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

CY - Espoo

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).