Research And Application Of A Portable Thermoelectric Power Nondestructive Testing Device

Due to the excellent comprehensive performance,stainless steel materials have been widely used in various fields including chemical engineering,construction,marine equipment,aerospace and other fields.Therefore,it is of great significance to evaluate the in-service properties of stainless steel materials.Usually,non-destructive testing is essential for the stainless steel materials employed in specific situations.As a promising non-destructive testing technology,the measurement of thermoelectric power(TEP)could be used for the fine characterization of the microstructure evolution of the stainless steel materials.Compared with other non-destructive testing techniques,TEP measurement exhibits higher sensitivity to the changes in the microstructure of the materials,contributing to high accuracy and simple measurement process.Furthermore,the measurement of TEP is completely independent of the geometry of the materials.Based on these fascinating properties,it will be promising to develop a TEP nondestructive testing device for the performance evaluation of stainless steel materials.In this work,we firstly summarized the existing non-destructive testing techniques,followed by the discussion of their advantages and limitations as well as the testing principle and the applications.On this basis,a portable thermoelectric power non-destructive testing device was designed and fabricated,which consisted of box body,probe assembly and installation component.The measurement of TEP was achieved by the two probe components,while the installation component enabled the utilization of the device for different testing objects.Additionally,a corresponding circuit system was designed according to the requirements of the device.The as-designed system could be divided into five modules,including power supply module,signal acquisition module,motor control module,temperature control module and command module.The device was controlled by the upper computer through the organic combination of the five modules,thus completing the construction of the device circuit system.The measurement software of the device was developed by LabVIEW,realizing all the functions required for the device with stable operation,beautiful interface and user friendliness.To investigate the reliability of the device,a comparative test of Constantan was conducted with the commercial testing system and the device in this work with low RSDs,confirming the good reliability of this device.On this basis,the device was used for non-destructive measurement of 304 stainless steel samples in different aging conditions.It was found that the measurement results were in good agreement with the changes in the microstructure and mechanical properties of the samples,which proved the usability and practicability of the device.