Purpose This specification covers the requirements for electroless nickel deposited on various materials. Application This deposit has been used typically to provide a uniform build-up on intricate shapes@ to improve wear and/or corrosion resistance@ or to improve solderability on or for selected materials@ but usage is not limited to such applications. The deposit has been used in service up to 1000 ??(538 ?? although wear and/or corrosion resistance may degrade as service temperature increases. Application of electroless nickel plating to steel parts having a hardness of 46 HRC (ultimate tensile strength of 220 ksi (1517 MPa) or higher shall not be performed unless authorized by the design documentation or specific approval has been received from the cognizant engineering organization. Classification Plating covered by this specification is classified as follows: Class 1: Except for hydrogen embrittlement relief@ no post plating thermal treatment. Class 2: Thermal treatment at 450 ??(232 ?? or above to harden the deposit. Class 3: Thermal treatment at 375 ??(191 ?? to improve adhesion for nonheat-treatable aluminum alloys and beryllium alloys. Class 4: Thermal treatment at 250 ??(121 ?? to improve adhesion for heat-treatable aluminum alloys. Unless a specific class is specified@ Class 1 shall be supplied. Safety - Hazardous Materials While the materials@ methods@ applications@ and processes described or referenced in this specification may involve the use of hazardous materials@ this specification does not address the hazards which may be involved in such use. It is the responsibility of the user to ensure familiarity with the safe and proper use of any hazardous materials and to take necessary precautionary measures to ensure the health and safety of all personnel involved.