Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa

Pekka Nevasmaa, Päivi Karjalainen-Roikonen, Anssi Laukkanen, T. Nykänen, A. Ameri, T. Björk, T. Limnell, J. Kuoppala

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

    Abstract

    The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 % decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.
    Original languageEnglish
    Title of host publicationProceedings
    Subtitle of host publication2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010
    Place of PublicationMilano
    PublisherAssociazione Italiana di Metallurgia AIM
    Number of pages14
    ISBN (Print)978-88-85298-79-8
    Publication statusPublished - 2010
    MoE publication typeB3 Non-refereed article in conference proceedings

    Fingerprint

    High strength steel
    Yield stress
    Brittle fracture
    Fracture mechanics
    Loads (forces)
    Aging of materials
    Temperature
    Bending tests
    Testing
    Bearing capacity
    Fracture toughness
    Fatigue of materials
    Finite element method
    Steel

    Cite this

    Nevasmaa, P., Karjalainen-Roikonen, P., Laukkanen, A., Nykänen, T., Ameri, A., Björk, T., ... Kuoppala, J. (2010). Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. In Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010 Milano: Associazione Italiana di Metallurgia AIM.
    Nevasmaa, Pekka ; Karjalainen-Roikonen, Päivi ; Laukkanen, Anssi ; Nykänen, T. ; Ameri, A. ; Björk, T. ; Limnell, T. ; Kuoppala, J. / Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Milano : Associazione Italiana di Metallurgia AIM, 2010.
    @inproceedings{979675266d57459287739ed3943f9170,
    title = "Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa",
    abstract = "The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 {\%} decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.",
    author = "Pekka Nevasmaa and P{\"a}ivi Karjalainen-Roikonen and Anssi Laukkanen and T. Nyk{\"a}nen and A. Ameri and T. Bj{\"o}rk and T. Limnell and J. Kuoppala",
    year = "2010",
    language = "English",
    isbn = "978-88-85298-79-8",
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    publisher = "Associazione Italiana di Metallurgia AIM",
    address = "Italy",

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    Nevasmaa, P, Karjalainen-Roikonen, P, Laukkanen, A, Nykänen, T, Ameri, A, Björk, T, Limnell, T & Kuoppala, J 2010, Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. in Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Associazione Italiana di Metallurgia AIM, Milano.

    Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. / Nevasmaa, Pekka; Karjalainen-Roikonen, Päivi; Laukkanen, Anssi; Nykänen, T.; Ameri, A.; Björk, T.; Limnell, T.; Kuoppala, J.

    Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Milano : Associazione Italiana di Metallurgia AIM, 2010.

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

    TY - GEN

    T1 - Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa

    AU - Nevasmaa, Pekka

    AU - Karjalainen-Roikonen, Päivi

    AU - Laukkanen, Anssi

    AU - Nykänen, T.

    AU - Ameri, A.

    AU - Björk, T.

    AU - Limnell, T.

    AU - Kuoppala, J.

    PY - 2010

    Y1 - 2010

    N2 - The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 % decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.

    AB - The fracture behaviour of S960 steel in different conditions, i.e as-delivered, cold strained, cold strained and artificially aged, has been studied using small-scale fracture mechanics and Charpy V testing as well as tests on large-scale U-beams and cold-formed rectangular hollow sections. At room temperature and -40 deg C, fracture resistance testing indicated overall ductile behaviour. Regarding brittle fracture, the T0 reference temperature for the as-received material was around -50 deg C. Artificial ageing alone increased this temperature only slightly, but cold-straining and artificial ageing together raised T0 (and T28J) by almost 50 deg C. For the strength level studied, the FITNET correlation between T0 and T28J leads to severely un-conservative KJC estimates, indicating that KJC needs to be measured directly. T0 estimates based on fracture mechanics tests using small-scale 3-point bend specimens were clearly conservative in relation to the large-scale U-beam behaviour due to different constraints. Shear fracture occurred in the U-beam tests as a result of the small plate thickness; however, this led to only a 10 % decrease in the load-bearing capacity from the theoretical maximum load. Quasi-static bending tests on welded fatigue-cracked cold-formed rectangular hollow sections at -40 deg C showed good agreement with nonlinear FEA calculations using the J-integral approach. Both large-scale test variants showed that brittle cleavage fracture will not become the dominant fracture mode in the welded beam constructions studied, provided the service temperature does not fall below -50 deg C.

    M3 - Conference article in proceedings

    SN - 978-88-85298-79-8

    BT - Proceedings

    PB - Associazione Italiana di Metallurgia AIM

    CY - Milano

    ER -

    Nevasmaa P, Karjalainen-Roikonen P, Laukkanen A, Nykänen T, Ameri A, Björk T et al. Fracture characteristics of new ultra-high-strength steel with yield strengths 900-960 MPa. In Proceedings: 2nd International Conference Super-High Strength Steels (SHSS), Peschiera del Garda, 17-20 October 2010. Milano: Associazione Italiana di Metallurgia AIM. 2010