Electromagnetic test for microstructure anomalies such as alpha-case,

Abstract

An electromagnetic or eddy-current test for microstructure anomalies such as alpha-case in titanium alloys, and for carbide precipitates and untempered and overtempered martensite in steel alloys. The inspection is designed to provide an accurate, reproducible, cost effective, and nondestructive approach to detect and isolate discrepant parts exhibiting an unsatisfactory microstructural condition. The test method utilizes high frequency eddy-current test equipment, having an eddy-current test probe and a display screen, on a reference metallurgical standard to establish a reference level trace signal of phase amplitude response therefor on the display screen. The high frequency eddy-current test equipment is then utilized on a metallurgical sample being tested for the presence of the deleterious structural condition, to derive a trace signal of phase amplitude response therefor on the display screen. The level of the trace signal of phase amplitude response screen for the reference standard is compared on the display with the level of the trace signal amplitude response for the metallurgical sample being tested, to determine if the metallurgical sample has the particular deleterious condition for which it is being tested. The test method can use both acceptable and nonacceptable reference metallurigical standards to establish reference level trace signals of phase amplitude response therefor on the display screen.