CHARACTERIZATION OF TEXTURE AND RESIDUAL-STRESS IN A SECTION OF 610 MM PIPELINE STEEL

Gas pipelines are inspected for defects such as corrosion. The most co mmonly used nondestructive inspection tool uses the magnetic flux leak age (MFL) technique, The MFL signals depend on the magnetic behaviour of the pipe, which is sensitive to its microstructure and crystallogra phic texture as well as both residual and applied stresses. Here a sec tion of commercial X70 pipeline is characterized using microstructural examination, X-ray diffraction (to determine crystallographic texture ) and neutron diffraction (for residual stress measurement). The resul ts correlate well with the manufacturing steps used for this type of p ipe. Magnetic characterization is also performed using magnetic Barkha usen noise measurements, which reflect the magnetic anisotropy in the pipe and thus the MFL signal. These results do not correlate simply wi th crystallographic texture and residual strain results, but this is n ot unexpected given the complex nature of the material and its stress state.