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.
If severe injury (e.g., skull fracture) moves the bones in the middle ear that send out sound, out of place, or injuries the inner ear, hearing loss may be serious. If the perforated eardrum is caused by a sudden traumatic or violent event, the loss of hearing can be great and tinnitus (ringing in the ear) may occur.