beneficial compressiveresidual stresses and avoid detrimental tensile stresses. Investigating the uncertainty andaccuracy of the measurement system, operator and the material is therefore of high relevanceboth from an industrial and scientific point of view. Round robin testing is an important way toquantify the uncertainties that could affect the quality of the measured results and hence how aprocess is optimized and tuned. Such an investigation allows the operator to understand andreduce variations. Current round robin test includes results from five different laboratories usingcomparable equipments located in Sweden, Finland, Germany and United States. This workfocuses on five shot-peened tool steel specimens produced with identical process settings.Additionally, an investigation of the repeatability of the system, influence of the operator,variations within the specimen, and the long time stability of the specimens has been measured.

Keywords
X-Ray Diffraction, Residual Stress, Round Robin, Measurement System
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36348 (URN)10.21741/9781945291890-9 (DOI)
Conference
10th European Conference on Residual Stresses (ECRS10), Leuven, Belgium, 11-14th September, 2018.
Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2020-01-30Bibliographically approved
Holmberg, J., Wretland, A., Berglund, J. & Beno, T. (2018). Surface integrity after post processing of EDM processed Inconel 718 shaft. The International Journal of Advanced Manufacturing Technology, 95(5-8), 2325-2337
Open this publication in new window or tab >>Surface integrity after post processing of EDM processed Inconel 718 shaft
2018 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 95, no 5-8, p. 2325-2337Article in journal (Refereed) Published
Abstract [en]

Electrical discharge machining (EDM) is considered as an efficient alternative to conventional material removal concepts that allows for much higher material removal rates. However, EDM generates unwanted features such as re-cast layer (RCL), tensile residual stresses and a rough surface. In order to recover the surface integrity, different post processes has been compared: high-pressure water jet (HPWJ), grit blasting (GB) and shot peening (SP). Surface integrity has been evaluated regarding microstructure, residual stresses, chemical content and surface roughness. The results showed that a combination of two post processes is required in order to restore an EDM processed surface of discontinuous islands of RCL. HPWJ was superior for removing RCL closely followed by grit blasting. However, grit blasting showed embedded grit blasting abrasive into the surface. Regarding surface roughness, it was shown that both grit blasting and HPWJ caused a roughening of the surface topography while shot peening generates a comparably smoother surface. All three post processes showed compressive residual stresses in the surface where shot peening generated the highest amplitude and penetration depths. However, the microstructure close to the surface revealed that shot peening had generated cracks parallel to the surface. The results strongly state how important it is to evaluate the surface at each of the different subsequent process steps in order to avoid initiation of cracks. © 2017 The Author(s)

Keywords
Abrasive water jet, EDM, Grit blasting, Inconel 718, Shot peening, Surface integrity, Abrasives, Blasting, Cracks, Electric discharge machining, Electric discharges, Jets, Microstructure, Residual stresses, Surface roughness, Surface topography, Compressive residual stress, Electrical discharge machining, High-pressure water jets, Inconel-718, Tensile residual stress, Fighter aircraft
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33155 (URN)10.1007/s00170-017-1342-6 (DOI)2-s2.0-85034646822 (Scopus ID)
Available from: 2018-01-26 Created: 2018-01-26 Last updated: 2020-01-30Bibliographically approved
Holmberg, J., Lundin, P., Olavisson, J. & Sevim, S. (2017). Non destructive testing of surface characteristics after nitrocarburizing of three different steel grades. In: : . Paper presented at ICBM12 - the 12th International Conference on Barkhausen Noise and Micromagnetic Testing, Dresden, September 24-26..
Open this publication in new window or tab >>Non destructive testing of surface characteristics after nitrocarburizing of three different steel grades
2017 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:ri:diva-31306 (URN)
Conference
ICBM12 - the 12th International Conference on Barkhausen Noise and Micromagnetic Testing, Dresden, September 24-26.
Available from: 2017-09-27 Created: 2017-09-27 Last updated: 2020-01-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2991-2911

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