Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Fracture Toughness Testing of a Pressure Vessel Steel Using Clamped SE(T) Specimens and the Normalization Method
Submission Author:
Vitor Scarabeli Barbosa , RJ
Co-Authors:
Vitor Scarabeli Barbosa, Felipe Ezsias Fiumarelli, Claudio Ruggieri
Presenter: Vitor Scarabeli Barbosa
doi://10.26678/ABCM.COBEM2021.COB2021-0606
Abstract
Much current research now centers on the utilization of single edge notched tension, SE(T), specimens (also often termed SENT configurations) under fixed-grip conditions to measure experimental crack growth resistance (J-Delta_a ) curves (also termed R-curves) as the crack-tip stress and strain fields which drive the fracture process in this crack configuration are similar to the corresponding fields at weld circumferential flaws in pipeline girth welds. Recent and on-going work to develop testing procedures for clamped SE(T) specimens focus on the evaluation of J-resistance curves based on the unloading compliance (UC) method using a single specimen. However, while used effectively in routine fracture testing programs for ductile materials, the UC method can become highly problematic when it is not feasible to measure crack extension during the test, such as in aggressive environments or under high loading rate and high test temperatures. In an effort to simplify the crack growth resistance test procedure, an alternative test protocol, commonly known as the normalization method, for directly determining a J-resistance curve from load versus displacement records has also been employed as an effective procedure to produce crack growth resistance curves which are equivalent to J-Delta_a data derived from the UC method. However, the methodology relies heavily on accurate values of load, crack size, and displacement experimentally measured at the end of the test, which, in turn, can introduce large uncertainty in the resulting fitting of the normalized load-displacement curve. This work explores the use of the normalization method to determine crack growth resistance curves for a typical pressure vessel steel. A primary objective is to verify the effectiveness of the methodology in providing accurate descriptions of the ductile properties for the tested materials using low constraint fracture specimens under predominantly tensile loading. Fracture toughness testing conducted on an A285 Gr C pressure vessel steel provides the load-displacement data from which J-resistance curves are evaluated on the basis of the normalization procedure. For the tested pressure vessel steel, the normalization method produces ductile tearing responses in terms of J-Delta_a curves which are in good agreement with experimentally measured crack growth responses derived from the UC procedure.
Keywords
fracture toughness test, SE(T) specimen, crack growth resistance curve, normalization method, pressure vessel steel
