Since 12L14 is an extraordinary machining steel it has become the favorite carbon metal for machining-especially on light weight lathes. It offers inherent ductility combined with finer surface quality. 12L14 has a smooth cold finish (rolled) surface.
1 An infection in the middle ear. When the middle ear is infected, pressure builds up and pushes against the eardrum and can cause the eardrum to perforate. When that happens, you may suddenly notice that the pain and pressure you've felt from the infection stops and pus drains from the ear.  An injury to the eardrum.
Bleeding or fluid discharge from the ear canal. Ringing noise in the ear. The level of hearing loss depends on the size of the perforation and what caused it. Trauma to the ear or head can injure the middle ear, inner ear or both, and can cause severe hearing loss. If an explosion has torn the eardrum, you may have ringing in your ears (tinnitus) for several days, as well as hearing loss. If the perforated eardrum becomes infected, the hearing loss may worsen.