Which list contains common mechanical properties for fasteners?

The selection of tensile strength, hardness, and proof load as common mechanical properties for fasteners is correct because these properties are fundamental to evaluating and utilizing fasteners effectively in various applications.

Tensile strength measures the maximum amount of tensile (pulling) stress a material can withstand before failure. This is crucial for fasteners, as they need to endure forces without breaking, especially when holding components together under load.

Hardness indicates a material's resistance to deformation, which is important for fasteners that will undergo wear or require the ability to be driven into materials without stripping. It ensures that the fastener maintains its shape and integrity during installation and use.

Proof load is a specific level of load that a fastener can withstand without permanent deformation. Knowledge about proof load helps users choose the right fastener for the required application, ensuring safety and reliability in engineering projects.

In contrast, while yield strength and ductility are important mechanical properties, they are not necessarily unique to fasteners and may not be as commonly referred to in the context of their typical use. Fatigue limit is also relevant but is not as universally considered when defining fastener properties. Corrosion resistance, density, and thermal expansion are more related to a fastener's performance in environmental conditions