Which statement about thread rolling is true?

Thread rolling is a manufacturing process that shapes threads on a workpiece by using dies to apply pressure and deform the material. This method involves two hard metal dies that are positioned in such a way that as the workpiece is fed between them, the dies rotate and compress the metal to form the threads. This process is advantageous because it maintains the integrity of the material, improves the mechanical properties through work hardening, and results in a strong and precise thread profile.

Using molten metal, as mentioned in other choices, is not associated with thread rolling; that process would pertain to casting or molding techniques rather than rolling. Likewise, the requirement for a single die is misaligned with the fundamentals of thread rolling, which typically necessitates a pair of dies for effective shaping. Finally, while some threading processes can have cosmetic benefits, thread rolling is primarily focused on creating functional threads that enhance the performance and reliability of fasteners in various applications.