140CPU67160 include requirements for diffusion barrier, undercoat, electrical conductivity and wear and corrosion protection in specialized environments. 4.2.3 SC1 Light Service, 5 µm—This is defined by a minimum coating thickness of 5 µm for extending the life of the part. Typical environments include light-load lubricated wear, indoor corrosion protection to prevent rusting, and for soldering and mild abrasive wear. 4.2.4 SC2 Mild Service, 13 µm—This is defined by mild corrosion and wear environments. It is characterized by industrial atmosphere exposure on steel substrates in dry or oiled environments. 4.2.5 SC3 Moderate Service, 25 µm—This is defined by moderate environments such as non marine outdoor exposure, alkali salts at elevated temperature, and moderate wear. 4.2.6 SC4 Severe Service, 75 µm—This is defined by a very aggressive environment. Typical environments would include acid solutions, elevated temperature and pressure, hydrogen sulfide and carbon dioxide oil service, high-temperature chloride systems, very severe wear, and marine immersion. NOTE 2—The performance of the autocatalytic nickel coating depends to a large extent on the surface finish of the article to be plated and how it was pretreated. Rough, non uniform surfaces require thicker coatings than smooth surfaces to achieve maximum corrosion resistance and minimum porosity. 4.3 Post Heat Treatment Class—The nickel-phosphorus coatings shall be classified by heat treatment after plating to increase coating adhesion and or hardness (see Table 3). 4.3.1 Class 1—As-deposited, no heat treatment. 4.3.2 Class 2—Heat treatment at 260 to 400°C to produce a minimum hardness of 850 HK100. 4.3.3 Class 3—Heat treatment at 180 to 200°C for 2 to 4 h to improve coating adhesion on steel and to provide for hydrogen embrittlement relief (see section 6.6). 4.3.4 Class 4—Heat treatment at 120 to 130°C for at least 1 h to increase adhesion of heat-treatable (age-hardened) aluminum alloys and carburized steel (see Note 3). 4.3.5 Class 5—Heat treatment at 140 to 150°C for at least 1 h to improve coating adhesion for aluminum, non agehardened aluminum alloys, copper, copper alloys and beryllium. 4.3.6 Class 6—Heat treatment at 300 to 320°C for at least 1 h to improve coating adhesion for titanium alloys. NOTE 3—Heat-treatable aluminum alloys such as Type 7075 can undergo microstructural changes and lose strength when heated to over 130°C. 5. Ordering Information 5.1 The following information shall be supplied by the purchaser in either the purchase order or on the engineering drawing of the part to be plated: 5.1.1 Title, ASTM designation number, and year of issue of this specification. 5.1.2 Classification of the deposit by type, service condition, class, (see 4.1, 4.2 and 4.3). 5.1.3 Specify maximum dimension and tolerance requirements, if any. 5.1.4 Peening, if required (see 6.5). 5.1.5 Stress relief heat treatment before plating, (see 6.3). 5.1.6 Hydrogen Embrittlement Relief after plating, (see 6.6). 5.1.7 Significant surfaces and surfaces not to be plated must be indicated on drawings or sample. 5.1.8 Supplemental or Special Government Requirements such as, specific phosphorus content, abrasion wear or corrosion resistance of the coating, solderability, contact resistance and packaging selected from Supplemental Requirements. 5.1.9 Requirement for a vacuum, inert or reducing atmosphere for heat treatment above 260°C to prevent surface oxidation of the coating (see S3). 5.1.10 Test methods for coating adhesion, composition, thickness, porosity, wear and corrosion resistance, if required, selected from those found in Section 9 and Supplemental Requirements. 5.1.11 Requirements for sampling (see Section 8). NOTE 4—The purchaser should furnish separate test specimens or coupons of the basis metal for test purposes to be plated concurrently with the articles to be plated (see 8.4). 6. Materials and Manufacture 6.1 Substrate—Defects in the surface of the basis metal such as scratches, porosity, pits, inclusions, roll and die marks, laps, cracks, burrs, cold shuts, and roughness may adversely affect the appearance and performance of the deposit, despite the observance of the best plating practice. Any such defects on significant surfaces shall be brought to the attention of the purchaser before plating. The producer shall not be responsible for coatings defects resulting from surface conditions of the metal, if these conditions have been brought to the attention of the purchaser. 6.2 Pretreatment—Parts to be au |
