Ultrasonic Steel Cleanliness System

It is well known that nonmetallic inclusions can adversely affect the metallurgical properties of engineering alloys. For critical components such as aircraft engine gears and bearings it is important then to quantitatively assess the severity of the inclusion content in the alloy material before performing costly manufacturing operations. This poster paper will describe the operation and the initial results of a computer controlled steel cleanliness inspection system.The severity of the inclusion content is determined by this system through a statistical analysis of the internally reflected ultrasonic indications from the alloy material as a transducer is scanned in a raster fashion. These indications are sorted by a computer with respect to signal amplitude and location in the material. The initial results from a sampling of known clean and dirty steel billets show that the amplitude distribution function for the ultrasonic indications from clean material is nearly a normal distribution while the same distribution function for material with high nonmetallic inclusion content is highly skewed. Work has just started which will determine how well the ultrasonic cleanliness data from bar stock material will correlate with the mechanical performance of helicopter gears manufactured from this stock. The initial results will be presented.