X-Ray - Form of radiant energy with wavelength shorter than that of visible light and with the ability to penetrate materials that absorb or reflect ordinary light. X-rays are usually produced by bombarding a metallic target with electrons in a high vacuum. In nuclear reactions it is customary to refer to photons originating in the nucleus as gamma rays and to those originating in the extranuclear part of the atom as x-rays.

X-Ray Crystallography - X-ray photographs of metals are a means of providing information which in many cases cannot be obtained by microscopic methods. The line produced by each element or phase are characteristic and their general pattern enables the crystalline structure to be identified. The scale of the pattern can be used to determine accurately the size of the unit cell and therefore the distance apart of the individual atoms. From the relative intensity of the lines it is possible to deduce the distribution throughout the unit cell, the various types of atoms in an alloy or the degree of preferred orientation in the material.

X-Ray Gauge Recorder - Equipment used to produce a gauge chart that records thickness measurements.

X-Ray Gauge Unit - Equipment used to measure thickness of steel. The unit is positioned across the width of the strip on the entry end of the line.

X-Rays - Light rays, excited usually by the impact of cathode rays on matter, which have wave lengths between about 10-6 cm, and 10-9 cm; also written X-rays, same as Roentgen rays.