How can the yield strength of regular yellow brass be improved?

Cold working is a process that involves deforming a metal at temperatures below its recrystallization point. When yellow brass is cold worked, it undergoes strain hardening (also known as work hardening), which increases its yield strength. This occurs because the dislocation density within the metal increases as the material is deformed, making it more difficult for dislocations to move and thus enhancing the material's strength.

Using cold working to improve yield strength is particularly advantageous for materials like yellow brass, as this process not only increases strength but can also improve other properties, such as hardness and resistance to wear. Moreover, cold working is typically a practical and efficient method used in manufacturing processes, as it can be integrated into various shaping and forming operations.

In contrast, tempering and heat treatment are processes used primarily for ferrous alloys or certain other alloys to achieve particular microstructural properties and are not applicable in the same way to yellow brass. Chill casting pertains to a method of molding metals, which affects the solidification process rather than the mechanical properties directly associated with yield strength. Thus, cold working is the most effective method among the choices for enhancing the yield strength of yellow brass.