0434516 J. Indacochea Univ. Illinois, Chicago
This study intends to establish a viable method to measure creep damage of low alloy ferromagnetic steels used at elevated temperatures, by using a magnetoelastic sensor developed at UIC. A basic relationship between magnetoelastic phenomena and structural changes within the ferromagnetic materials will be developed to assess creep. By understanding the role of microstructure changes on the material's magnetic response, adjustments to the sensor design can be made to enhance its sensitivity. Creep testing is performed on several samples pertaining to two types of ferromagnetic steels; systematically the corresponding magnetic responses of each sample will be measured using the sensor. A calibration curve of "creep-magnetic response" will be produced to evaluate the progressive magnetic behavior of the ferromagnetic steels in relation to creep damage. The metallurgical changes of the ferromagnetic materials are characterized by light, scanning, and transmission electron microscopy with EDS, x-ray diffraction and microhardness measurements. Issues surrounding domestic energy supply and protection against infrastructure disturbances demand a closer evaluation and real time system monitoring of materials to ensure reliability. A practical method to measure creep damage of low alloy ferromagnetic steels is expected to result. Development of NDE devices to evaluate the materials status is key to extending the service life of energy producing systems.
