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Högström, Mats
Publications (6 of 6) Show all publications
Aydin, G., Valiente Bermejo, M. A., Högström, M., Şelte, A., Oikonomou, C. & Andersson, J. (2023). Influence of laser metal deposition process parameters on a precipitation hardening stainless steel. Welding in the World, 67(4), 1067-1080
Open this publication in new window or tab >>Influence of laser metal deposition process parameters on a precipitation hardening stainless steel
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2023 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 67, no 4, p. 1067-1080Article in journal (Refereed) Published
Abstract [en]

The combination of corrosion resistance and mechanical properties of martensitic precipitation hardening stainless steels (MPHSS) makes them well suited for demanding applications in aerospace, high-pressure gas bottles, or in injection molding of corrosive plastics. Directed energy deposition methods and specifically the laser metal deposition process with powder as feedstock (LMDp) have the potential to be applied in the production of such components. It is well-known that the geometrical features of the deposited beads such as aspect ratio and dilution are crucial for process efficiency and deposition quality. Therefore, this work aims at understanding the influence of the process parameters and the resulting microstructure of a MPHSS modified PH 13-8Mo alloy when using LMDp. Design of experiment (DoE) was used to plan and analyze the influence and interaction of the different LMDp process variables in the geometry of the deposits. It was found that height, width, and depth were statistically significantly influenced by speed, while height was also considerably influenced by the powder feeding rate. In terms of laser power, it was the most significant factor for the width and the depth, but it did not significantly affect the height of the beads. The results showed that the as-deposited microstructure of the modified PH 13-8Mo under the LMDp conditions investigated in this work consists of a martensitic matrix with some amount of primary δ ferrite. The presence of a low amount of retained austenite and aluminum-enriched inclusions was confirmed. This work enhances the fundamental process and material understanding of LMDp of the modified PH 13-8Mo alloy as a first stage in the fabrication of additively manufactured components.

Place, publisher, year, edition, pages
Springer, 2023
Keywords
Martensitic precipitation hardening stainless steels, Laser metal deposition, Modifed PH 13-8Mo
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-20968 (URN)10.1007/s40194-023-01478-7 (DOI)000918404500001 ()2-s2.0-85147271322 (Scopus ID)
Note

CC BY 4.0

The Knowledge Foundation funded this research via the TAPERTECH: TAiloring of high-PERformance parts through laser and arc additive manufacturing TECHhnologies project (Reference number: 2018/1890 B20).

Available from: 2023-11-21 Created: 2023-11-21 Last updated: 2024-01-08Bibliographically approved
Högström, M., Fadaei, A., Rahimi, A., Li, P., Igestrand, M., Andersson, J. & Scotti, A. (2023). Proposal and Assessment of a Multiple Cycle-Continuous Cooling Transformation (MC-CCT) Diagram for Wire Arc Additive Manufacturing of Thin Walls. Metals, 13(9), Article ID 1533.
Open this publication in new window or tab >>Proposal and Assessment of a Multiple Cycle-Continuous Cooling Transformation (MC-CCT) Diagram for Wire Arc Additive Manufacturing of Thin Walls
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2023 (English)In: Metals, ISSN 2075-4701, Vol. 13, no 9, article id 1533Article in journal (Refereed) Published
Abstract [en]

Continuous cooling transformation (CCT) diagrams of base metals are common in welding. They can be built using physical or numerical simulations, each with advantages and limitations. However, those are not usual for weld metal, considering its variable composition due to the dilution of the weld into the base metal. Wire Arc Additive Manufacturing (WAAM) is a distinctive casein which the interest in materials comparable with weld composition raises attention to estimating their mechanical properties. Notwithstanding, this concept is still not used in WAAM. Therefore, the aim of this work was to address a methodology to raise MC-CCT (Multiple Cycle ContinuousCooling Transformation) diagrams for WAAM by combining physical and numerical simulations. A high-strength low-alloy steel (HSLA) feedstock (a combination of a wire and a shielding gas) was used as a case study. To keep CCT as representative as possible, the typical multiple thermal cycles for additive manufacturing thin walls were determined and replicated in physical simulations (Gleeble dilatometry). The start and end transformations were determined by the differential linear variation approach for each thermal cycle. Microstructure analyses and hardness were used to characterise the product after the multiple cycles. The same CCT diagram was raised by a commercial numerical simulation package to determine the shape of the transformation curves. A range of austenitic grain sizes was scanned for the curve position matching the experimental results. Combining the experimental data and numerically simulated curves made estimating the final CCT diagram possible.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
T diagram; WAAM; physical simulation; numerical simulation
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-21100 (URN)10.3390/met13091533 (DOI)001075952000001 ()2-s2.0-85172810067 (Scopus ID)
Funder
Knowledge Foundation, 2018/1890 B20
Note

CC-BY 4.0

Funding: The Knowledge Foundation funded this research via the TAPERTECH: TAiloring of high-PERformance parts through laser and arc additive manufacturing TECHhnologies project (Referencenumber: 2018/1890 B20).

Available from: 2023-12-20 Created: 2023-12-20 Last updated: 2024-01-15Bibliographically approved
Baghdadchi, A., Hosseini, V., Valiente Bermejo, M. A., Axelsson, B., Harati, E., Högström, M. & Karlsson, L. (2022). Wire laser metal deposition of 22% Cr duplex stainless steel: as-deposited and heat-treated microstructure and mechanical properties. Journal of Materials Science, 57(21), 9556-9575
Open this publication in new window or tab >>Wire laser metal deposition of 22% Cr duplex stainless steel: as-deposited and heat-treated microstructure and mechanical properties
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2022 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 57, no 21, p. 9556-9575Article in journal (Refereed) Published
Abstract [en]

Duplex stainless steel (DSS) blocks with dimensions of 150 × 70x30 mm3 were fabricated by Laser Metal Deposition with Wire (LMDw). Implementation of a programmable logic control system and the hot-wire technology provided a stable and consistent process producing high-quality and virtually defect-free deposits. Microstructure and mechanical properties were studied for as-deposited (AD) material and when heat-treated (HT) for 1 h at 1100 °C. The AD microstructure was inhomogeneous with highly ferritic areas with nitrides and austenitic regions with fine secondary austenite occurring in a periodic manner. Heat treatment produced a homogenized microstructure, free from nitrides and fine secondary austenite, with balanced ferrite and austenite fractions. Although some nitrogen was lost during LMDw, heat treatment or reheating by subsequent passes in AD allowed the formation of about 50% austenite. Mechanical properties fulfilled common requirements on strength and toughness in both as-deposited and heat-treated conditions achieving the highest strength in AD condition and best toughness and ductility in HT condition. Epitaxial ferrite growth, giving elongated grains along the build direction, resulted in somewhat higher toughness in both AD and HT conditions when cracks propagated perpendicular to the build direction. It was concluded that high-quality components can be produced by LMDw and that deposits can be used in either AD or HT conditions. The findings of this research provide valuable input for the fabrication of high-performance DSS AM components

Keywords
A-stable; Build direction; Defect-free; Heat treated condition; High quality; Hot wires; Laser metal deposition; Microstructures and mechanical properties; Programmable logic control system; Secondary austenite
National Category
Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-18106 (URN)10.1007/s10853-022-06878-6 (DOI)000744401200004 ()2-s2.0-85123120534 (Scopus ID)
Available from: 2022-02-07 Created: 2022-02-07 Last updated: 2024-04-12Bibliographically approved
Baghdadchi, A., Hosseini, V., Valiente Bermejo, M. A., Axelsson, B., Harati, E., Högström, M. & Karlsson, L. (2021). Wire laser metal deposition additive manufacturing of duplex stainless steel components -Development of a systematic methodology. Materials, 14(23), Article ID 7170.
Open this publication in new window or tab >>Wire laser metal deposition additive manufacturing of duplex stainless steel components -Development of a systematic methodology
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2021 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 14, no 23, article id 7170Article in journal (Refereed) Published
Abstract [en]

A systematic four-stage methodology was developed and applied to the Laser Metal Deposition with Wire (LMDw) of a duplex stainless steel (DSS) cylinder > 20 kg. In the four stages, single-bead passes, a single-bead wall, a block, and finally a cylinder were produced. This stepwise approach allowed the development of LMDw process parameters and control systems while the volume of deposited material and the geometrical complexity of components increased. The as-deposited microstructure was inhomogeneous and repetitive, consisting of highly ferritic regions with nitrides and regions with high fractions of austenite. However, there were no cracks or lack of fusion defects; there were only some small pores, and strength and toughness were comparable to those of the corresponding steel grade. A heat treatment for 1 h at 1100 degrees (C) was performed to homogenize the microstructure, remove nitrides, and balance the ferrite and austenite fractions compensating for nitrogen loss occurring during LMDw. The heat treatment increased toughness and ductility and decreased strength, but these still matched steel properties. It was concluded that implementing a systematic methodology with a stepwise increase in the deposited volume and geometrical complexity is a cost-effective way of developing additive manufacturing procedures for the production of significantly sized metallic components.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
Additives; Austenite; Cost effectiveness; Cylinders (shapes); Deposition; Ferrite; Heat treatment; Metals; Microstructure; Nitrides; Stainless steel, Geometrical complexity; Laser metal deposition; Methodology; Microstructure characterization; Process parameters; Stainless steel cylinders; Steel components; Stepwise approach; Systematic methodology; Wires process, 3D printers
National Category
Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-17911 (URN)10.3390/ma14237170 (DOI)000735440900001 ()2-s2.0-85120057286 (Scopus ID)
Funder
Knowledge Foundation, 20170060
Available from: 2021-12-30 Created: 2021-12-30 Last updated: 2024-02-20
Hosseini, V., Högström, M., Hurtig, K., Valiente Bermejo, M. A., Stridh, L.-E. & Karlsson, L. (2019). Wire-arc additive manufacturing of a duplex stainless steel: thermal cycle analysis and microstructure characterization. Welding in the World, 63(4), 975-987
Open this publication in new window or tab >>Wire-arc additive manufacturing of a duplex stainless steel: thermal cycle analysis and microstructure characterization
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2019 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 4, p. 975-987Article in journal (Refereed) Published
Abstract [en]

The evolution of microstructures with thermal cycles was studied for wire-arc additive manufacturing of duplex stainless steel blocks. To produce samples, arc energy of 0.5kJ/mm and interlayer temperature of 150 degrees C were used as low heat input-low interlayer temperature (LHLT) and arc energy of 0.8kJ/mm and interlayer temperature of 250 degrees C as high heat input-high interlayer temperature (HHHT). Thermal cycles were recorded with different thermocouples attached to the substrate as well as the built layers. The microstructure was analyzed using optical and scanning electron microscopy. The results showed that a similar geometry was produced with 14 layers4 beads in each layerfor LHLT and 15 layers3 beads in each layerfor HHHT. Although the number of reheating cycles was higher for LHLT, each layer was reheated for a shorter time at temperatures above 600 degrees C, compared with HHHT. A higher austenite fraction (+8%) was achieved for as-deposited LHLT beads, which experienced faster cooling between 1200 and 800 degrees C. The austenite fraction of the bulk of additively manufactured samples, reheated several times, was quite similar for LHLT and HHHT samples. A higher fraction of secondary phases was found in the HHHT sample due to longer reheating at a high temperature. In conclusion, an acceptable austenite fraction with a low fraction of secondary phases was obtained in the bulk of wire-arc additively manufactured duplex stainless steel samples (35-60%), where higher austenite fractions formed with a larger number of reheating cycles as well as longer reheating at high peak temperatures (800-1200 degrees C).

Keywords
Duplex stainless steels; Additive manufacturing; GMAW; Thermal cycles; Austenite fraction; Secondary phases
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13947 (URN)10.1007/s40194-019-00735-y (DOI)000468518900005 ()2-s2.0-85066099481 (Scopus ID)
Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2020-02-03
Li, P., Hurtig, K., Högström, M., Svensson, L.-E. & Scotti, A. (2018). A contribution to the study of negative polarity in GMA welding. The International Journal of Advanced Manufacturing Technology, 95(5-8), 2543-2553
Open this publication in new window or tab >>A contribution to the study of negative polarity in GMA welding
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2018 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 95, no 5-8, p. 2543-2553Article in journal (Refereed) Published
Abstract [en]

GMAW using the electrode with negative polarity (DCEN) has been frequently suggested as a potential means of increasing production capacity. The objective of this work was to further study the performance of negative polarity in GMAW of carbon steels. In this project phase, bead-on-plate welds were carried out in flat position to assess the effect of different potential shielding gas compositions on bead geometry, finishing and spattering. The characteristics were compared with DCEP at the same current, but depositing the same volume of material per unit of length (more industrial related comparison). The arc length was kept the same by adjusting voltage to reach shortest arcs, yet with suitable non short-circuiting metal transfer mode. An approach to measure bead convexity was also proposed and assessed. The results showed that DCEN is feasible as a means of increasing GMAW production capacity. However, to become DCEN applicable with GMAW, the results suggest an Ar based blend with around 6.5 % of O2 is the most appropriate shielding gas, as much as that there is a demand for a standard electronic controlled power source able to work in constant current mode. 

Keywords
Welding; Production; GMAW; Negative Polarity; Fusion rate; Weld bead geometry
National Category
Other Mechanical Engineering Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-11817 (URN)10.1007/s00170-017-1349-z (DOI)2-s2.0-85035104454 (Scopus ID)
Projects
Maplab
Funder
Region Västra Götaland, RUN 612-0254-15
Note

Funders: Swedish Agency for Economic and Regional Growth, 20200328.

Available from: 2017-11-26 Created: 2017-11-26 Last updated: 2020-04-02Bibliographically approved
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