Ulla Ehrnstén

Principle Scientist

  • Phone+358405354057
1989 …2020

Research output per year

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Research Output

2020

Effect of thermal ageing at 400 °C on the microstructure of ferrite-austenite interface of nickel-base alloy narrow-gap dissimilar metal weld

Ahonen, M., Mouginot, R., Sarikka, T., Lindqvist, S., Que, Z., Ehrnstén, U., Virkkunen, I. & Hänninen, H., Mar 2020, In : Metals. 10, 3, 421.

Research output: Contribution to journalArticleScientificpeer-review

Open Access

Stress corrosion crack initiation testing with tapered specimens in high-temperature water–results of a collaborative research project

Bosch, R. W., Ritter, S., Herbst, M., Kilian, R., Burke, M. G., Duff, J., Scenini, F., Gu, Y., Dinu, A., Ehrnstén, U., Toivonen, A., Novotny, R., Martin, O., Perosanz, F. J., Legat, A. & Zajec, B., 8 Sep 2020, In : Corrosion Engineering Science and Technology. 16 p.

Research output: Contribution to journalArticleScientificpeer-review

Open Access
2019

Determination of T0 with Miniature C(T) Specimens for a High-Ni Weld Metal used in a Boiling Water Reactor Pressure Vessel

Sirkiä, L., Lydman, J., Ehrnstén, U. & Lindqvist, S., 2019, Baltica XI: International Conference on Life Management and Maintenance for Power Plants. VTT Technical Research Centre of Finland, 10 p.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Open Access
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Effect of thermal aging on microstructure and hardness of industrial heats of Alloy 690

Huotilainen, C., Ehrnstén, U., Ahonen, M. & Hänninen, H., 2019, 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors. American Nuclear Society ANS, p. 156-164 9 p.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Electrochemical investigation of in-service thermal aging in two CF8M cast stainless steels

Huotilainen, C., Ivanchenko, M., Efsing, P. & Ehrnsten, U., Jul 2019, In : Journal of Nuclear Materials. 520, p. 34-40 7 p.

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Microstructural characterization of thermally aged Barsebäck RPV head weld metal

Lydman, J., Hytönen, N., Que, Z., Ehrnstén, U. & Nevasmaa, P., 11 Aug 2019, VTT Technical Research Centre of Finland. 36 p. (VTT Research Report; No. VTT-R-01003-19).

Research output: Book/ReportReport

Nanoindentation study of short-range ordering

Mouginot, R., Sarikka, T., Ehrnstén, U. & Hänninen, H., 25 Jan 2019, In : Materials Research Express. 6, 4, 8 p., 045052.

Research output: Contribution to journalArticleScientificpeer-review

Open Access
1 Citation (Scopus)
2018

Development of short-range order and intergranular carbide precipitation in Alloy 690 TT upon thermal ageing

Mouginot, R., Sarikka, T., Heikkilä, M., Ivanchenko, M., Tapper, U., Ehrnstén, U. & Hänninen, H., 1 Jan 2018, Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. Paraventi, D., Wright, M. & Jackson, J. H. (eds.). Springer, p. 321-334 14 p. (Minerals, Metals and Materials Series, Vol. Part F9).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

1 Citation (Scopus)

Effect of thermal aging on fracture mechanical and microstructural properties of Alloy 52 narrow-gap safe-end dissimilar metal weld

Ahonen, M., Sarikka, T., Mouginot, R., Lindqvist, S., Lydman, J., Ehrnsten, U., Nevasmaa, P. & Hänninen, H., 2018, Proceedings of “Fontevraud 9 - Contribution of Materials Investigation and Operating Experience to Light Water NPPs Safety, Performance and Reliability”, Avignon, 17-20 September 2018. France, 2018.. 13 p.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

Effect of thermal aging on fracture mechanical properties and crack propagation behavior of alloy 52 narrow-gap dissimilar metal weld

Ahonen, M., Lindqvist, S., Sarikka, T., Lydman, J., Mouginot, R., Ehrnstén, U., Nevasmaa, P. & Hänninen, H., 1 Jan 2018, Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. Jackson, J. H., Paraventi, D. & Wright, M. (eds.). Springer, Vol. 2. p. 733-747 15 p. (Minerals, Metals and Materials Series; No. Part F11).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Microbially induced corrosion in fire fighting systems - experience and remedies

Ehrnstén, U., Carpén, L. & Tompuri, K., 2018, Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors . Wright, M., Paraventi, D. & Jackson, J. H. (eds.). Springer, p. 831-840 10 p. (Minerals, Metals and Materials Series, Vol. Part F11).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Microstructural characterization of alloy 52 narrow-gap dissimilar metal weld after aging

Sarikka, T., Mouginot, R., Ahonen, M., Lindqvist, S., Ehrnstén, U., Nevasmaa, P. & Hänninen, H., 1 Jan 2018, Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. Jackson, J. H., Paraventi, D. & Wright, M. (eds.). Springer, Vol. 2. p. 763-777 15 p. (Minerals, Metals and Materials Series; No. Part F11).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

1 Citation (Scopus)

Microstructural investigations of the 300-series austenitic stainless steels irradiated to different fluences after in-pile mechanical test

Ivanchenko, M., Ehrnsten, U. & Karlsen, T., 2018, Proceedings of Fontevraud 9: Contribution of Materials Investigation and Operating Experience to Light Water NPPs Safety, Performance and Reliability. 9 p.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Thermal ageing and mechanical performance of narrow-gap dissimilar metal welds

Ahonen, M., Lindqvist, S., Leskelä, E., Lydman, J., Nevasmaa, P., Seppänen, T., Arffman, P., Ehrnsten, U., Sarikka, T., Mouginot, R. & Hänninen, H., Jun 2018, Espoo: VTT Technical Research Centre of Finland. 189 p. (VTT Technology; No. 333).

Research output: Book/ReportReport

Open Access
2017

Effect of mechanical mismatch on fracture mechanical behavior of SA 508 - Alloy 52 narrow gap dissimilar metal weld

Sarikka, T., Ahonen, M., Mouginot, R., Nevasmaa, P., Karjalainen-Roikonen, P., Ehrnstén, U. & Hänninen, H., 1 Nov 2017, In : International Journal of Pressure Vessels and Piping. 157, p. 30-42 13 p.

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)

Intergranular stress corrosion cracking of austenitic stainless steels: Is it still an issue?

Ehrnstén, U., 1 Jan 2017, European Corrosion Congress (EUROCORR 2017) and 20th International Corrosion Congress and Process Safety Congress 2017: Corrosion Control for Safer Living. 22 p.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

On flux effects in a low alloy steel from a Swedish reactor pressure vessel

Boåsen, M., Efsing, P. & Ehrnstén, U., 2017, In : Journal of Nuclear Materials. 484, p. 110-119 10 p.

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)

Thermal ageing and EAC research for plant life management (THELMA)

Ehrnstén, U., Ahonen, M., Autio, J-M., Ivanchenko, M., Hurley, C., Toivonen, A., Mouginot, R., Ilola, R. & Hänninen, H., 2017, SAFIR2018 - The Finnish Research Programme on Nuclear Power Plant Safety 2015-2018: Interim Report. VTT Technical Research Centre of Finland, p. 319-330 (VTT Technology, Vol. 294).

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

Open Access

Thermal ageing and short-range ordering of Alloy 690 between 350 and 550 °C

Mouginot, R., Sarikka, T., Heikkilä, M., Ivanchenko, M., Ehrnstén, U., Kim, Y. S., Kimsung, S. & Hänninen, H., 1 Mar 2017, In : Journal of Nuclear Materials. 485, p. 56-66 11 p.

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)
2016

Analytical examination of welds of surrogate and archive RPV materials

Ehrnstén, U., Autio, J-M., Ivanchenko, M., Nevasmaa, P. & Efsing, P., 2016. 20 p.

Research output: Contribution to conferenceConference articleScientific

Creep performance of fuel cladding

Pohja, R., Tulkki, V., Ikonen, T., Moilanen, P., Rantala, J., Huotilainen, S. & Ehrnstén, U., 2016, Baltica X: International Conference on Life Management and Maintenance for Power Plants. Auerkari, P. (ed.). Espoo: VTT Technical Research Centre of Finland, 8 p. (VTT Technology, Vol. 261).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Open Access

Fracture mechanical and microstructural characterization of narrow-gap safe-end dissimilar metal weld

Ahonen, M., Mouginot, R., Lindqvist, S., Sarikka, T., Nevasmaa, P., Ehrnstén, U. & Hänninen, H., 2016, Baltica X: International Conference on Life Management and Maintenance for Power Plants. Auerkari, P. (ed.). VTT Technical Research Centre of Finland, 16 p. (VTT Technology, Vol. 261).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Open Access

Location of initiation sites in fracture toughness testing specimens-the effect of size and side grooves

Wallin, K., Yamamoto, M. & Ehrnstén, U., 2016, ASME 2016 Pressure Vessels and Piping Conference: Codes and Standards. American Society of Mechanical Engineers ASME, Vol. 1B. 9 p. PVP2016-63078

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

2 Citations (Scopus)

Microstructural, mechanical, and fracture mechanical characterization of SA 508-Alloy 182 dissimilar metal weld in view of mismatch state

Sarikka, T., Ahonen, M., Mouginot, R., Nevasmaa, P., Karjalainen-Roikonen, P., Ehrnsten, U. & Hänninen, H., 2016, In : International Journal of Pressure Vessels and Piping. 145, p. 13-22

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)

Multiaxial creep testing device for nuclear fuel claddings

Pohja, R., Moilanen, P., Rantala, J., Huotilainen, S., Tulkki, V., Ehrnstén, U. & Holmström, S., 2016, In : Athens Journal of Sciences. 3, 3, p. 227-240

Research output: Contribution to journalArticleScientificpeer-review

Open Access

Short-range ordering of Alloy 690 aged for 10 000 h at 420, 475 and 550 °C

Mouginot, R., Sarikka, T., Ehrnstén, U., Kim, Y. S., Kim, S. S. & Hänninen, H., 2016, Baltica X: International Conference on Life Management and Maintenance for Power Plants. Auerkari, P. (ed.). Espoo: VTT Technical Research Centre of Finland, 8 p. (VTT Technology, Vol. 261).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Open Access

Thermal Aging Induced Phase Transformations in Nuclear Grade Typr 316L Stainless Steel Weld Metals

Ivanchenko, M., Ehrnstén, U., Forsström, A., Hänninen, H. & Ballinger, R. G., 2016.

Research output: Contribution to conferenceConference articleScientific

2015

Effect of heat treatment and cold work on the ordening of alloy 690 at 475 °C

Mouginot, R., Sarikka, Heikkilä, M., Ehrnstén, U., Kim, Y. S., Sung, S. K. & Hänninen, H., 2015, p. 17.

Research output: Contribution to conferenceConference articleScientific

Factors affecting low temperature crack propagation (LTCP)

Ahonen, M., Ehrnstén, U., Saukkonen, T., Todoshchenko, O. & Hänninen, H., 2015. 18 p.

Research output: Contribution to conferenceConference articleScientific

IGSCC in a BWR steam line after 30 years of operation

Ehrnstén, U., Autio, J-M. & Holmström, P., 2015. 10 p.

Research output: Contribution to conferenceConference articleScientific

Results from pre-tests on liquid metal embrittlement

Autio, J-M. & Ehrnsten, U., 2015, VTT Technical Research Centre of Finland. 26 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, Vol. VTT-R-00308-15).

Research output: Book/ReportReport

2014

DL-EPR measurements on a sensitised Type 304 stainless steel pipe section

Autio, J-M. & Ehrnsten, U., 2014, VTT Technical Research Centre of Finland. 19 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports; No. VTT-R-05905-14).

Research output: Book/ReportReport

Investigations of a Type 316L Steam Dryer Plate Material Suffering from IGSCC After a Few Years in BWR Conditions

Autio, J-M., Ehrnstén, U., Mouginot, R., Pakarinen, J. & Cocco, M., 2014, In : Microscopy and Microanalysis. 20, S3, p. 1870-1871

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Status report on project MICRIN, Mitigation of Crack Initiation

Ehrnsten, U., 2014, VTT Technical Research Centre of Finland. 7 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports; No. VTT-R-05439-14).

Research output: Book/ReportReport

Structural integrity of Ni-base alloy welds

Hänninen, H., Brederholm, A., Sarikka, T., Mouginot, R., Holmström, P., Saukkonen, T., Toivonen, A., Karjalainen-Roikonen, P., Nevasmaa, P., Keinänen, H., Leskelä, E., Ahonen, M., Ehrnsten, U. & Aaltonen, P., 2014, Espoo: VTT Technical Research Centre of Finland. 264 p. (VTT Technology, Vol. 175).

Research output: Book/ReportReport

Open Access

Super slow strain rate testing in simulated LWR conditions

Ehrnstén, U., 2014, VTT Technical Research Centre of Finland. 37 p. (VTT Research Report; No. VTT-R-06114-14).

Research output: Book/ReportReport

Supplementary tests with CRIEPI mini CT-specimens

Valo, M., Ehrnsten, U., Planman, T., Lappalainen, P. & Wallin, K., 2014, VTT Technical Research Centre of Finland. 71 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports; No. VTT-R-05628-14).

Research output: Book/ReportReport

The biaxial creep testing device, Crebello

Moilanen, P. & Ehrnstén, U., 2014, Espoo: VTT Technical Research Centre of Finland. 23 p. (VTT Research Report; No. VTT-R-01863-14).

Research output: Book/ReportReport

The effect of microstructure on Low-Temperature Crack Propagation (LTCP) susceptibility of nickel-based Alloy 182, 152 and 52 weld metals in PWR primary water

Ahonen, M., Ehrnstén, U., Saukkonen, T., Todoshchenko, O. & Hänninen, H., 2014, Proceedings of Fontevraud 8 . 15 p.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

2013

Ageing degradation of hard-facing alloy after long-time exposure BWR conditions II

Aaltonen, P., Karjalainen-Roikonen, P., Autio, J-M., Ehrnstén, U., Saukkonen, T. & Hänninen, H., 2013, VTT Technical Research Centre of Finland. 29 p. (VTT Research Report; No. VTT-R-06904-14).

Research output: Book/ReportReport

Environmental influence on cracking susceptibility and ageing of nuclear materials (ENVIS)

Ehrnsten, U., Pakarinen, J., Karlsen, W., Hänninen, H., Mouginot, R., Soinila, E., Ahonen, M., Autio, J-M., Aaltonen, P. & Saukkonen, T., 2013, SAFIR2014. The Finnish Research Programme on Nuclear Power Plant Safety 2011-2014. Espoo: VTT Technical Research Centre of Finland, p. 268-282 (VTT Technology; No. 201).

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

Fracture mechanical characterisation of ferrite-austenite dissimilar metal welds (DMWs) for elevated temperature service in view of metallurgical mis-match

Nevasmaa, P., Holmström, P., Karjalainen-Roikonen, P., Sarikka, T., Ahonen, M., Mouginot, R., Ehrnsten, U., Brederholm, A., Aaltonen, P. & Hänninen, H., 2013, Baltica IX. International Conference on Life Management and Maintenance for Power Plants. VTT Technology 106. Espoo: VTT Technical Research Centre of Finland, p. 152-173

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

Open Access

Fracture mechanical characterisation of ferrite-austenite dissimilar metal welds (DMWs) for elevated temperature service in view of metallurgical mis-match (Only the abstract)

Nevasmaa, P., Holmström, P., Karjalainen-Roikonen, P., Sarikka, T., Ahonen, M., Mouginot, R., Ehrnsten, U., Brederholm, A., Aaltonen, P. & Hänninen, H., 2013, Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. Espoo: VTT Technical Research Centre of Finland, p. 106-106

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

Open Access

Investigation of coatings, applied by PVD, for the corrosion protection of materials in supercritical water

Van Nieuwenhove, R., Balak, J., Toivonen, A., Penttilä, S. & Ehrnstén, U., 2013. 12 p.

Research output: Contribution to conferenceConference articleScientific

Investigations on core basket bolts from a VVER 440 power plant

Ehrnsten, U., Pakarinen, J., Karlsen, W. & Keinänen, H., 2013, In : Engineering Failure Analysis. 33, p. 55-65 11 p.

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)

Microstructural Characterization of Irradiated Baffle Bolts Removed from a Finnish VVER and a French PWR

Pakarinen, J., Ehrnstén, U., Keinänen, H. & Karlsen, W., 2013, Proceeding of the 16th International Conference on Environmental Degradation of Materials in Nuclear power Systems : Water Reactors. Vol. 1-3. p. 994-1007

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

2012

Corrosion and Stress Corrosion Cracking of Austenitic Stainless Steels

Ehrnstén, U., 2012, Comprehensive nuclear materials. Konings, R. J. M., Allen, T. R., Stoller, R. E. & Yamanaka, S. (eds.). Amsterdam: Elsevier, p. 93-104

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleScientificpeer-review

Open Access
14 Citations (Scopus)

Lifetime prediction techniques for nuclear power plant systems

Aho-Mantila, I., Cronvall, O., Ehrnstén, U., Keinänen, H., Rintamaa, R., Saarenheimo, A., Simola, K. & Vesikari, E., 2012, Nuclear Corrosion Science and Engineering. Féron, D. (ed.). Cambridge, UK: Woodhead Publishing, p. 449-470 (Woodhead publishing series in energy, Vol. Number 22).

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleScientificpeer-review

Open Access
1 Citation (Scopus)
2011

Deformation microstructures of 30 dpa AISI 304 stainless steel after monotonic tensile and constant load autoclave testing

Karlsen, W., Pakarinen, J., Toivonen, A. & Ehrnstén, U., 2011, 15th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors. Busby, J. T., Ilevbare, G. & Andresen, P. L. (eds.). Wiley, p. 1352-1366

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

7 Citations (Scopus)