STEEL BACK PLATE FOR USE IN FRICTION MATERIAL, AND METHOD OF PRODUCING STEEL PRODUCT

摘要

PROBLEM TO BE SOLVED: To provide a steel back plate of excellent corrosion resistance and adhesion, for use in a friction material.;SOLUTION: The steel product has a nitride compound layer and a nitrogen-diffused layer formed on the surface layer of a base material being a steel. The nitride compound layer comprises a first compound layer formed on the nitrogen-diffused layer and a second compound layer formed on the surface of the first compound layer. The first compound layer is of an ε structure mainly constituted of Fe₃N, and the second compound layer has a higher nitrogen content than the first compound layer and has a surface comprising recessed parts and protruding parts formed thereon, wherein the uneven surface of the second compound layer includes recessed parts with a depth of at least 0.5 μm at such a high density as to be at least 3 locations per 50 μm of the nominal length. The surface layer formed on the steel has excellent surface adhesion and corrosion resistance. Thus, the nitride compound layer of excellent adhesion, an extremely low carbon content, and high corrosion resistance can be formed.;COPYRIGHT: (C)2013,JPO&INPIT