What is a common effect of the quenching process?

The quenching process, which involves rapidly cooling metal, typically enhances its mechanical properties, particularly by improving tensile strength. When a hot metal piece is quenched, the rapid temperature drop transforms its microstructure, usually resulting in the formation of a harder and more brittle phase known as martensite, especially in steels. This change increases the metal's resistance to deformation, allowing it to withstand higher tensile loads before breaking.

While other options such as increasing heat resistance and achieving a uniform grain structure can be related to specific heat treatment processes, they are not common primary effects of quenching. Malleability, on the other hand, is characterized by a material's ability to deform under compressive stress and typically decreases after a quenching treatment.

Thus, enhancing tensile strength is the most significant and relevant outcome of the quenching process, making it the correct choice.