Sterling silver (as any other metal) can be shaped, bent, hammered etc. while it is cold. However these processes cause the metal to become work hardened. In order to make the metal workable again it needs to be annealed. At any process of bending, shaping, etc. large crystals are broken into smaller ones resulting in brittleness. In time, even at room temperature, crystals will realign themselves into an organized lattice. Annealing (heating) process accelerates the movement of atoms.