To avoid the initiation of a crack in a pipeline it is of great interest to know the CTOD (Crack Tip Opening Displacement) values. There are two main possibilities to stop a crack in a pipeline: The first one is to apply special crack arrestors, and the second one is to use a material with a high crack-arrest toughness. This paper deals with the determination of CTOD values according to BS 7448 using three point bend specimens and CA (Crack-Arrest Fracture-Toughness) values using three-point bend specimens (test proposal of TVFA), compact-crack-arrest specimens (ASTM E 1221), and full-thickness compact-crack-arrest specimens (test proposal of Crosley and Ripling). The problems in determining the crack tip opening displacement and crack-arrest fracture-toughness are discussed in detail, the results are compared. Finally the different resulting fracture mechanical values, as for example CTOD values and CA (Crack-Arrest) values etc., of the welds (welding metals and heat-affected zones) are compared with each other and with the values of the base material. The tested materials were the base material, the weld metal, and the heat-affected zone of welds, using different welding processes, as Shielded Metal Arc Welding, Gas Metal Arc Welding, or Submerged Arc Welding, of the pipeline steels X70 and X80, according to API 5L, and the stainless duplex-steel 1.4462. This paper contains a comment on the differences between the crack-arrest toughness values of the three materials and a comparison of the three applied test methods.
Fracture mechanical values of modern pipeline-steels
Welding in the World ; 50 , 1/2 ; 52-61
2006
10 Seiten, 12 Bilder, 27 Quellen
Aufsatz (Zeitschrift)
Englisch
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