| 摘要 |
PROBLEM TO BE SOLVED: To provide a metal plate for a security door, which can enhance a security function of the door, and which can surely prevent intrusion from being caused by using a drill. SOLUTION: This metal plate for the security door is composed of stainless steel with a Vickers' hardness of 400 HV or more. Rigid particles are exposed on the surface of the metal plate, and/or a rigid layer is formed on the surface of the metal plate. Preferably, the rigid layer, which is formed on the surface of the metal plate, is an auto-oxidized layer. Desirably, such a type of stainless steel as to be turned into martensite by quenching, in which the content of C is in the range of 0.05-2.5 mass%, is used as the stainless steel. COPYRIGHT: (C)2008,JPO&INPIT
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