best ultrasonic testing sequence for a large steel shaft

[Tmoose]

We make rotating machines with steel shafts of various sizes up to about 12 inch diameter and over 8 feet long. Recently a shaft was rejected for physical test results yield strength below the 50 ksi spec.

The shaft supplier often procures the material (we specify 1045 Normalized, with certs) and supplies the finished shaft.
Since the recent rejection the supplier considers himself having been "burnt" and has proposed buying steel shaft blanks in lots and ultrasonic testing them.

I don't see how UT is going to detect material with low physical properties. Nonetheless the conversation now is about whether a second UT needs to be done as a rough machined blank, or perhaps even on the finished product.
My amateur opinion is that the uneven surface of a rough turned or finished part might be harder to test, and machining processes are only capable of causing surface defects that are best detected by mag-particle inspection anyhow.

 

[JR97]

Tmoose,

You are correct for traditional ultrasonic testing which is performed to detect material defects and discontinuities. There is no reason to repeat these tests at later stages in processing.

I have heard of a new technique in which the sound velocity is accurately measured and used as a predictor for tensile strength. I believe it is used primarily in castings versus your bar stock application, but technology may have evolved beyond what I know.

Here is a link I found in a quick Google search:

http://www.egmrs.org/EJS/PDF/vo242/133.pdf

JR0097