Which of the following techniques is NOT associated with strengthening metals?

Extruding is a manufacturing process where a material is pushed through a die to create a specific cross-sectional profile. While extrusion can certainly shape metals and is a manufacturing technique associated with producing components, it is not inherently a method for strengthening metals. This process primarily involves shaping and forming rather than altering the metal's crystalline structure or improving its mechanical properties.

In contrast, techniques like quenching, forging, and sintering are directly linked to the strengthening of metals. Quenching involves rapidly cooling a metal after it has been heated, which can harden the metal by trapping carbon in a solution. Forging, which involves shaping metal through compressive forces, improves its grain structure and enhances strength. Sintering involves compacting and heating powdered metal to create a solid piece, which can improve inter-particle bonds and overall strength.

Thus, while all options relate to metal processing, only extrusion does not focus on strengthening the material.