Trace Element Control, Nickel Alloy, Cobalt Alloy, and Iron Alloy Wrought Products, for High-Temperature, High-Stressed Applications
This specification establishes maximum permissible limits for elements not normally specified but which may occur in trace amounts in wrought nickel, cobalt, and iron alloy products. Primarily for highly-stressed rotating parts, such as turbine discs, where control of trace elements is required to maintain elevated-temperature tensile, stress-rupture, creep, and low-cycle fatigue properties. It is intended that this specification be invoked only for selected applications by stipulation on drawings, purchase orders, or other documentation supplementing the material specification, or in material specifications. This specification covers four classes of trace element control, defined by the elements to be controlled as follows: Class 1 - Lead, Bismuth; Class 2 - Lead, Bismuth, Selenium; Class 3 - Lead, Bismuth, Selenium, Silver, Tin; Class 4 - Lead, Bismuth, Selenium, Silver, Tin, Thallium, Tellurium, Arsenic. When trace element control is required, the elements to be controlled shall be indicated by this specification number and the appropriate class number. For example, AMS 2281, Class 1 will indicate that control of lead and bismuth is required.