Final answer:
A definite break in the material caused by excessive working of the metal during forging, rolling, or extruding is called a line defect. Line defects weaken the structure of solids and affect their mechanical properties. Dislocations play a crucial role in plastic behavior and are particularly important for structural materials like metals.
Step-by-step explanation:
A definite break in the material caused by excessive working of the metal during the forging, rolling or extruding operation is called a line defect.
Line defects, also known as dislocations, occur due to misalignment of ions or the presence of vacancies along a line. Movements of dislocations give rise to plastic behavior in materials.
Line defects weaken the structure of solids and affect their mechanical properties, which is why the formation and study of dislocations are important for materials like metals.