Ultrasonic Cleaning
Immersion cleaning aided by ultrasonic waves which cause microagitation.
Ultrasonic Testing
A nondestructive method of testing metal for flaws based on the fact that ultrasonic waves are reflected and refracted at the boundaries of a solid medium. Ultrasonic testing is used to detect flaws in materials.
Undercooling
See Supercooling.
Undercut
Part of a mold or die requiring a drawback. See Drawback.
Unkilled Steel
A wild steel insufficiently deoxidized so that it evolves gas and blowholes during solidification. See Killed Steel.
Upgrading
In castings, the removal and repair of discontinuities to raise the quality level of the casting beyond that which can be economically achieved by good foundry practice. See Casting, Foundry.
Upper Yield Point (Also Yield Point)
Denoted in yield point phenomenon as a distinct break from the elastic region accompanied by a drop in load, yet prior to plastic deformation in the stress-strain curve in a low-carbon steel.
Upset
An addition to any flask part to increase height or depth.
Urea Formaldehyde Resin
A thermosetting product of condensation from urea or thio-urea and formaldehyde, soluble in water and used as a sand binder in core and mold compounds.
