As quality demands for steel castings continually increase, delivering the desired quality economically remains a challenge. Foundries have traditionally used radiography for quality testing. The reliance on this technique stems from its visual nature and historical precedent. For medium to large steel castings, radiography can become expensive. The expense results from the shielding, regulator requirements and acquisition cost of the highly radioactive source needed when penetrating six inches of steel. Ultrasonic testing (UT) can provide significant cost savings over radiography, because it has significantly fewer safety requirements and costs less than a high energy x-ray source.

Adoption of UT has been limited by several factors. First, many customers perceive UT as less reproducible than x-ray inspection. This attitude has formed because UT output is a line scan, not the image associated with radiography. Some customers relate that they prefer the ability to archive x-ray films to maintain quality records. Second, surface roughness affects the ability of UT to detect defects; however, little data exists on the magnitude of this effect in castings and none exists for steel castings.1,2 As a result many foundries machine or grind casting surfaces before UT inspection, which increases cost. There are foundries that have found appropriate equipment and couplants to perform UT on as cast surfaces; however, there is no documentation on how this affects detection limits. The most significant factor is that the majority of foundries and foundry customers have extensive experience with radiography ratings and casting performance. No correlation between radiography and ultrasonic ASTM ratings presently exists. Therefore, no one is sure how ASTM UT ratings correlate with casting performance or radiography.

The goal of the project is to determine the repeatability of UT inspection on steel castings. Additionally, the project will correlate UT ratings to radiographic ratings. This will assist foundries in understanding UT and enable them to appropriately use the technology.

Status Update: The UT test cast plates have been cast and are now being sent out for round-robin testing for UT and x-ray. Anyone interested in how they might participate in this project should contact Prof. Bob Tuttle, Saginaw Valley State University, at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .