SYSTEM FOR EVALUATION OF SENSITIZATION DEGREE OF MATERIAL BY ACCELERATED STRESS CORROSION CRACK TEST

PROBLEM TO BE SOLVED: To obtain a system by which the soundness and the remaining life of a structure are evaluated quickly and accurately by directly carrying out a stress corrosion test by using a sampled material inside a furnace or by using a test piece for degradation monitoring. SOLUTION: As test pieces which are used for an accelerated stress corrosion crack test, a part of an actual-machine structure, a test piece for monitoring, a remaining material after a breaking test, a structure waste material after a replacement construction and a material for evaluation, which is inserted in advance into an actual-machine structure are used. The materials are worked as various test pieces in a hot laboratory for test-piece working. The test pieces are exposed to a state loaded with a set load in a high-temperature and high-pressure environment whose water quality, electric conductivity and corrosion potential are made more severe that those of an actual-machine environment. Then, various change states at this time are monitored sequentially, and the sensitization degree of the materials is evaluated. A fundamental curve is established in advance. The condition of the accelerated stress corrosion crack test is compared with a condition in the actual-machine environment. On the basis of the result of the accelerated stress corrosion crack test, a crack progress behavior in the actual machine environment is evaluated. Finally, an allowable dimension in a mechanical evaluation test or in a designing operation is compared with a crack progress estimation. Thereby, the remaining life of an apparatus structure is evaluated.