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Article Dans Une Revue Journal of Failure Analysis and Prevention Année : 2016

Use of a Ring DWTT Specimen for Determination of Steel NDT from Pipe of Diameter Less than DN500

Résumé

It has become recognized that the drop weight tearing test (DWTT) energy better represents the ductile fracture resistance of pipe steels since it utilizes a specimen that has the full thickness of the pipe and has a fracture path long enough to reach steady-state fracture resistance. However, the API 5L code does not require it for pipe sizes less than DN500. The aim of this paper is: to propose a DWTT specific to small diameter pipes based on a new specimen, the Ring Drop Weight Tearing Test (RDWTT) specimen, to evaluate the transition temperature T t, DWTT and nil ductility temperature (NDT) of the pipe steel API5L X65, to introduce the transition temperature T t, DWTT in the Transition Temperature Material Master Curve (TTMC) of the API5L X65 steel, to compare the prediction of the crack ductile extension in a pipe based on the RDWTT's energy and crack tip opening angle (CTOA) in the case of the steel API5L X65. 1.INTRODUCTION The Drop Weight Tear Test (DWTT) is an impact test used primarily to determine the nil ductility transition temperature or NDT of ferritic steels. The test consists of subjecting the specimen to a single impact load at a progression of selected temperatures. The impact load is delivered by a guided, free-falling weight with energy of 340 to 1630 J according to the yield strength of the steel to be tested. A stop is employed to prevent deflection of more than a few millimeters. In accordance with the API RP 5L3 specification [1], the DWTT specimens have a size of 76.2 mm × 305 mm × B (B is pipe thickness) in the transverse-longitudinal (T-L) direction. A pressed notch, a chevron notch or an electrical discharge wire-cut notch is machined into the specimens. It has become recognized that the DWTT better represents the ductile fracture resistance of pipe steels since it utilizes a specimen that has the full thickness of the pipe and has a fracture path long enough to reach steady-state fracture resistance. When plotting the DWTT fracture energy versus temperature, one distinguishes the following types of fracture: Brittle initiation followed by brittle propagation at temperature T< FITT Ductile initiation followed by brittle propagation for FITT < T < FTE Ductile initiation followed by ductile propagation for FTE< T < FPT Plastic collapse T> FPT
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hal-02972662 , version 1 (20-10-2020)

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M Ben Amara, Julien Capelle, Z Azari, G Pluvinage. Use of a Ring DWTT Specimen for Determination of Steel NDT from Pipe of Diameter Less than DN500. Journal of Failure Analysis and Prevention, 2016, 16 (6), pp.941-950. ⟨10.1007/s11668-016-0194-y⟩. ⟨hal-02972662⟩
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