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Sandberg, Fredrik
Publications (9 of 9) Show all publications
Al-Saadi, M., Sandberg, F., Hulme-Smith, C. & Jönsson, P. (2021). Modelling of strengthening mechanisms in wrought nickel-based 825 alloy subjected to solution annealing. Metals, 11(5), 771-20
Open this publication in new window or tab >>Modelling of strengthening mechanisms in wrought nickel-based 825 alloy subjected to solution annealing
2021 (English)In: Metals, ISSN 2075-4701, Vol. 11, no 5, p. 771-20Article in journal (Refereed) Published
Abstract [en]

Wrought nickel‐based Alloy 825 is widely used in the oil and gas industries, attributed toits high strength at temperatures up to 540 °C. However, differences in mechanical properties arisein finished components due to variations in both grain size and dislocation density. Numerous ex‐perimental studies of the strengthening mechanisms have been reported and many models havebeen developed to predict strengthening under thermomechanical processing. However, there aredebates surrounding some fundamental issues in modeling and the interpretation of experimentalobservations. Therefore, it is important to understand the evolution of strain within the materialduring the hot‐forging process. In addition, there is a lack of research around the behavior duringhot deformation and subsequent stabilization of Alloy 825. This article investigates the origin of thisstrength and considers a variety of strengthening mechanisms, resulting in a quantitative predictionof the contribution of each mechanism. The alloy is processed with a total forging strain of 0.45, 0.65,or 0.9, and subsequent annealing at a temperature of 950 °C, reflecting commercial practice. Themicrostructure after annealing is similar to that before annealing, suggesting that static recovery isdominant at this temperature. The maximum yield strength and ultimate tensile strength were348 MPa and 618 MPa, respectively, obtained after forging to a true strain of 0.9, with a ductility of40%. The majority of strengthening was attributed to grain refinement, the dislocation densities thatarise due to the large forging strain deformation, and solid solution strengthening. Precipitatestrengthening was also quantified using the Brown and Ham modification of the Orowan bowingmodel. The results of yield strength calculations are in excellent agreement with experimental data,with less than 1% difference. The interfacial energy of Ti(C,N) in the face‐centered cubic matrix of. These results can bethe current alloy has been assessed for the first time, with a value of 0.8 mJm−2used by future researchers and industry to predict the strength of Alloy 825 and similar alloys, es‐pecially after hot‐forging.

Place, publisher, year, edition, pages
Basel, Switzerland.: MDPI AG, 2021
Keywords
Alloy 825; strain level; strength properties; annealing; strengthening mechanisms
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-295470 (URN)10.3390/met11050771 (DOI)000662504700001 ()2-s2.0-85105421222 (Scopus ID)
Note

QC 20220503

Available from: 2021-05-21 Created: 2021-05-21 Last updated: 2022-06-25Bibliographically approved
Al-Saadi, M., Sandberg, F., Hulme-Smith, C., Karasev, A. & Jönsson, P. (2019). A study of the static recrystallization behaviour of cast Alloy 825 after hot-compressions. In: Journal of Physics: Conference Series: . Paper presented at 7th International Conference on Recrystallization and Grain Growth, Ghent,August 4-9, 2019. , 1270, Article ID 012023.
Open this publication in new window or tab >>A study of the static recrystallization behaviour of cast Alloy 825 after hot-compressions
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2019 (English)In: Journal of Physics: Conference Series, 2019, Vol. 1270, article id 012023Conference paper, Published paper (Refereed)
Abstract [en]

The static recrystallization behaviour of a columnar and equiaxed Alloy 825 material was studied on a Gleeble-3800 thermo-simulator by single-hit compression experiments. Deformation temperatures of 1000-1200 °C, a strain of up to 0.8, a strain rate of 1s-1, and relaxation times of 30, 180, and 300 s were selected as the deformation conditions to investigate the effects of the deformation parameters on the SRX behaviour. Furthermore, the influences of the initial grain structures on the SRX behaviors were studied. The microstructural evolution was studied using optical microscopy and EBSD. The EBSD measurements showed a relaxation time of 95 % for fractional recrystallization grains, 𝑡95, in both structures, was less than 30 seconds at the deformation temperatures 1100 °C and 1200 °C. However, fewer than 95% of recrystallized grains recrystallized when the deformation temperature was lowered to 1000 °C. From the grain-boundary misorientation distribution in statically recrystallized samples, the fraction of high-angle grain boundaries decreased with an increasing deformation temperature from 1000 °C to 1200 °C for a given relaxation time. This was attributed to grain coarsening

Series
Journal of Physics: Conference Series, ISSN 1742-6588
Keywords
Alloy 825, Static recrystallization, hot compression, Gleeble-3800 thermo simulator
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-258210 (URN)10.1088/1742-6596/1270/1/012023 (DOI)2-s2.0-85072107757 (Scopus ID)
Conference
7th International Conference on Recrystallization and Grain Growth, Ghent,August 4-9, 2019
Note

QC 20190916

Available from: 2019-09-10 Created: 2019-09-10 Last updated: 2022-09-08Bibliographically approved
Safara Nosar, N., Sandberg, F. & Engberg, G. (2018). Characterization of Hot Deformation Behavior in a 13% Chromium Steel. In: Proceedings of the THERMEC 2018: . Paper presented at THERMEC 2018: 10th International Conference on Processing and Manufacturing of Advanced Materials, July 8-13, 2018, Paris - FRANCE.
Open this publication in new window or tab >>Characterization of Hot Deformation Behavior in a 13% Chromium Steel
2018 (English)In: Proceedings of the THERMEC 2018, 2018Conference paper, Published paper (Refereed)
Abstract [en]

The behavior of a 13% chromium steel subjected to hot deformation has been studied by performing hot compression tests in the temperature range of 850 to 12000C and at strain rates from 0.01 to 10 s-1. The uniaxial hot compression tests were performed on a Gleeble thermo-mechanical simulator. The best function that fits the peak stress for the material and its relation to the Zener-Hollomon parameter (Z) is derived. The average activation energy of this alloy in the entire test domain was found to be about 557 [kJmol-1] and the dynamic recrystallization (DRX) kinetics was studied to find the fraction DRX during deformation.

National Category
Materials Engineering Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-285961 (URN)10.4028/www.scientific.net/MSF.941.458 (DOI)000468152500075 ()2-s2.0-85064075652 (Scopus ID)
Conference
THERMEC 2018: 10th International Conference on Processing and Manufacturing of Advanced Materials, July 8-13, 2018, Paris - FRANCE
Note

QC 20211221

Available from: 2020-11-16 Created: 2020-11-16 Last updated: 2024-01-18Bibliographically approved
Sandberg, F. (2014). Dead or alive: How municipalities can useservice design tools to create live servicesthat are flexible, mindful and involving. In: ServDes.2014 Service Future; Proceedings of the fourth Service Design and Service Innovation Conference; Lancaster University; United Kingdom; 9-11 April 2014: . Paper presented at ServDes.2014 Service Future; The fourth Service Design and Service Innovation Conference; Lancaster University; United Kingdom; 9-11 April 2014 (pp. 434-439). Linköping
Open this publication in new window or tab >>Dead or alive: How municipalities can useservice design tools to create live servicesthat are flexible, mindful and involving
2014 (English)In: ServDes.2014 Service Future; Proceedings of the fourth Service Design and Service Innovation Conference; Lancaster University; United Kingdom; 9-11 April 2014, Linköping, 2014, p. 434-439Conference paper, Published paper (Refereed)
Abstract [en]

Regional service innovation is an emerging and important topic within the European Union. According to the OECD it is becoming ever more crucial for each European municipality to support collaborations between regional stakeholders in order to be innovative and competitive. But collaborations between large municipalities with fixed service routines and small flexible SMEs are challenging. In this paper we argue that service design and service designers’ knowledge about different techniques can act as a new approach for municipalities to interact with SMEs in a creative way. As an example of this; the paper describes experiences from a workshop where service designers; SMEs and Swedish municipalities prototypes a visual mapping activity. From this first pilot study we learned that visual mapping is an activity that makes it possible for municipalities to step out of their standardised service routines and step into a more involving and flexible service offering.

Place, publisher, year, edition, pages
Linköping: , 2014
Keywords
participatory activity mapping, design tools, service routines
National Category
Design
Identifiers
urn:nbn:se:kth:diva-244602 (URN)
Conference
ServDes.2014 Service Future; The fourth Service Design and Service Innovation Conference; Lancaster University; United Kingdom; 9-11 April 2014
Note

QC 20190227

Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2022-06-26Bibliographically approved
Sandberg, F., Westerlund, B., Widmark, E. & Andersson, S. (2013). The struggles of co-creation – The highs and lows of involving stakeholders into the service design process. In: Luis M. Camarinha-Matos ; Raimar J. Scherer (Ed.), Collaborative Systems for Reindustrialization. 14th IFIP WG 5.5 Working Conference on Virtual Enterprises, PRO-VE 2013 Dresden, Germany, September/October 2013 Proceedings: . Paper presented at 14th IFIP WG 5.5 Working Conference on Virtual Enterprises, PRO-VE 2013, Dresden. (pp. 415-422). Heidelberg: Springer
Open this publication in new window or tab >>The struggles of co-creation – The highs and lows of involving stakeholders into the service design process
2013 (English)In: Collaborative Systems for Reindustrialization. 14th IFIP WG 5.5 Working Conference on Virtual Enterprises, PRO-VE 2013 Dresden, Germany, September/October 2013 Proceedings / [ed] Luis M. Camarinha-Matos ; Raimar J. Scherer, Heidelberg: Springer, 2013, p. 415-422Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents our experiences from a research project on how to co-develop new methods for idea generation within a service design practice. As an example the paper describes how service designers used two visual inquiry methods together with customers and employees in different service situations. The results show that that there is great potential in developing methods for co-design work based on design approaches. This project relies on a mindset where materials of different kinds, that can be organized and reorganized in different ways are used. This supports a way of creating knowledge that facilitates production of other results than the purely verbal. We have also realized that it requires a great amount of work to achieve a great result.

Place, publisher, year, edition, pages
Heidelberg: Springer, 2013
Keywords
Business Development, Co-creation, Co-Design, Idea Generation, Visual Methods, Service Design
National Category
Design
Identifiers
urn:nbn:se:kth:diva-244605 (URN)10.1007/978-3-642-40543-3_44 (DOI)2-s2.0-84897767324 (Scopus ID)978-3-642-40542-6 (ISBN)978-3-642-40543-3 (ISBN)
Conference
14th IFIP WG 5.5 Working Conference on Virtual Enterprises, PRO-VE 2013, Dresden.
Note

QC 20190227

Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2022-06-26Bibliographically approved
Sandberg, F. (2012). Co-creating collaborative food serviceopportunities through work context maps. In: Päivi J. Tossavainen ; Milla Harjula ; Stefan Holmlid (Ed.), ServDes. 2012 3rd Nordic Conference on Service Design and Service Innovation: CO-CREATING SERVICES. Paper presented at The 3rd Service Design and Service Innovation Conference, ServDes.2012, CO-CREATING SERVICES (pp. 243-251). Linköping
Open this publication in new window or tab >>Co-creating collaborative food serviceopportunities through work context maps
2012 (English)In: ServDes. 2012 3rd Nordic Conference on Service Design and Service Innovation: CO-CREATING SERVICES / [ed] Päivi J. Tossavainen ; Milla Harjula ; Stefan Holmlid, Linköping, 2012, p. 243-251Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a co-design workshop method where the participants use context maps of work activities as tools to visually explore collaborative service opportunities inside a food producer community. As an example the paper describes experiences from using the method together with small local food producers. During the workshop the food producers created and transferred knowledge regarding their work from the individual work maps to co-created future service maps. Although the food producers never had worked in these settings before,they had no problem sharing and co-creating complex work scenarios. The method uses both visual and verbal tools, which enables the participants to create a detailed service story as well as a visual overview. The use of the method encouraged the food producers to create service ideas, but it also started a dialog on how to bring the service concepts out to the real work context. The paper also reflects upon the method’s potential in supporting service designers.

Place, publisher, year, edition, pages
Linköping: , 2012
Series
Linköping Electronic Conference Proceedings, ISSN 1650-3686, E-ISSN 1650-3740 ; 67
Keywords
work context maps, creative communities, design method, visual tools
National Category
Design
Identifiers
urn:nbn:se:kth:diva-244601 (URN)978-91-7519-482-0 (ISBN)
Conference
The 3rd Service Design and Service Innovation Conference, ServDes.2012, CO-CREATING SERVICES
Note

QC 20190227

Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2022-06-26Bibliographically approved
Sandberg, F. (2011). VISUAL INQUIRY: A TOOL FOR PRESENTING AND SHARING CONTEXTUAL KNOWLEDGE. In: Nordic Design Research Conference 2011, Making Design Matter: . Paper presented at Nordic Design Research Conference 2011, Making Design Matter, Helsinki, Finland May 29, 2011 – May 31, 2011.
Open this publication in new window or tab >>VISUAL INQUIRY: A TOOL FOR PRESENTING AND SHARING CONTEXTUAL KNOWLEDGE
2011 (English)In: Nordic Design Research Conference 2011, Making Design Matter, 2011Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents an inquiry method where the participants create a visual presentation of their experiential knowledge of working. As an example the paper describes experiences from using the inquiry method together with small local food producers. The owners use the visual inquiry tool to present their small company's activities, the stakeholders involved, problems, strengths,changes and dreams for the future. Although the food producers never had described their knowledge as one picture before, they had no problem mapping out and visually presenting complex information about their production. The method uses sticky notes as mapping tools, which enables the participants to rearrange information,point at related information, jump in time and also include the research group in the knowledge creation. The use of the visual inquiry method increases the participants’ involvement and community building. The paper also describes how the visual presentations, created at several inquiry sessions, are used in a workshop on collaborative services.

National Category
Design
Identifiers
urn:nbn:se:kth:diva-244603 (URN)
Conference
Nordic Design Research Conference 2011, Making Design Matter, Helsinki, Finland May 29, 2011 – May 31, 2011
Note

QC 20190227

Available from: 2019-02-22 Created: 2019-02-22 Last updated: 2022-06-26Bibliographically approved
Al-Saadi, M., Hulme-Smith, C., Sandberg, F. & Jönsson, P.Hot Deformation Behaviour and Processing Map of Cast Alloy 825.
Open this publication in new window or tab >>Hot Deformation Behaviour and Processing Map of Cast Alloy 825
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Alloy 825 is a nickel-based alloy that is commonly used in applications where both high strength and corrosion resistance are required. Applications include tanks in the chemical, food and petrochemical industries and oil and gas pipelines. Components made from Alloy 825 are often manufactured using hot deformation. However, there is no systematic study to optimise the processing conditions reported in literature. In this study, a processing map for as-cast Alloy 825 is established to maximise the power dissipation efficiency of hot deformation and correlate the processing conditions to final materials properties. The hot deformation behaviour of equiaxed Alloy 825 is characterized on the basis of the dynamic materials model and compression data in the temperature range of 950 °C to 1250 °C at an interval of 50°C and strain rate range of 0.01 s-1 to 10 s-1 to a true strain of 0.7 using a Gleeble-3500 thermomechanical simulator. Flow stress is modelled by the constitutive equation based on a hyperbolic sine function. The deformed material is characterized using Vickers hardness, optical microscopy and scanning electron microscopy, including electron backscattered diffraction. The true stress-true strain curves exhibit peak stresses followed by softening due to occurrence of dynamic recrystallization. The value of stress exponent in the hyperbolic sine-based constitutive equation, n=5.0. This suggests that the rate-limiting mechanism of deformation is climb (diffusion)-mediated dislocation glide. The activation energy for plastic flow in the temperature range tested is about 450 kJ mole-1, and the relationship between flow stress and temperature-compensated strain rate (via the Zener-Hollomon parameter) was found to be valid across this temperature range. The maximum power dissipation efficiency is over 35%. The highest efficiency is observed over temperature range of 1100 °C – 1250 °C and a strain rate of 0.01 s-1 – 0.1s-1. These are the optimum conditions for hot working. The optimum processing parameters for good strain hardening are obtained in the temperature range of between  950 °C  and  1100 °C with a strain rate between  0.3/s  and 10.0/s. 

Keywords
Alloy 825, Hot-deformation; Stress-strain curve; Activation energy; Dynamically recrystallized; grain size
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-295474 (URN)
Note

QC 20210525

Available from: 2021-05-21 Created: 2021-05-21 Last updated: 2022-06-25Bibliographically approved
Al-Saadi, M., Sandberg, F., Jönsson, P. & Hulme-Smith, C.Influence of Strain Magnitude on Microstructure, Texture and Mechanical Properties of Alloy 825 during hot-forging.
Open this publication in new window or tab >>Influence of Strain Magnitude on Microstructure, Texture and Mechanical Properties of Alloy 825 during hot-forging
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Alloy 825 is a nickel-base alloy that is common in applications with high stresses and corrosive environments. It is commonly processed by hot forging, but there are few data about how hot forging affects the microstructure, which is critical for both mechanical and corrosion performance. Here, the alloy was hot forged in a commercial thermomechanical process to three industrially-relevant strains and the microscture was examined using scanning electron microscopy and EBSD. The tensile properties were also measured after thermomechanical treatment. Dynamic recrystallization was prevalent during the process, so increasing the forging strain leads to smaller grains and also higher dislocation density. Data were combined to allow the 0.2% proof stress to be calculated as a function of forging strain. All forging strains were sufficient to meet the criteria of the relevant industrial standard for this material. The maximum yield strength and ultimate tensile strength were obtained after forging to a true strain of 0.9 were 413 MPa and 622 MPa, respecitvely, with a ductlity of 40%. This may be used to tailor thermomechanical treatments to achieve precise mechanical properties and serve as a basis for future studies into the corrosion performance of this alloy as a function of forging strain.

Keywords
Alloy 825, Hot forging, Grain structure, Yield strength, Strengthening mechanisms
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-295473 (URN)
Note

QC 20210525

Available from: 2021-05-21 Created: 2021-05-21 Last updated: 2022-06-25Bibliographically approved
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