Factors affecting low temperature crack propagation (LTCP)

Matias Ahonen, Ulla Ehrnstén, Tapio Saukkonen, Olga Todoshchenko, Hannu Hänninen

    Research output: Contribution to conferenceConference articleScientific

    Abstract

    The effect of hydrogenated PWR primary water on the Low Temperature Crack Propagation (LTCP) susceptibility of the nickel-based Alloy 182, 82, 152 and 52 weld metals was studied performing J-R tests for all-weld metal and dissimilar metal weld (DMW) mock-up specimens at a slow displacement rate in simulated low temperature PWR primary water. Single edge bend (SE(B)) specimens were tested in hydrogenated environments (100, 30 and 5 cm3 H2/kg H2O) with and without exposure to high-temperature hydrogenated PWR water prior to loading (24 h or 30 days at 300??C). Additionally, the effect of post-weld heat treatment on LTCP behaviour of Alloy 182 and 52 weld metals was studied. It was observed that Alloy 182 was the most susceptible material to LTCP, but also some specimens of Alloy 52 exhibited rather low JQ values, similar to those of Alloy 182, when tested with highest hydrogen content. Specimens of DMW Alloy 52 behaved in varying manner when tested with high hydrogen content, in both AW and PWHT conditions. PWHT seems to increase the tearing resistance of Alloy 182. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive Xray spectroscopy (EDS) were applied in order to examine the cracking path and to characterize the microstructural features affecting hydrogen trapping in Alloy 182 and 52 weld metals. A clear relation between high hydrogen content of the water, low fracture resistance values and intergranular/interdendritic type of fracture was observed, although also transgranular brittle-like fracture was observed in DMW Alloy 182 and all-weld metal Alloy 82 specimens tested in low temperature hydrogenated water. Hydrogen thermal desorption spectrometry (TDS) measurements were performed for Alloys 182 and 52 by using varying heating rates in order to study the effect of high temperature pre-exposure, different trapping sites and trapping activation energies. The high temperature pre-exposure was found to decrease the hydrogen content of Alloy 182 and 152 weld metals and consistently the fracture resistance values were increased. Different factors affecting the LTCP behaviour of nickel-based weld metals are discussed.
    Original languageEnglish
    Number of pages18
    Publication statusPublished - 2015
    Event17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015 - Ottawa, Canada
    Duration: 9 Aug 201512 Aug 2015

    Conference

    Conference17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015
    Abbreviated titleENVDEG 2015
    CountryCanada
    CityOttawa
    Period9/08/1512/08/15

    Fingerprint

    Crack propagation
    Welds
    Dissimilar metals
    Hydrogen
    Temperature
    Metals
    Water
    Fracture toughness
    Nickel
    Thermal desorption
    Heating rate
    Spectrometry
    Activation energy
    Heat treatment
    Spectroscopy
    Transmission electron microscopy
    Scanning electron microscopy

    Keywords

    • nickel-based weld metal alloys
    • low temperature crack propagation
    • hydrogen trapping
    • fracture resistance

    Cite this

    Ahonen, M., Ehrnstén, U., Saukkonen, T., Todoshchenko, O., & Hänninen, H. (2015). Factors affecting low temperature crack propagation (LTCP). Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.
    Ahonen, Matias ; Ehrnstén, Ulla ; Saukkonen, Tapio ; Todoshchenko, Olga ; Hänninen, Hannu. / Factors affecting low temperature crack propagation (LTCP). Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.18 p.
    @conference{ef60ee2f406a40dc935e6bb23a2099ce,
    title = "Factors affecting low temperature crack propagation (LTCP)",
    abstract = "The effect of hydrogenated PWR primary water on the Low Temperature Crack Propagation (LTCP) susceptibility of the nickel-based Alloy 182, 82, 152 and 52 weld metals was studied performing J-R tests for all-weld metal and dissimilar metal weld (DMW) mock-up specimens at a slow displacement rate in simulated low temperature PWR primary water. Single edge bend (SE(B)) specimens were tested in hydrogenated environments (100, 30 and 5 cm3 H2/kg H2O) with and without exposure to high-temperature hydrogenated PWR water prior to loading (24 h or 30 days at 300??C). Additionally, the effect of post-weld heat treatment on LTCP behaviour of Alloy 182 and 52 weld metals was studied. It was observed that Alloy 182 was the most susceptible material to LTCP, but also some specimens of Alloy 52 exhibited rather low JQ values, similar to those of Alloy 182, when tested with highest hydrogen content. Specimens of DMW Alloy 52 behaved in varying manner when tested with high hydrogen content, in both AW and PWHT conditions. PWHT seems to increase the tearing resistance of Alloy 182. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive Xray spectroscopy (EDS) were applied in order to examine the cracking path and to characterize the microstructural features affecting hydrogen trapping in Alloy 182 and 52 weld metals. A clear relation between high hydrogen content of the water, low fracture resistance values and intergranular/interdendritic type of fracture was observed, although also transgranular brittle-like fracture was observed in DMW Alloy 182 and all-weld metal Alloy 82 specimens tested in low temperature hydrogenated water. Hydrogen thermal desorption spectrometry (TDS) measurements were performed for Alloys 182 and 52 by using varying heating rates in order to study the effect of high temperature pre-exposure, different trapping sites and trapping activation energies. The high temperature pre-exposure was found to decrease the hydrogen content of Alloy 182 and 152 weld metals and consistently the fracture resistance values were increased. Different factors affecting the LTCP behaviour of nickel-based weld metals are discussed.",
    keywords = "nickel-based weld metal alloys, low temperature crack propagation, hydrogen trapping, fracture resistance",
    author = "Matias Ahonen and Ulla Ehrnst{\'e}n and Tapio Saukkonen and Olga Todoshchenko and Hannu H{\"a}nninen",
    note = "Project code: 102621 ; 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, ENVDEG 2015 ; Conference date: 09-08-2015 Through 12-08-2015",
    year = "2015",
    language = "English",

    }

    Ahonen, M, Ehrnstén, U, Saukkonen, T, Todoshchenko, O & Hänninen, H 2015, 'Factors affecting low temperature crack propagation (LTCP)', Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada, 9/08/15 - 12/08/15.

    Factors affecting low temperature crack propagation (LTCP). / Ahonen, Matias; Ehrnstén, Ulla; Saukkonen, Tapio; Todoshchenko, Olga; Hänninen, Hannu.

    2015. Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.

    Research output: Contribution to conferenceConference articleScientific

    TY - CONF

    T1 - Factors affecting low temperature crack propagation (LTCP)

    AU - Ahonen, Matias

    AU - Ehrnstén, Ulla

    AU - Saukkonen, Tapio

    AU - Todoshchenko, Olga

    AU - Hänninen, Hannu

    N1 - Project code: 102621

    PY - 2015

    Y1 - 2015

    N2 - The effect of hydrogenated PWR primary water on the Low Temperature Crack Propagation (LTCP) susceptibility of the nickel-based Alloy 182, 82, 152 and 52 weld metals was studied performing J-R tests for all-weld metal and dissimilar metal weld (DMW) mock-up specimens at a slow displacement rate in simulated low temperature PWR primary water. Single edge bend (SE(B)) specimens were tested in hydrogenated environments (100, 30 and 5 cm3 H2/kg H2O) with and without exposure to high-temperature hydrogenated PWR water prior to loading (24 h or 30 days at 300??C). Additionally, the effect of post-weld heat treatment on LTCP behaviour of Alloy 182 and 52 weld metals was studied. It was observed that Alloy 182 was the most susceptible material to LTCP, but also some specimens of Alloy 52 exhibited rather low JQ values, similar to those of Alloy 182, when tested with highest hydrogen content. Specimens of DMW Alloy 52 behaved in varying manner when tested with high hydrogen content, in both AW and PWHT conditions. PWHT seems to increase the tearing resistance of Alloy 182. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive Xray spectroscopy (EDS) were applied in order to examine the cracking path and to characterize the microstructural features affecting hydrogen trapping in Alloy 182 and 52 weld metals. A clear relation between high hydrogen content of the water, low fracture resistance values and intergranular/interdendritic type of fracture was observed, although also transgranular brittle-like fracture was observed in DMW Alloy 182 and all-weld metal Alloy 82 specimens tested in low temperature hydrogenated water. Hydrogen thermal desorption spectrometry (TDS) measurements were performed for Alloys 182 and 52 by using varying heating rates in order to study the effect of high temperature pre-exposure, different trapping sites and trapping activation energies. The high temperature pre-exposure was found to decrease the hydrogen content of Alloy 182 and 152 weld metals and consistently the fracture resistance values were increased. Different factors affecting the LTCP behaviour of nickel-based weld metals are discussed.

    AB - The effect of hydrogenated PWR primary water on the Low Temperature Crack Propagation (LTCP) susceptibility of the nickel-based Alloy 182, 82, 152 and 52 weld metals was studied performing J-R tests for all-weld metal and dissimilar metal weld (DMW) mock-up specimens at a slow displacement rate in simulated low temperature PWR primary water. Single edge bend (SE(B)) specimens were tested in hydrogenated environments (100, 30 and 5 cm3 H2/kg H2O) with and without exposure to high-temperature hydrogenated PWR water prior to loading (24 h or 30 days at 300??C). Additionally, the effect of post-weld heat treatment on LTCP behaviour of Alloy 182 and 52 weld metals was studied. It was observed that Alloy 182 was the most susceptible material to LTCP, but also some specimens of Alloy 52 exhibited rather low JQ values, similar to those of Alloy 182, when tested with highest hydrogen content. Specimens of DMW Alloy 52 behaved in varying manner when tested with high hydrogen content, in both AW and PWHT conditions. PWHT seems to increase the tearing resistance of Alloy 182. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive Xray spectroscopy (EDS) were applied in order to examine the cracking path and to characterize the microstructural features affecting hydrogen trapping in Alloy 182 and 52 weld metals. A clear relation between high hydrogen content of the water, low fracture resistance values and intergranular/interdendritic type of fracture was observed, although also transgranular brittle-like fracture was observed in DMW Alloy 182 and all-weld metal Alloy 82 specimens tested in low temperature hydrogenated water. Hydrogen thermal desorption spectrometry (TDS) measurements were performed for Alloys 182 and 52 by using varying heating rates in order to study the effect of high temperature pre-exposure, different trapping sites and trapping activation energies. The high temperature pre-exposure was found to decrease the hydrogen content of Alloy 182 and 152 weld metals and consistently the fracture resistance values were increased. Different factors affecting the LTCP behaviour of nickel-based weld metals are discussed.

    KW - nickel-based weld metal alloys

    KW - low temperature crack propagation

    KW - hydrogen trapping

    KW - fracture resistance

    M3 - Conference article

    ER -

    Ahonen M, Ehrnstén U, Saukkonen T, Todoshchenko O, Hänninen H. Factors affecting low temperature crack propagation (LTCP). 2015. Paper presented at 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, ENVDEG 2015, Ottawa, Canada.