METHOD FOR EVALUATING DEGREE OF FATIGUE DAMAGE OF METAL

• Main Authors: FUKUOKA CHIE, KIHARA SHIGEMITSU, YOSHIZAWA KOKI, MORISHIMA KEIKO
• Format: Patent
• Language: English
• Published: 07.08.1998
• Edition: 6
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; NUCLEAR ENGINEERING; NUCLEAR PHYSICS; NUCLEAR REACTORS; PHYSICS; TESTING

PROBLEM TO BE SOLVED: To easily evaluate the degree of the fatigue damage of the metallic material of the bainite structure by using the electron back side reflection analysis (EBSP) in the measurement of the azimuth difference between cells. SOLUTION: The azimuth difference between cells is measured by the electron back side reflection analysis method (EBSP) using a test piece which is sampled from a part to be measured and polished, and the mapping indication thereof is performed by the prescribed angle, and the histogram of the distribution of the azimuth difference by the prescribed angular step is prepared. The test piece is corroded, and the critical angle is determined from the observation results of the grain boundary by the optical microscope, and the azimuth difference to indicate the grain boundary identical or approximately close thereto, and the angular mean value at the azimuth difference below the critical angle is obtained from the formula of the histogram on the assumption that the azimuth difference of the grain boundary at the angle smaller than the critical angle is generated by the fatigue damage. The degree of the fatigue damage is evaluated using the thus-obtained mean intergranular angle. For this purpose, it is necessary to obtain the relationship between the known degree of the fatigue damage and the mean intergranular angle for the same material.