As a first step, a literature survey was undertaken on HIC (Hydrogen Induced Cracking) phenomena. Material and metallurgical parameters were investigated, in addition the various testing environments and criteria used for FFP (fit-for-purpose) testing were assessed. The literature sources suggested a variety of methodologies that can be used for FFP HIC testing. However, a universally applicable FFP test method was not identified. Therefore, an experimental study was launched to establish a suitable methodology and to better define the key parameters involved in HIC phenomena. Experiments consisted of HIC exposure tests based on the NACE TM 0284-2003 Standard method. Parameters studied were pH (3.5 to 5.5), H2S partial pressure (10 and 100 mbar), and time of exposure (96 hours and 2 weeks). Characterisation included hydrogen content measurement and HIC cracking evaluation both by ultrasonic testing and metallographic examination. From the HIC exposure tests, for specimens tested at a level of 10 mbar H2S no HIC was observed and the free hydrogen content remained below 1.5 mg/100g. However, all specimens tested at a level of 100 mbar exhibited HIC, the most severe being for the tests at pH 3.5. The measured free hydrogen content reached 2.5 mg/100g at pH 3.5. Ultimate tensile and metallographic tests showed a very good consistency of results in the detection and evaluation of cracking. These results are very encouraging and suggest that a 'region of environmental severity' diagram, similar to that developed for sulfide stress cracking incorporated into NACE MR0175/ISO 15156, can be developed for the HIC resistance of steels. This will relate the HIC resistance to the environmental severity defined by the partial pressure of H2S and the pH. This diagram will enable the mapping of HIC according to cracking susceptibility and will help in defining the 'HIC sour service' limits for line-pipe steels. Work is in progress on a range of steels (both 'sweet' and 'sour' service grades for a range of yield strength levels) to further develop this domain diagram.


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    Titel :

    Hydrogen induced cracking (HIC) assessment of low alloy steel linepipe for sour service application - laboratory testing


    Weitere Titelangaben:

    Beurteilung der wasserstoffinduzierten Rissbildung von Leitungsrohren aus niedriglegiertem Stahl für den Sauergaseinsatz - Laborprüfung


    Beteiligte:
    Kittel, J. (Autor:in) / Martin, J.W. (Autor:in) / Cassagne, T. (Autor:in) / Bosch, C. (Autor:in)


    Erscheinungsdatum :

    2007


    Format / Umfang :

    13 Seiten, 9 Bilder, 6 Tabellen, 6 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




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