FATIGUE MEASUREMENT OF METAL MATERIAL

PURPOSE: To measure the degree of fatigue of a metal material accurately by shooting the diffraction images of a plurality of different regions from a sample to be measured by limited visual field electron ray diffraction and obtaining the average value of the deviation angle of a measured azimuth. CONSTITUTION: The diffraction images of a plurality of different regions are shot from a sample to be measured by a limited visual field electron ray diffraction and the average value of the deviation angle of a measured azimuth is obtained. The average value is compared with that of the deviation angle of the azimuth for each stage from a degree of fatigue of 0 to 100% that is obtained in advance, thus measuring the degree of fatigue of the sample to be measured. Then, the average value of the deviation angle of the azimuth of the diffraction image obtained by the limited visual field electron ray diffraction increases linearly proportionately with the increase in the degree of fatigue and the degree of damage. Also, the difference in the average value between an area near a crack and a part that is away from it is small at a degree of fatigue of 100%. Therefore, the degree of fatigue can be accurately measured without depending on the sample location of the sample.