Thermally Activated Crack Growth and Fracture Toughness Evaluation of Pipeline Steels Using Acoustic Emission

Abstract

The article presents an approach to assessing the fracture toughness of structural alloys based on thermally activated crack growth and recording acoustic emission signals. The kinetic and structural features of the stable growth of the initiated crack are estimated using a multilevel acoustic emission model based on the time dependence of the logarithm of the cumulative acoustic emission count. The article provides an evaluation of the stable kinetic constants included in the equation of the thermal fluctuation steps of a crack according to literature sources and using the acoustic emission method. It is shown that parameters such as activation energy, activation area before the crack tip, and the rate of non-activation crack growth are stable and show a satisfactory correspondence between the reference literature and real experiments. The approach does not require a set of laboratory experiments to determine the empirical constants of traditional crack growth rate equations, and it also differs in that it takes into account the unique features of the destruction of a particular specimen or technological equipment and allows for a non-destructive assessment of fracture toughness. The values obtained are conservative. The concentration criterion of destruction requires further investigation.

Research on Corrosion Detection Method of Oil Tank Bottom Based on Acoustic Emission Technology

“…Slight deformation occurs in corroded area on the bottom plate of metal storage tanks under load pressure, leading to cracking in corrosion layers and generation of acoustic emission signals. Additionally, eddy currents owing to leakage from oil tank's bottom plate also produce acoustic emissions [13][14][15][16][17]. When using AE technology for detecting oil tanks, a predetermined number of piezoelectric ceramic sensors are placed at a uniform angle along with a circumferential direction around a predetermined height (typically 20-40 cm) from the tank's bottom wall surface to capture signals originating from its bottom plate, as schematically shown in Figure 1.…”

Research on a Corrosion Detection Method for Oil Tank Bottoms Based on Acoustic Emission Technology

“…AE technology is widely used in engineering fields such as storage tanks, pipelines, rock formations and bridges, and its development cannot be separated from the construction of theoretical models [13][14][15][16][17]. The bottom of an oil tank can be regarded as a two-dimensional circular plate, as shown in Figure 2.…”

Evaluating the Effectiveness of Magnetic-Pulse Treatment for Healing Continuity Defects in the Metal of Oil and Gas Pipelines

“…One peculiarity of continuity defects is that these defects during loading cause a concentration of stresses near their tips, leading to a rapid increase in their number and geometric dimensions, followed by the merging of the latter and the formation of large discontinuities. As a result, the operational properties and service lifespan of structures located under the load decrease [5][6][7][8][9]. Additionally, the shape of the defect tips has proved to be a significant factor influencing the crack growth rate and the metal's fracture toughness.…”