Improvements in or relating to inspection of metals for defects

It is stated that defects in steel and Ti alloy components caused by machining or overheating during forging are normally detected by chemical etching of the surface followed by microscopic examination. This, however, is time consuming and generally inconvenient, and the use of acids for etching may lead to a loss of fatigue strength through hydrogen embrittlement. In the method described for inspection of the surface of a metal for defects material is removed from the surface by ion bombardment in a vacuum chamber or an Ar atmosphere, followed by microscopic examination. The ions used for bombardment are preferably inert, and the method does nor cause loss of fatigue strength. The depth of metal removed is normally not more than 100 A. The material may be cooled during bombardment by circulation of a liquid coolant. (U.K.)