6913G623C100015

Small Business Innovation Research Program (SBIR) Phase II

NDT of Fracture Toughness for Pipeline Steels

NDT of Fracture Toughness for Pipeline Steels3/16/2018Ultrasound-based technology to nondestructively determine fracture toughness of pipeline steels will be developed. Fracture toughness is the material parameter that, along with applied loading and flaw geometry, dictates the critical crack size, and therefore controls the flaw size that must be detected during inspections. A major challenge facing pipeline operators is that many pipelines are old, making their structural integrity uncertain, and that material pedigree of the pipeline steel is unknown. Therefore, operations must be based on minimum values of the material parameters. The probability that actual fracture toughness is higher than the minimum is reasonably high, which means that pipelines are operating below capacity. Nondestructive determination of fracture toughness by ball indentation has not sufficiently solved the problem. Nonlinear features of ultrasonic wave propagation are sensitive to material nonlinearities, associated with microstructure (based on composition and processing), that dictate fracture toughness. Prior results indicate that ultrasonic nonlinearity is related to fracture appearance transition temperature, which in turn is related to fracture toughness. Herein, wave interaction of two circumferential guided waves will be used to generate nonlinear features (in a completely nondestructive way) that will be related to the fracture appearance transition temperature obtained from Charpy V-notch impact tests.

The goal of phase II is to continue the R&D efforts initiated in Phase I. Funding is based on the results achieved in Phase I and the scientific and technical merit and commercial potential of the project proposed in Phase II.

180PH1

180PH1004-IIB

6913G618QSBIR1

Steven Owens