Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 78) Show all publications
Dahat, S., Hurtig, K., Andersson, J. & Scotti, A. (2020). A Methodology to Parameterize Wire + Arc Additive Manufacturing: A Case Study for Wall Quality Analysis. Journal of Manufacturing and Materials Processing, 4(1), Article ID 14.
Open this publication in new window or tab >>A Methodology to Parameterize Wire + Arc Additive Manufacturing: A Case Study for Wall Quality Analysis
2020 (English)In: Journal of Manufacturing and Materials Processing, Vol. 4, no 1, article id 14Article in journal (Refereed) Published
Abstract [en]

The objective of this work was the development of a methodology to parametrize wire + arc additive manufacturing (WAAM), aiming dimension repeatability, and tolerances. Parametrization of WAAM is a difficult task, because multiple parameters are involved and parameters are inter-dependent on each other, making overall process complex. An approach to study WAAM would be through operational maps. The choice of current (Im) and travel speed (TS) for the desirable layer width (LW) determines a parametrization that leads to either more material or less material to be removed in post-operations, which is case study chosen for this work. The work development had four stages. First stage, named ‘mock design’, had the objective of visualizing the expected map and reduce further number of experiments. At the second stage, ‘pre-requisite for realistic operational map’, the objective was to determine the operating limits of TS and Im with the chosen consumables and equipment. Within the ‘realistic operational map’ stage, a design for the experiments was applied to cover a parametric area (working envelope) already defined in the previous stage and long and tall walls were additively manufactured. Actual values of LW (external and effective layer width) were measured and an actual operating envelope was reached. According to the geometry-oriented case study, a surface waviness index (SWindex) was defined, determined, and overlapped in the envelope. It was observed that the walls with parameters near the travel speed limits presented higher SWindex. This operational map was further validated (fourth stage) by selecting a target LW and finding corresponding three parametric set (covering the whole range of operational map) to produce walls on which geometry characterization was carried out. After geometry characterization, obtained LW was compared with the target LW (the maximum values were very tied, with deviations from +0.3 to 0.5 mm), with a SWindex deviation at the order of 0.05. Both results evidence high reproductivity of the process, validating the proposed methodology to parametrize WAAM.

Keywords
CMT, GMAW, operational map, parameterization, printing quality, WAAM
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hv:diva-15013 (URN)10.3390/jmmp4010014 (DOI)
Funder
Knowledge Foundation
Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-02-24
Hanning, F., Khan, A. K., Andersson, J. & Ojo, O. (2020). Advanced microstructural characterisation of cast ATI 718 Plus-effect of homogenisation heat treatments on secondary phases and repair welding behaviour. Welding in the World, 64(3), 523-533
Open this publication in new window or tab >>Advanced microstructural characterisation of cast ATI 718 Plus-effect of homogenisation heat treatments on secondary phases and repair welding behaviour
2020 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 64, no 3, p. 523-533Article in journal (Refereed) Epub ahead of print
Abstract [en]

The influence of base metal conditions on the weld cracking behaviour of cast ATI 718Plus® is investigated by comparing 4 h and 24 h dwell time pseudo-hip homogenisation heat treatments at 1120, 1160 and 1190 °C with the as-cast microstructure. Scanning electron microscopy (SEM), X-ray diffraction (XRD) on electrolytically extracted powder and transmission electron microscopy (TEM) were used to identify Nb-rich secondary phases in interdendritic areas as the C14 Laves phase and Nb(Ti) MC-type carbides. All homogenisation heat treatments but the 1120 °C 4-h condition dissolve the Laves phase. A repair welding operation was simulated by linear groove multi-pass manual gas tungsten arc welding (GTAW). The Laves phase containing microstructures resulted in lower total crack length for heat affected zone cracking. Constitutional liquation of Nb(Ti) MC-type carbides is observed as a liquation mechanism in Laves-free microstructure, while thick liquid film formation due to the Laves eutectic melting could reduce the formation of weld cracks in microstructures containing the Laves phase.

Keywords
Carbides; Cladding (coating); Crack initiation; Gas metal arc welding; Gas welding; Heat affected zone; Heat treatment; High resolution transmission electron microscopy; Liquid films; Microstructure; Nickel alloys; Repair; Scanning electron microscopy; Weldability, As cast microstructure; Constitutional liquation; Formation of weld; Gas tungsten arc welding; GTA welding; Heat affected zone crackings; Interdendritic areas; Microstructural characterisation, Thallium alloys
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-14997 (URN)10.1007/s40194-020-00851-0 (DOI)000519395500010 ()2-s2.0-85078321984 (Scopus ID)
Funder
Swedish Energy Agency
Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-04-02Bibliographically approved
Karimi Neghlani, P., Schnur, C., Sadeghi, E. & Andersson, J. (2020). Contour design to improve topographical and microstructural characteristics of Alloy 718 manufactured by electron beam-powder bed fusion technique. Additive Manufacturing, 32, Article ID 101014.
Open this publication in new window or tab >>Contour design to improve topographical and microstructural characteristics of Alloy 718 manufactured by electron beam-powder bed fusion technique
2020 (English)In: Additive Manufacturing, ISSN 2214-8604, Vol. 32, article id 101014Article in journal (Refereed) Published
Abstract [en]

Additive manufacturing (AM) processes are being frequently used in industry as they allow the manufacture ofcomplex parts with reduced lead times. Electron beam-powder bed fusion (EB-PBF) as an AM technology isknown for its near-net-shape production capacity with low residual stress. However, the surface quality andgeometrical accuracy of the manufactured parts are major obstacles for the wider industrial adoption of thistechnology, especially when enhanced mechanical performance is taken into consideration. Identifying theorigins of surface features such as satellite particles and sharp valleys on the parts manufactured by EB-PBF isimportant for a better understanding of the process and its capability. Moreover, understanding the influence ofthe contour melting strategy, by altering process parameters, on the surface roughness of the parts and thenumber of near-surface defects is highly critical. In this study, processing parameters of the EB-PBF techniquesuch as scanning speed, beam current, focus offset, and number of contours (one or two) with the linear meltingstrategy were investigated. A sample manufactured using Arcam-recommended process parameters (threecontours with the spot melting strategy) was used as a reference. For the samples with one contour, the scanningspeed had the greatest effect on the arithmetical mean height (Sa), and for the samples with two contours, thebeam current and focus offset had the greatest effect. For the samples with two contours, a lower focus offset andlower scan speed (at a higher beam current) resulted in a lower Sa; however, increasing the scan speed for thesamples with one contour decreased Sa. In general, the samples with two contours provided a lower Sa (∼22 %)but with slightly higher porosity (∼8 %) compared to the samples with one contour. Fewer defects were detected with a lower scanning speed and higher beam current. The number of defects and the Sa value for thesamples with two contours manufactured using the linear melting strategy were ∼85 % and 16 %, respectively,lower than those of the reference samples manufactured using the spot melting strategy.

Keywords
3D printers; Additives; Electron beams; Scanning; Speed; Surface defects; Surface properties; Surface roughness, Alloy 718; Geometrical accuracy; Linear and spot melting strategies; Mechanical performance; Micro-structural characteristics; Near-surface defects; Powder bed; Processing parameters, Melting
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-14993 (URN)10.1016/j.addma.2019.101014 (DOI)2-s2.0-85078915522 (Scopus ID)
Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-02-24Bibliographically approved
Karimi Neghlani, P., Sadeghi, E., Ålgårdh, J., Harlin, P. & Andersson, J. (2020). Effect of build location on microstructural characteristics and corrosion behavior of EB-PBF built Alloy 718. The International Journal of Advanced Manufacturing Technology, 106(7-8), 3597-3607
Open this publication in new window or tab >>Effect of build location on microstructural characteristics and corrosion behavior of EB-PBF built Alloy 718
Show others...
2020 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 106, no 7-8, p. 3597-3607Article in journal (Refereed) Published
Abstract [en]

Electron beam-powder bed fusion (EB-PBF), a high-temperature additive manufacturing (AM) technique, shows great promise in the production of high-quality metallic parts in different applications such as the aerospace industry. To achieve a higher build efficiency, it is ideal to build multiple parts together with as low spacing as possible between the respective parts. In the EB-PBF technique, there are many unknown variations in microstructural characteristics and functional performance that could be induced as a result of the location of the parts on the build plate, gaps between the parts and part geometry, etc. In the present study, the variations in the microstructure and corrosion performance as a function of the parts location on the build plate in the EB-PBF process were investigated. The microstructural features were correlated with the thermal history of the samples built in different locations on the build plate, including exterior (the outermost), middle (between the outermost and innermost), and interior (the innermost) regions. The cubic coupons located in the exterior regions showed increased level (~ 20 %) of defects (mainly in the form of shrinkage pores) and lower level (~ 30-35 %) of Nb-rich phase fraction due to their higher cooling rates compared to the interior and middle samples. Electrochemical investigations showed that the location indirectly had a substantial influence on the corrosion behavior, verified by a significant increase in polarization resistance (Rp) from the exterior (2.1 ± 0.3 kΩ.cm2) to interior regions (39.2 ± 4.1 kΩ.cm2). © 2020, The Author(s).

Keywords
3D printers; Additives; Aerospace industry; Corrosion; Corrosive effects; Electron beams; Hardness; High temperature applications, Alloy 718; Electrochemical investigations; Functional performance; Micro-structural characteristics; Micro-structural characterization; Microstructural features; Polarization resistances; Powder bed, Location
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hv:diva-15004 (URN)10.1007/s00170-019-04859-9 (DOI)000511506500069 ()2-s2.0-85077549789 (Scopus ID)
Funder
Knowledge FoundationEuropean Regional Development Fund (ERDF)
Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-02-27
Sreekanth, S., Hurtig, K., Joshi, S. V., Andersson, J. & Ghassemali, E. (2020). Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718. Metals, 10(1), 01-16, Article ID 96.
Open this publication in new window or tab >>Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 718
Show others...
2020 (English)In: Metals, E-ISSN 2075-4701, Vol. 10, no 1, p. 01-16, article id 96Article in journal (Refereed) Published
Abstract [en]

The effect of three important process parameters, namely laser power, scanning speed and laser stand-off distance on the deposit geometry, microstructure and segregation characteristics in direct energy deposited alloy 718 specimens has been studied. Laser power and laser stand-off distance were found to notably affect the width and depth of the deposit, while the scanning speed influenced the deposit height. An increase in specific energy conditions (between 0.5 J/mm2 and 1.0 J/mm2) increased the total area of deposit yielding varied grain morphologies and precipitation behaviors which were comprehensively analyzed. A deposit comprising three distinct zones, namely the top, middle and bottom regions, categorized based on the distinct microstructural features formed on account of variation in local solidification conditions. Nb-rich eutectics preferentially segregated in the top region of the deposit (5.4–9.6% area fraction, Af) which predominantly consisted of an equiaxed grain structure, as compared to the middle (1.5–5.7% Af) and the bottom regions (2.6–4.5% Af), where columnar dendritic morphology was observed. High scan speed was more effective in reducing the area fraction of Nb-rich phases in the top and middle regions of the deposit. The <100> crystallographic direction was observed to be the preferred growth direction of columnar grains while equiaxed grains had a random orientation.

Keywords
laser metal deposition (LMD); columnar dendritic morphology; constitutional supercooling; columnar to equiaxed transition (CET); high deposition rate
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-14922 (URN)10.3390/met10010096 (DOI)000516827800096 ()
Available from: 2020-01-29 Created: 2020-01-29 Last updated: 2020-03-27Bibliographically approved
Andersson, J. (2020). Welding metallurgy and weldability of superalloys. Metals, 10(1), Article ID 143.
Open this publication in new window or tab >>Welding metallurgy and weldability of superalloys
2020 (English)In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 143Article in journal, Editorial material (Refereed) Published
Place, publisher, year, edition, pages
MDPI AG, 2020
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hv:diva-14995 (URN)10.3390/met10010143 (DOI)000516827800143 ()2-s2.0-85078407195 (Scopus ID)
Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-03-27
Asala, G., Andersson, J. & Ojo, O. A. (2019). A study of the dynamic impact behaviour of IN 718 and ATI 718Plus® superalloys. Philosophical Magazine, 99(4), 419-437
Open this publication in new window or tab >>A study of the dynamic impact behaviour of IN 718 and ATI 718Plus® superalloys
2019 (English)In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 99, no 4, p. 419-437Article in journal (Refereed) Published
Abstract [en]

The dynamic impact response of IN 718 and ATI 718Plus®, in both the solution heat treated and age-hardened conditions, were investigated at different deformation temperatures and strain rates using a direct impact Hopkinson pressure bar. Analyses of the results provide a vital but previously not reported information that the ATI 718Plus® offers a higher resistance to damage during high strain rate ballistic impact deformation compared to the most widely used Iron-nickel based superalloy, Inconel 718. ATI 718Plus® showed higher strain hardening and strain rate sensitivity, in both heat treatment conditions, than IN 718. The difference in the deformation behaviour of both alloys, in the annealed condition, is attributable to the compositional modification in ATI 718Plus® which has been reported to lower its stacking fault energy and increases the tendency for deformation twinning. However, in the age-hardened condition, the difference is believed to be related to the disparity in the operative strengthening mechanism, of the precipitates present in both alloys. Furthermore, a higher susceptibility to strain location and the formation of adiabatic shear band, in aged IN 718, is attributable to the stronger temperature-softening characteristics observed in the alloy and to the limited strain hardening tendency under dynamic impact loading. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

Keywords
Deformation, Dynamics, Iron alloys, Mechanical properties, Nickel alloys, Scanning electron microscopy, Shear bands, Strain hardening, Superalloys, Transmission electron microscopy, Twinning, Compositional modification, Damage, Deformation properties, Deformation temperatures, Heat treatment conditions, Stacking fault energies, Strain hardening and strain rate sensitivity, Strengthening mechanisms, Strain rate
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13177 (URN)10.1080/14786435.2018.1540891 (DOI)000455480300002 ()2-s2.0-85056162234 (Scopus ID)
Note

Published online: 07 Nov 2018

Funder: Natural Sciences and Engineering Research Council of Canada

Available from: 2018-12-03 Created: 2018-12-03 Last updated: 2020-02-04Bibliographically approved
Asala, G., Andersson, J. & Ojo, O. A. (2019). Analysis and constitutive modelling of high strain rate deformation behaviour of wire-arc additive-manufactured ATI 718Plus superalloy. The International Journal of Advanced Manufacturing Technology, 103(1-4), 1419-1431
Open this publication in new window or tab >>Analysis and constitutive modelling of high strain rate deformation behaviour of wire-arc additive-manufactured ATI 718Plus superalloy
2019 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 103, no 1-4, p. 1419-1431Article in journal (Refereed) Published
Abstract [en]

A fundamental prerequisite for obtaining realistic finite element simulation of machining processes, which has become a key machinability assessment for metals and alloys, is the establishment of a reliable material model. To obtain the constitutive model for wire-arc additive-manufactured ATI 718Plus, Hopkinson pressure bar is used to characterise the flow stress of the alloy over a wide range of temperatures and strain rates. Experiment results show that the deformation behaviours of as-deposited ATI 718Plus superalloy are influenced by the applied strain rate, test temperature and strain. Post-deformation microstructures show localised deformation within the deposit, which is attributable to the heterogeneous distribution of the strengthening precipitates in as-deposited ATI 718Plus. Furthermore, cracks are observed to be preferentially initiated at the brittle eutectic solidification constituents within the localised band. Constitutive models, based on the strain-compensated Arrhenius-type model and the modified Johnson-Cook model, are developed for the deposit based on experimental data. Standard statistical parameters, correlation coefficient (R), root-mean-square error (RMSE) and average absolute relative error (AARE) are used to assess the reliability of the models. The results show that the modified Johnson-Cook model has better reliability in predicting the dynamic flow stress of wire-arc-deposited ATI 718Plus superalloy. © 2019, Springer-Verlag London Ltd., part of Springer Nature.

Keywords
3D printers, Additives, Constitutive models, Deformation, Deposits, Machinability, Machining, Mean square error, Metallurgy, Nickel alloys, Plastic flow, Solidification, Superalloys, Wire, Deformation microstructure, Finite element simulations, Heterogeneous distributions, High strain rate deformation, High strain rates, Machinability assessment, Ni-based superalloys, Root mean square errors, Strain rate
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13848 (URN)10.1007/s00170-019-03616-2 (DOI)000475921300105 ()2-s2.0-85064476747 (Scopus ID)
Note

Funders; Natural Sciences and Engineering Research Council of Canada

Available from: 2019-05-24 Created: 2019-05-24 Last updated: 2020-02-03Bibliographically approved
Karimi Neghlani, P., Sadeghi, E., Ålgårdh, J. & Andersson, J. (2019). EBM-manufactured single tracks of Alloy 718: Influence of energy input and focus offset on geometrical and microstructural characteristics. Materials Characterization, 148, 88-99
Open this publication in new window or tab >>EBM-manufactured single tracks of Alloy 718: Influence of energy input and focus offset on geometrical and microstructural characteristics
2019 (English)In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 148, p. 88-99Article in journal (Refereed) Published
Abstract [en]

Electron beam melting-powder bed fusion (EBM-PBF) is an additive manufacturing process, which is able to produce parts in layer-by-layer fashion from a 3D model data. Currently application of this technology in parts manufacturing with high geometrical complexity has acquired growing interest in industry. To recommend the EBM process into industry for manufacturing parts, improved mechanical properties of final part must be obtained. Such properties highly depend on individual single melted track and single layer. In EBM, interactions between the electron beam, powder, and solid underlying layer affect the geometrical (e.g., re-melt depth, track width, contact angle, and track height) and microstructural (e.g., grain structure, and primary dendrite arm spacing) characteristics of the melted tracks. The core of the present research was to explore the influence of linear energy input parameters in terms of beam scanning speed, beam current as well as focus offset and their interactions on the geometry and microstructure of EBM-manufactured single tracks of Alloy 718. Increased scanning speed led to lower linear energy input values (<0.9 J/mm) in an specific range of the focus offset (0–10 mA) which resulted in instability, and discontinuity of the single tracks as well as balling effect. Decreasing the scanning speed and increasing the beam current resulted in higher melt pool depth and width. By statistical evaluations, the most influencing parameters on the geometrical features were primarily the scanning speed, and secondly the beam current. Primary dendrite arm spacing (PDAS) slightly decreased by increasing the scanning speed using lower beam current values as the linear energy input decreased. By increasing the linear energy input, the chance of more equiaxed grain formation was high, however, at lower linear energy input, mainly columnar grains were observed. The lower focus offset values resulted in more uniform grains along the 〈001〉 crystallographic direction. © 2018 Elsevier Inc. 

Keywords
3D printers; Contact angle; Dendrites (metallography); Design of experiments; Electron beam melting; Electron beams; Scanning; Speed, Alloy 718; Geometrical characteristics; Powder bed; Single-tracks; Solidified microstructures, Geometry
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13365 (URN)10.1016/j.matchar.2018.11.033 (DOI)000458228100011 ()2-s2.0-85058512738 (Scopus ID)
Funder
European Regional Development Fund (ERDF)Knowledge Foundation
Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2020-02-04Bibliographically approved
Singh, S. & Andersson, J. (2019). Heat-Affected-Zone Liquation Cracking in Welded Cast Haynes® 282®. Metals, 10(1), Article ID 29.
Open this publication in new window or tab >>Heat-Affected-Zone Liquation Cracking in Welded Cast Haynes® 282®
2019 (English)In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 29Article in journal (Refereed) Published
Abstract [en]

Varestraint weldability testing and Gleeble thermomechanical simulation of the newly developed cast form of Haynes® 282® were performed to understand how heat-affected-zone (HAZ) liquation cracking is influenced by different preweld heat treatments. In contrast to common understanding, cracking susceptibility did not improve with a higher degree of homogenization achieved at a higher heat-treatment temperature. Heat treatments with a 4 h dwell time at 1120 °C and 1160 °C exhibited low cracking sensitivity, whereas by increasing the temperature to 1190 °C, the cracking was exacerbated. Nanosecond ion mass spectrometry analysis was done to characterize B segregation at grain boundaries that the 1190 °C heat treatment indicated to be liberated from the dissolution of C–B rich precipitates

Place, publisher, year, edition, pages
MDPI, 2019
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hv:diva-15012 (URN)10.3390/met10010029 (DOI)000516827800029 ()2-s2.0-85077358389 (Scopus ID)
Funder
European Regional Development Fund (ERDF)
Note

Funders; GKN

Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-03-27
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9065-0741

Search in DiVA

Show all publications