Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 16) Show all publications
Sundqvist, J. & Samarjy, R. S. (2019). High-speed imaging of droplet behaviour during the CYCLAM drop-deposition technique. Paper presented at 17th Nordic Laser Materials Processing Conference (NOLAMP17), 27-29 August, 2019, Trondheim, Norway. Procedia Manufacturing, 36, 208-215
Open this publication in new window or tab >>High-speed imaging of droplet behaviour during the CYCLAM drop-deposition technique
2019 (English)In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 36, p. 208-215Article in journal (Refereed) Published
Abstract [en]

The material in laser additive manufacturing is traditionally supplied in the form of powder or sometimes wire. A technique called CYCLAM was recently presented which is a fast and direct recycling technique which lowers the number of steps that need to be taken in typical recycling, allowing for a more circular economy. The CYCLAM technique proposes that waste metal is directly recycled through laser cutting or laser ablation of one sheet and the molten droplet is directly deposited onto a new product and can be used for additive manufacturing or cladding. The technique also can also use materials that otherwise are not available as powder or wires. Because of the novelty of the technique, it is still scarcely studied, and many aspects still needs to be understood. This paper focusses on high-speed imaging of the technique to understand the droplet behaviour. The material removal of the feeding sheet was done with Remote Fusion Cutting. Different power levels lead to different drop geometry and flight pattern of the drops where the drops at higher power are pushed further forward. The influence of the laser power on the shape of the deposited track can be seen from cross sections of the cladded track where higher power means that more power is transmitted through the feeding sheet and onto the substrate which creates a smoother surface

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
laser additive manufacturing, circular economy, high-speed imaging, laser cladding, recycling
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-75729 (URN)10.1016/j.promfg.2019.08.027 (DOI)
Conference
17th Nordic Laser Materials Processing Conference (NOLAMP17), 27-29 August, 2019, Trondheim, Norway
Note

Konferensartikel i tidskrift

Available from: 2019-08-28 Created: 2019-08-28 Last updated: 2019-08-28Bibliographically approved
Sundqvist, J., Manninen, T., Heikkinen, H.-P., Anttila, S. & Kaplan, A. F. (2018). Laser surface hardening of 11% Cr ferritic stainless steel and its sensitisation behaviour. Surface & Coatings Technology, 344, 673-679
Open this publication in new window or tab >>Laser surface hardening of 11% Cr ferritic stainless steel and its sensitisation behaviour
Show others...
2018 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 344, p. 673-679Article in journal (Refereed) Published
Abstract [en]

11% Cr ferritic stainless steel conforming to EN 1.4003 standard was surface hardened by a continuous-wave fibre laser beam. Both single-pass and multi-pass laser hardening was investigated. Different laser parameters were compared and their influence on hardness, microstructure, geometry of the hardened zone and sensitisation was investigated, especially for overlapping passes. The experiments showed that a surface hardness which is double that of the base material hardness was obtainable via martensitic phase transformation and high cooling rate, in spite of the low carbon and nitrogen content. This behaviour could be predicted from the chemical composition using the Kaltenhauser Ferrite Factor. Hardening at higher power levels gives more coarse-grained lath martensite but does not increase the hardness. Sensitisation was not a problem in single-pass hardening. However, the production of overlapping tracks could be detrimental to corrosion resistance in 11% Cr steel due to the formation of chromium carbides and nitrides.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Laser surface hardening, Ferritic stainless steel, Sensitisation
National Category
Mechanical Engineering Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-67581 (URN)10.1016/j.surfcoat.2018.04.002 (DOI)000437391300077 ()2-s2.0-85044924333 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-04-06 (andbra)

Available from: 2018-02-09 Created: 2018-02-09 Last updated: 2019-01-15Bibliographically approved
Sundqvist, J., Kim, K., Bang, H.-S., Bang, H. & Kaplan, A. (2018). Numerical simulation of laser preheating of friction stir welding of dissimilar metals. Science and technology of welding and joining, 23(4), 351-356
Open this publication in new window or tab >>Numerical simulation of laser preheating of friction stir welding of dissimilar metals
Show others...
2018 (English)In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 23, no 4, p. 351-356Article in journal (Refereed) Published
Abstract [en]

Friction stir welding, FSW, of harder metal alloys is difficult to perform, like here dissimilar welding of titanium alloy to stainless steel in butt joint configuration. One major limitation is tool wear which can be reduced by preheating with a laser beam. A mathematical model to calculate the tool forces during FSW was developed further. The calculations show that the laser beam reduces forces at the pin and shoulder of the FSW-tool, accompanied by reduced heat generation through the tool. Within its operating limits, the process has low sensitivity on the lateral position of the leading laser beam. The model supports the understanding and optimisation of the complex interaction zone of forces and heat around the FSW-tool.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-66366 (URN)10.1080/13621718.2017.1391936 (DOI)000435470000009 ()2-s2.0-85032491421 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-03-14 (andbra)

Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2018-07-26Bibliographically approved
Sundqvist, J. & Kaplan, A. (2018). Sensitisation behaviour of drop-deposited 11% Cr ferritic stainless steel. Optics and Laser Technology, 487-495
Open this publication in new window or tab >>Sensitisation behaviour of drop-deposited 11% Cr ferritic stainless steel
2018 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, p. 487-495Article in journal (Refereed) Published
Abstract [en]

For low-chromium ferritic stainless steel, a recently developed laser-driven drop-deposition technique enabled the building of three adjacent tracks on a substrate sheet of the same alloy, to study its risk for sensitisation from certain sequences of thermal cycles. The process was recorded by high-speed imaging to understand the drop-deposition mechanisms. Higher beam power resulted in a smoother track. The added layer was fully martensitic, achieving an elevated hardness of 320 HV. For a temperature peak just below austenitisation, the thermal cycle from a subsequent track affected the former track through tempering. Etching revealed a continuous region of ditched grain boundaries around the interface between the melted and heat affected zones. In the melted zone, the network became discontinuous approaching the surface, meaning that the specimen was immune to sensitisation, in contrast to transformation hardening results in the solid state. Additive manufacturing can induce manifold sequences of thermal cycles, but from the here generalized knowledge, strategies against sensitisation can be derived.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Mechanical Engineering Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-70218 (URN)10.1016/j.optlastec.2018.07.031 (DOI)000443664100059 ()2-s2.0-85050526410 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-06 (andbra)

Available from: 2018-08-06 Created: 2018-08-06 Last updated: 2018-10-08Bibliographically approved
Sundqvist, J., Kaplan, A., Shachaf, L. & Kong, C. Y. (2017). Analytical heat conduction modelling for shaped laser beams. Journal of Materials Processing Technology, 247, 48-54
Open this publication in new window or tab >>Analytical heat conduction modelling for shaped laser beams
2017 (English)In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 247, p. 48-54Article in journal (Refereed) Published
Abstract [en]

Conduction mode laser spot welding and laser spot hardening usually employ Gaussian or top-hat-like beam modes. One main requirement of these techniques is the avoidance of overheating in the centre of the laser-material interaction zone. Process flexibility can be improved by spatially and/or temporally shaping the beam, which can enable higher process quality, robustness or speed. A desired spatial beam shape can be achieved by a suitably designed diffractive optical element. However, the prediction of a suitable beam shape for a particular process can be complex. A simplified analytical heat conduction model has been developed that can rapidly calculate the temperature field and cooling behaviour for almost any spatial and temporal beam shape. The potential and limits of the model are demonstrated and discussed by calculating and analysing temperature profiles for several cases of multi-spot welding

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-63056 (URN)10.1016/j.jmatprotec.2017.04.011 (DOI)000403133400006 ()2-s2.0-85018469004 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-05-11 (andbra)

Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2018-07-10Bibliographically approved
Sundqvist, J., Kaplan, A., Shachal, L., Brodsky, A., Kong, C. Y., Blackburn, J., . . . Quintino, L. (2016). Numerical optimization approaches of single-pulse conduction laser welding by beam shape tailoring (ed.). Paper presented at . Optics and lasers in engineering, 79, 48-54
Open this publication in new window or tab >>Numerical optimization approaches of single-pulse conduction laser welding by beam shape tailoring
Show others...
2016 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 79, p. 48-54Article in journal (Refereed) Published
Abstract [en]

While circular laser beams are usually applied in laser welding, for certain applications tailoring of the laser beam shape, e.g. by diffractive optical elements, can optimize the process. A case where overlap conduction mode welding should be used to produce a C-shaped joint was studied. For the dimensions studied in this paper, the weld joint deviated significantly from the C-shape of the single-pulse laser beam. Because of the complex heat flow interactions, the process requires optimization. Three approaches for extracting quantitative indicators for understanding the essential heat flow contributions process and for optimizing the C-shape of the weld and of the laser beam were studied and compared. While integral energy properties through a control volume and temperature gradients at key locations only partially describe the heat flow behaviour, the geometrical properties of the melt pool isotherm proved to be the most reliable method for optimization. While pronouncing the C-ends was not sufficient, an additional enlargement of the laser beam produced the desired C-shaped weld joint. The approach is analysed and the potential for generalization is discussed.

National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-8128 (URN)10.1016/j.optlaseng.2015.12.001 (DOI)000369558900007 ()2-s2.0-84951067602 (Scopus ID)698c7324-1ed7-469f-bfdd-6d2f9ac24b38 (Local ID)698c7324-1ed7-469f-bfdd-6d2f9ac24b38 (Archive number)698c7324-1ed7-469f-bfdd-6d2f9ac24b38 (OAI)
Note
Validerad; 2016; Nivå 2; 20151228 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Kong, C. Y., Bolut, M., Sundqvist, J., Kaplan, A., Assunção, E. & Blackburn, J. (2016). Single-pulse Conduction Limited Laser Welding Using A Diffractive Optical Element. Paper presented at 9th International Conference on Photonic Technologies Proceedings of the LANE 2016 September 19-22, 2016 Fürth, Germany. Physics Procedia, 83, 1217-1222
Open this publication in new window or tab >>Single-pulse Conduction Limited Laser Welding Using A Diffractive Optical Element
Show others...
2016 (English)In: Physics Procedia, ISSN 1875-3892, E-ISSN 1875-3892, Vol. 83, p. 1217-1222Article in journal (Refereed) Published
Abstract [en]

Conduction limited laser welding is commonly used in electronic and battery applications, where a high width-to-depth ratio weld is desirable. A laser beam with Gaussian or top-hat distributions is often used to produce conduction limited spot welds. Both these energy distributions result in a higher proportion of the laser beam energy being introduced towards the centre of the welded spot and consequently, a reduced penetration weld towards the circumference of the beam spot. The use of diffractive optical elements to tailor the energy distribution of the laser beam has been evaluated. An incident laser beam with an energy distribution in the shape of a ring or C-shape was projected onto the material, which results in heat propagating towards the centre, producing a shallow weld with a consistent depth of penetration across the entire overlapped joint. The results confirmed a corresponding thermal model which predicted an even distribution of heat at the joint interface

National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-59732 (URN)10.1016/j.phpro.2016.08.128 (DOI)000387459400132 ()2-s2.0-84994012277 (Scopus ID)
Conference
9th International Conference on Photonic Technologies Proceedings of the LANE 2016 September 19-22, 2016 Fürth, Germany
Note

Konferensartikel i tidskrift

Available from: 2016-10-13 Created: 2016-10-13 Last updated: 2018-07-10Bibliographically approved
Sundqvist, J. (2015). Heat conduction effects during laser welding (ed.). (Licentiate dissertation). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>Heat conduction effects during laser welding
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Since the invention of the laser in 1960, its use has been growing steadily. New laser sources with high beam power and high beam quality provide potential for further growth. High quality beams can be shaped by optical tools, such as scanners or Diffractive Optical Elements, DOE, to almost any beam shape, enabling innovative laser process solutions. For welding in particular, a tailored beam can be used to control the melt pool and to optimise the temperature field and cycle. For example, joining of electrical components like battery cells becomes more common due to the shift to electrical vehicles. This is a field of applications where laser welding with a tailored beam has high potential due to the need of tightly controlled design tolerances or processing temperatures and in turn electrical and mechanical properties. The research presented in the thesis encompasses the heat flow generated from tailored laser beams, the thermal effects on the weld shape and on other quality criteria, the generated residual stress and its influence on fatigue crack propagation. For the sake of simplicity, melt flow was not considered in the calculations, which was discussed, too. The first three papers apply predictive mathematical modelling for the temperature field while the fourth paper experimentally derives the thermally induced residual stress distribution back from measured fatigue crack propagation.Paper I contains a FEM-based numerical heat flow study of a conduction mode laser welding case where a C-shaped overlap joint is desired. The quality criteria demand the welding process to be tightly controlled in terms of laser power and pulse time. Contrary to expectations, the joint geometry can significantly deviate from the laser beam C shape. As a continuation, in Paper II various quantitative indicators were derived and studied as part of the numerical simulation, in order to identify a suitable beam shape and in turn a DOE-design.Paper III presents a semi-analytical mathematical model that was developed for the heat flow in pulsed conduction mode welding for spatially and temporally shaped laser beams. As an alternative to FEM, the model is fast due to its analytical nature, which enables iterative beam shape optimization and DOE-design. By studying different beam shapes and the induced temperature fields, the potential and limits of the model were demonstrated and discussed. Paper IV is a study on residual stress that is thermally induced during the heating and cooling cycle of laser keyhole welding. Acceleration measurement of the crack propagating across the weld during fatigue testing turned out to be a suitable method to derive the residual stress distribution along the crack, including its alteration during the cracking. Comparisons with FEM-based stress analysis provide a link back to the temperature field induced by the laser, which enables optimization, e.g. by beam shaping.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2015
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-17902 (URN)5c914494-97dc-4788-ae29-146b4cdf1062 (Local ID)978-91-7583-424-5 (ISBN)978-91-7583-425-2 (ISBN)5c914494-97dc-4788-ae29-146b4cdf1062 (Archive number)5c914494-97dc-4788-ae29-146b4cdf1062 (OAI)
Note
Godkänd; 2015; 20150911 (jessun); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Jesper Sundqvist Ämne: Produktionsutveckling/Manufacturing System Engineering Uppsats: Heat Conduction Effects During Laser Welding Examinator: Professor Alexander Kaplan, Institutionen för teknikvetenskap och matematik, Avdelning: Produkt- och produktionsutveckling, Luleå tekniska universitet Diskutant: Professor Lars Pejryd, Örebro universitet, Örebro Tid: Tisdag 10 november, 2015 kl 12.30 Plats: E632, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Sundqvist, J., Kaplan, A., Kong, C. Y., Blackburn, J., Assuncao, E. & Quintino, L. (2015). Heat conduction modelling to optimize the laser beam profile for pulsed conduction mode welding (ed.). Paper presented at International Congress on Laser Advanced Materials Processing : 26/05/2015 - 29/05/2015. Paper presented at International Congress on Laser Advanced Materials Processing : 26/05/2015 - 29/05/2015.
Open this publication in new window or tab >>Heat conduction modelling to optimize the laser beam profile for pulsed conduction mode welding
Show others...
2015 (English)Conference paper, Oral presentation only (Refereed)
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-38511 (URN)cefc1742-eda5-43e5-ace2-9f09fbd038c2 (Local ID)cefc1742-eda5-43e5-ace2-9f09fbd038c2 (Archive number)cefc1742-eda5-43e5-ace2-9f09fbd038c2 (OAI)
Conference
International Congress on Laser Advanced Materials Processing : 26/05/2015 - 29/05/2015
Note
Godkänd; 2015; 20151117 (jessun)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Sundqvist, J., Kaplan, A., Granström, J., Sundin, K.-G., Keskitalo, M., Mäntyjärvi, K. & Ren, X. (2015). Identifying residual stresses in laser welds by fatigue crack growth acceleration measurement (ed.). Paper presented at . Journal of laser applications, 27(4), Article ID 42002.
Open this publication in new window or tab >>Identifying residual stresses in laser welds by fatigue crack growth acceleration measurement
Show others...
2015 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 27, no 4, article id 42002Article in journal (Refereed) Published
Abstract [en]

During laser welding, residual stresses are thermally induced. They can have strong impact on the fatigue behavior and fatigue life. A standardized measurement method for the fatigue crack growth rate was expanded to identify residual stress along the cracking path. The second derivative of the measured crack opening and in turn the crack acceleration corresponded well with distinct acceleration maxima and minima and accordingly with tensile and compressive stress, as was basically proven by numerical simulation. The method is simple and extendable. It provides valuable information, as was demonstrated for various situations.

National Category
Manufacturing, Surface and Joining Technology Applied Mechanics
Research subject
Manufacturing Systems Engineering; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-10852 (URN)10.2351/1.4923472 (DOI)000362569000002 ()2-s2.0-84936882579 (Scopus ID)9bb76bdd-9c0b-4c71-8a47-fc833d81bb4e (Local ID)9bb76bdd-9c0b-4c71-8a47-fc833d81bb4e (Archive number)9bb76bdd-9c0b-4c71-8a47-fc833d81bb4e (OAI)
Note
Validerad; 2015; Nivå 2; 20151102 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9010-1555

Search in DiVA

Show all publications