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Evaluation of a temperature measurement method developed for laser metal deposition
University West, Department of Engineering Science, Division of Manufacturing Processes. (PTW)ORCID iD: 0000-0002-1472-5489
University West, Department of Engineering Science, Division of Manufacturing Processes. (PTW)ORCID iD: 0000-0001-9065-0741
University West, Department of Engineering Science, Division of Manufacturing Processes. (PTW)ORCID iD: 0000-0003-2560-0531
2017 (English)In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 22, no 1, p. 1-6Article in journal (Refereed) Published
Abstract [en]

Measuring temperatures in the material during laser metal deposition (LMD) has an inherent challenge caused by the laser. When thermocouples are radiated by the high intensity laser light overheating occurs which causes the thermocouple to fail. Another identified difficulty is that when the laser passes a thermocouple, emitted light heats the thermocouple to a higher temperature than the material actually experience. In order to cope with these challenges, a method of measuring temperatures during LMD of materials using protective sheets has been developed and evaluated as presented in this paper. The method has substantially decreased the risk of destroying the thermocouple wires during laser deposition. Measurements using 10 mm2 and 100 mm2 protective sheets have been compared. These measurements show small variations in the cooling time (∼0.1 s from 850°C to 500°C) between the small and large protective sheets which indicate a negligible effect on the temperature measurement. © 2016 Institute of Materials, Minerals and Mining.

Place, publisher, year, edition, pages
2017. Vol. 22, no 1, p. 1-6
Keywords [en]
Laser metal deposition, additive manufacturing, powder, Alloy 718, temperature measurement
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
URN: urn:nbn:se:hv:diva-8803DOI: 10.1080/13621718.2016.1169363ISI: 000387910300001Scopus ID: 2-s2.0-84978471771OAI: oai:DiVA.org:hv-8803DiVA, id: diva2:882455
Funder
Swedish National Space Board
Note

Ingår i lic.avhandling

Available from: 2015-12-15 Created: 2015-12-15 Last updated: 2023-04-05Bibliographically approved
In thesis
1. Laser Metal Deposition using Alloy 718 Powder: Influence of Process Parameters on Material Characteristics
Open this publication in new window or tab >>Laser Metal Deposition using Alloy 718 Powder: Influence of Process Parameters on Material Characteristics
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Additive manufacturing (AM) is a general name used for manufacturing methods which have the capabilities of producing components directly from 3D computeraided design (CAD) data by adding material layer-by-layer until a final componentis achieved. Included here are powder bed technologies, laminated object manufacturing and deposition technologies. The latter technology is used in this study. Laser Metal Powder Deposition (LMPD) is an AM method which builds components by fusing metallic powder together with a metallic substrate, using a laser as energy source. The powder is supplied to the melt-pool, which is created by the laser, through a powder nozzle which can be lateral or coaxial. Both the powder nozzle and laser are mounted on a guiding system, normally a computer numerical control (CNC) machine or a robot. LMPD has lately gained attentionas a manufacturing method which can add features to semi-finished components or as a repair method. LMPD introduce a low heat input compared to conventional arc welding methods and is therefore well suited in, for instance, repair of sensitive parts where too much heating compromises the integrity of the part. The main part of this study has been focused on correlating the main process parameters to effects found in the material which in this project is the superalloy Alloy 718. It has been found that the most influential process parameters are the laser power, scanning speed, powder feeding rate and powder standoff distance.These process parameters have a significant effect on the temperature history ofthe material which, among others, affects the grain structure, phase transformation, and cracking susceptibility of the material. To further understand the effects found in the material, temperature measurements has been conducted using a temperature measurement method developed and evaluated in this project. This method utilizes a thin stainless steel sheet to shield the thermocouple from the laser light. This has proved to reduce the influence of the laser energy absorbed by the thermocouples.

Place, publisher, year, edition, pages
Trollhättan: University West, 2017. p. 104
Series
PhD Thesis: University West ; 12
Keywords
Additive manufacturing; Laser metal deposition; Powder; Superalloy; Material characterization
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-11842 (URN)978-91-87531-68-2 (ISBN)978-91-87531-67-5 (ISBN)
Public defence
2017-12-18, F104, Trollhättan, 10:00 (English)
Opponent
Supervisors
Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2017-11-29Bibliographically approved
2. Additive Manufacturing using Alloy 718 Powder: Influence of Laser Metal Deposition Process Parameters on Microstructural Characteristics
Open this publication in new window or tab >>Additive Manufacturing using Alloy 718 Powder: Influence of Laser Metal Deposition Process Parameters on Microstructural Characteristics
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Additive manufacturing (AM) is a general name used for production methodswhich have the capabilities of producing components directly from 3D computeraided design (CAD) data by adding material layer-by-layer until a final component is achieved. Included here are powder bed technologies, laminated object manufacturing and deposition technologies. The latter technology is used in this study.Laser metal deposition using powder as an additive (LMD-p) is an AM processwhich uses a multi-axis computer numerical control (CNC) machine or robot toguide the laser beam and powder nozzle over the deposition surface. Thecomponent is built by depositing adjacent beads layer by layer until thecomponent is completed. LMD-p has lately gained attention as a manufacturing method which can add features to semi-finished components or as a repair method. LMD-p introduce a low heat input compared to arc welding methods and is therefore well suited in applications where a low heat input is of an essence. For instance, in repair of sensitive parts where too much heating compromises the integrity of the part.The main part of this study has been focused on correlating the main processparameters to effects found in the material which in this project is the superalloy Alloy 718. It has been found that the most influential process parameters are the laser power, scanning speed, powder feeding rate and powder standoff distance and that these parameters has a significant effect on the dimensionalcharacteristics of the material such as height and width of a single deposit as wellas the straightness of the top surface and the penetration depth.To further understand the effects found in the material, temperaturemeasurements has been conducted using a temperature measurement methoddeveloped and evaluated in this project. This method utilizes a thin stainless steel sheet to shield the thermocouple from the laser light. This has proved to reduce the influence of the emitted laser light on the thermocouples.

Place, publisher, year, edition, pages
Trollhättan: University West, 2015. p. 97
Series
Licentiate Thesis: University West ; 8
Keywords
Additive manufacturing, Laser metal deposition, powder, superalloy
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-8796 (URN)978-91-87531-24-8 (ISBN)978-91-87531-25-5 (ISBN)
Opponent
Supervisors
Available from: 2015-12-15 Created: 2015-12-14 Last updated: 2023-04-05Bibliographically approved

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Segerstark, AndreasAndersson, JoelSvensson, Lars-Erik

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