Weldability of direct-quenched and tempered (DQT) high strength steel HT80

Pekka Nevasmaa, Mark Cederberg, Martti Vilpas

    Research output: Book/ReportReport

    Abstract

    The report gives and briefly discusses the test results obtained in welding and weldability tests of a direct-quenched and tempered steel DQT HT80. The tests comprised of mechanical testing of joints welded with arc energies of 20 and 45 kJ/cm using SAW and FCAW processes. Also the results of weld thermal simulation and Implant weldability tests for the steel are reported and discussed. The results demonstrate the improved weldability of the DQT HT80 steel, as compared to conventional QT steels of similar strength level. The need for preheat was found 70-90°C lower for the DQT steel. Cracking of weld metal instead of HAZ, however, suggested that increasing preheat and interpass temperatures even up to 150°C become necessary with heavier plate thicknesses of 40 mm and above. With both arc energies (20, 45 kJ/cm), SAW yielded higher weld metal toughness than FCAW. In SA-welds, impact energy constantly and considerably exceeded the required level of 40 J at -40°C. This was not the case with FCA weld metals, as in the majority of welds the impact energy level of 40 J at -40°C was hardly met. The HAZ toughness properties of DQT HT80 steel were found to deteriorate as the arc energy increased from 20 to 45 kJ/cm. The Charpy-V impact energy requirement of 40 J was fulfilled at -40°C in all weldments with an arc energy of 20 kJ/cm, whilst none of the weldments qualified with an arc energy of 45 kJ/cm. The Charpy-V tests of simulated HAZ confirmed the tendency of decreasing HAZ toughness with prolonged cooling times. Whilst adequate impact toughness values were obtained with t8/5 < 24 sec, a deterioration in toughness was evident with t8/5 > 30 sec.
    Original languageEnglish
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Number of pages41
    ISBN (Print)951-38-4300-9
    Publication statusPublished - 1992
    MoE publication typeNot Eligible

    Publication series

    SeriesVTT Tiedotteita - Meddelanden - Research Notes
    Number1406
    ISSN1235-0605

    Fingerprint

    Weldability
    High strength steel
    Welds
    Toughness
    Steel
    Flux-cored arc welding (FCAW)
    Metals
    Mechanical testing
    Heat affected zone
    Electron energy levels
    Deterioration
    Fracture toughness
    Welding
    Cooling

    Keywords

    • high strength steels
    • welded joints
    • weldability
    • mechanical properties
    • arc welding
    • tests
    • simulation
    • strength
    • toughness
    • fracture properties
    • DQT
    • HT80

    Cite this

    Nevasmaa, P., Cederberg, M., & Vilpas, M. (1992). Weldability of direct-quenched and tempered (DQT) high strength steel HT80. Espoo: VTT Technical Research Centre of Finland. VTT Tiedotteita - Meddelanden - Research Notes, No. 1406
    Nevasmaa, Pekka ; Cederberg, Mark ; Vilpas, Martti. / Weldability of direct-quenched and tempered (DQT) high strength steel HT80. Espoo : VTT Technical Research Centre of Finland, 1992. 41 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 1406).
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    Nevasmaa, P, Cederberg, M & Vilpas, M 1992, Weldability of direct-quenched and tempered (DQT) high strength steel HT80. VTT Tiedotteita - Meddelanden - Research Notes, no. 1406, VTT Technical Research Centre of Finland, Espoo.

    Weldability of direct-quenched and tempered (DQT) high strength steel HT80. / Nevasmaa, Pekka; Cederberg, Mark; Vilpas, Martti.

    Espoo : VTT Technical Research Centre of Finland, 1992. 41 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 1406).

    Research output: Book/ReportReport

    TY - BOOK

    T1 - Weldability of direct-quenched and tempered (DQT) high strength steel HT80

    AU - Nevasmaa, Pekka

    AU - Cederberg, Mark

    AU - Vilpas, Martti

    PY - 1992

    Y1 - 1992

    N2 - The report gives and briefly discusses the test results obtained in welding and weldability tests of a direct-quenched and tempered steel DQT HT80. The tests comprised of mechanical testing of joints welded with arc energies of 20 and 45 kJ/cm using SAW and FCAW processes. Also the results of weld thermal simulation and Implant weldability tests for the steel are reported and discussed. The results demonstrate the improved weldability of the DQT HT80 steel, as compared to conventional QT steels of similar strength level. The need for preheat was found 70-90°C lower for the DQT steel. Cracking of weld metal instead of HAZ, however, suggested that increasing preheat and interpass temperatures even up to 150°C become necessary with heavier plate thicknesses of 40 mm and above. With both arc energies (20, 45 kJ/cm), SAW yielded higher weld metal toughness than FCAW. In SA-welds, impact energy constantly and considerably exceeded the required level of 40 J at -40°C. This was not the case with FCA weld metals, as in the majority of welds the impact energy level of 40 J at -40°C was hardly met. The HAZ toughness properties of DQT HT80 steel were found to deteriorate as the arc energy increased from 20 to 45 kJ/cm. The Charpy-V impact energy requirement of 40 J was fulfilled at -40°C in all weldments with an arc energy of 20 kJ/cm, whilst none of the weldments qualified with an arc energy of 45 kJ/cm. The Charpy-V tests of simulated HAZ confirmed the tendency of decreasing HAZ toughness with prolonged cooling times. Whilst adequate impact toughness values were obtained with t8/5 < 24 sec, a deterioration in toughness was evident with t8/5 > 30 sec.

    AB - The report gives and briefly discusses the test results obtained in welding and weldability tests of a direct-quenched and tempered steel DQT HT80. The tests comprised of mechanical testing of joints welded with arc energies of 20 and 45 kJ/cm using SAW and FCAW processes. Also the results of weld thermal simulation and Implant weldability tests for the steel are reported and discussed. The results demonstrate the improved weldability of the DQT HT80 steel, as compared to conventional QT steels of similar strength level. The need for preheat was found 70-90°C lower for the DQT steel. Cracking of weld metal instead of HAZ, however, suggested that increasing preheat and interpass temperatures even up to 150°C become necessary with heavier plate thicknesses of 40 mm and above. With both arc energies (20, 45 kJ/cm), SAW yielded higher weld metal toughness than FCAW. In SA-welds, impact energy constantly and considerably exceeded the required level of 40 J at -40°C. This was not the case with FCA weld metals, as in the majority of welds the impact energy level of 40 J at -40°C was hardly met. The HAZ toughness properties of DQT HT80 steel were found to deteriorate as the arc energy increased from 20 to 45 kJ/cm. The Charpy-V impact energy requirement of 40 J was fulfilled at -40°C in all weldments with an arc energy of 20 kJ/cm, whilst none of the weldments qualified with an arc energy of 45 kJ/cm. The Charpy-V tests of simulated HAZ confirmed the tendency of decreasing HAZ toughness with prolonged cooling times. Whilst adequate impact toughness values were obtained with t8/5 < 24 sec, a deterioration in toughness was evident with t8/5 > 30 sec.

    KW - high strength steels

    KW - welded joints

    KW - weldability

    KW - mechanical properties

    KW - arc welding

    KW - tests

    KW - simulation

    KW - strength

    KW - toughness

    KW - fracture properties

    KW - DQT

    KW - HT80

    M3 - Report

    SN - 951-38-4300-9

    T3 - VTT Tiedotteita - Meddelanden - Research Notes

    BT - Weldability of direct-quenched and tempered (DQT) high strength steel HT80

    PB - VTT Technical Research Centre of Finland

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    ER -

    Nevasmaa P, Cederberg M, Vilpas M. Weldability of direct-quenched and tempered (DQT) high strength steel HT80. Espoo: VTT Technical Research Centre of Finland, 1992. 41 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 1406).