High temperature damage evaluation method of weld heat-affected zone

摘要

PURPOSE:To evaluate the degree of high temperature damage by applying a potential difference ratio or the difference of potential differences between an input component and an AC compo nent having the same frequency and phase as that of the input component to a previously formed diagram indicating relation between the potential difference ratio or the difference of potential differences and the degree of high temperature damage. CONSTITUTION:An AC signal having the sine wave of an optional frequency band is generated from an AC oscillator 11 built in a lock-in amplifier 10 and amplified by a power amplifier 12 and the amplified signal is impressed from a current input terminal to a part between a base material part 1a and a welding part 2. Electric signals from potential difference measur ing terminals 5, 6 are respectively amplified by a power amplifier 15 respectively through a signal switching circuit 14 and detected 10 by using a signal from the oscillator 11 as a reference signal, signals other than the electric signal having the same frequency and phase as that of the oscillation signal are removed and the inter-terminal potential difference of only the electric signal having the same frequency and phase as that of the oscillation signal is measured. Then, the potential difference ratio or difference of potential difference between an welding heat influenced part 3 and the base material part 1a is applied to the damage evaluating diagram indicating the relation between the potential difference ratio or the differ ence of potential differences and the degree of high temperature damage, the degree of thigh temperature damage of the influenced part 3 can be evaluated.