Which manufacturing process is used to smooth over any microscopic cracks or pores within a connecting rod after manufacture?

Shot peening is the process that is used to improve the surface finish of a connecting rod by addressing microscopic cracks and pores that may be present after manufacturing. This technique entails bombarding the surface of the material with small spherical media (often steel or ceramic balls), which creates compressive residual stresses on the surface. These compressive stresses help to close up any small cracks or pores, thereby enhancing the durability, fatigue resistance, and overall performance of the connecting rod.

Using shot peening can help extend the life of components under cyclic loading conditions, making it particularly valuable in the automotive and aerospace industries where connecting rods experience significant stress during operation. This method not only smooths the surface but also refinishes it in a way that can enhance mechanical properties.

The other processes mentioned, like induction hardening, forging, and hammering, serve different purposes. Induction hardening is primarily a heat treatment process to increase hardness and wear resistance. Forging is a shaping process that involves deforming the material while it's heated or at room temperature, which improves strength through grain refinement but does not specifically address surface imperfections. Hammering is a technique used for shaping and strength enhancement through mechanical deformation but again does not focus on closing microscopic voids.