Figure 4 Grain Orientation (a) Random (b) Preferred

GRAIN STRUCTURE AND BOUNDARY DOE-HDBK-1017/1-93 Structure of Metals Another important property of the grains is their orientation. Figure 4(a) represents a random Figure 3 Grains and Boundaries (a) Microscopic (b) Atomic arrangement of the grains such that no one direction within the grains is aligned with the external boundaries of the metal sample. This random orientation can be obtained by cross rolling the material. If such a sample were rolled sufficiently in one direction, it might develop a grain-oriented structure in the rolling direction as shown in Figure 4(b). This is called preferred orientation. In many cases, preferred orientation is very desirable, but in other instances, it can be most harmful. For example, preferred orientation in uranium fuel elements can result in catastrophic changes in dimensions during use in a nuclear reactor. Figure 4 Grain Orientation (a) Random (b) Preferred MS-01 Page 10 Rev. 0