ASTM E 82/E82M : 2014

1.1This test method covers the back-reflection Laue procedure for determining the orientation of a metal crystal. The back-reflection Laue method for determining crystal orientation may be applied to macrograins and micrograins depending on the beam size within polycrystalline aggregates, as well as to single crystals of any size. This test method is described with reference to cubic crystals and other structures such as: hexagonal, tetragonal, or orthorhombic crystals.

1.2Most natural crystals have well developed external faces, and the orientation of such crystals can usually be determined from inspection. The orientation of a crystal having poorly developed faces or no faces at all (for example, a metal crystal prepared in the laboratory) shall be determined by more elaborate methods. The most convenient and accurate of these involves the use of X-ray diffraction. The “orientation of a metal crystal” is known when the positions in space of the crystallographic axes of the unit cell have been located with reference to the surface geometry of the crystal specimen. This relation between unit cell position and surface geometry is most conveniently expressed by stereographic or gnomonic projection.

1.3Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.4This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.