The Charpy test is used to measure what property of materials?

The Charpy test is specifically designed to measure the toughness of materials. Toughness refers to a material's ability to absorb energy and plastically deform without fracturing. The test involves striking a notched specimen with a swinging hammer and measuring the energy absorbed by the specimen during fracture. This energy value is indicative of the material's toughness, illustrating how well it can withstand impact loads.

The other properties listed—hardness, ductility, and fatigue limit—are assessed using different types of tests. For example, hardness tests evaluate a material's resistance to indentation or penetration, ductility tests assess the extent to which a material can stretch or deform under tensile load, and fatigue limit involves subjecting a material to repeated loading cycles to determine the maximum stress it can withstand without failing. Therefore, the Charpy test uniquely focuses on toughness, making it the appropriate choice in this context.