METAL STRUCTURES STRESSED AND STRAINED STATE MAGNETIC INSPECTION BY IN-02 THE SCANNING METAL STRAIN INDICATOR

Abstract

Scanning metal strain indicator IN-02 instrument structure and outlines of operation based on residual magnetic field measurement above surface of steel part with metal under stress-strain state is described. A number of representative modes of information acquired, describing the stressed state of metal, are provided in the metal strain indicator IN-02 PC software application. Investigations carried on steel specimens have artificially made local areas with increased level of stress-strain state of metal resulted to relatively high magnetoelastic sensitivity of IN-02 instrument (relative to magnetic structurescopes series KRM-C). The circumstance given is shown to allow inspect stress-strain state by metal strain indi-cator IN-02 even if significant thickness of protective coating layer presented on the surface of metal. Several practical examples of steel parts and constructions stress-strain state magnetic inspection by metal strain indicator IN-02 in regular industrial conditions are also resulted. The magnetic inspections of stressed state of steel pipeline are resulted to contour plots, where closed contours encircle the local areas with increased level of stress-strain state of metal. The local areas with increased level of stress-strain state of metal are usually located on the pipe surface near the welds and have an arbitrary shape and size, varying from tens of millimeters to tens of centimeters. Further investigations suggested that the main cause of local areas with increased level of stress-strain state of steel pipes detected is residual stress of metal.