In metallurgy, which property is usually a measure of a metal's ability to stretch without breaking?

Ductility is the property that indicates a metal's ability to undergo significant plastic deformation before rupture or fracture, which directly relates to its ability to stretch without breaking. This characteristic is especially important in applications where materials must withstand forming processes like drawing or elongation. Ductility allows metals to be shaped into desired forms without losing integrity, making it a critical property in manufacturing and engineering.

Understanding ductility involves recognizing its significance in various metallurgical and structural applications. For instance, materials with high ductility can absorb energy and deform under stress, making them less likely to fail catastrophically. This is contrasted with other properties such as tensile strength, which measures the maximum stress a material can withstand while being stretched or pulled before breaking, but does not specify the extent to which it can deform.

Similarly, thermal expansion refers to how a material expands when heated, while hardness measures a material's resistance to deformation or indentation. Neither of these properties directly assesses a material's ability to stretch without breaking in the way that ductility does. Therefore, ductility is the most relevant measure when evaluating how much a metal can be stretched before failure occurs.