Papers by Author: W. R. Tyson

Abstract: CANMET-MTL has developed a low-constraint test designed to reduce unnecessary conservatism in the measurement of toughness for use in the assessment of flaws in pipeline girth welds. The design is based on tension loading using fixed (clamped) grips of a single-edge-notched BxB SE(T) specimen, side-grooved to promote plane-strain conditions. Equations have been developed to derive J-integral, CTOD and crack growth from measurement of load and crack-mouth opening displacement. Loading conditions (essentially distance between the grips) have been chosen to reproduce the crack-tip constraint of a circumferential surface flaw in a pipe in service under tensile or bending loads. In this paper, the development of the test and the principal findings from its use will be described.

Abstract: Tensile and compressive tests of a large AZ31 extrusion were performed along extrusion and long transverse directions over a range of strain rate (0.00075 s-1 to 9 s-1) and temperature (100°C to -143°C). The effects of strain rate, temperature, sample orientation and load direction (tension or compression) on mechanical properties are reported and discussed. The yield strength of tensile samples along the extrusion direction can be described by a constitutive equation using the conventional rate parameter for thermally activated deformation.

Abstract: Characterization of fracture toughness is discussed in relation to specification of steels for northern pipelines. The state of the art and research trends in measurement of CTOD for girth welds and CTOA for linepipe steel are described.