Abstract: Disclosed is a zirconium alloy material having high corrosion resistance regardless of thermal history during its manufacturing process. The zirconium alloy material is obtained by providing a zirconium alloy containing on the mass basis: 0.001% to 1.9% of Sn, 0.01% to 0.3% of Fe, 0.01% to 0.3% of Cr, 0.001% to 0.3% of Ni, 0.001% to 3.0% of Nb, 0.027% or less of C, 0.025% or less of N, 4.5% or less of Hf and 0.16% or less of O with the remainder being inevitable impurities and zirconium, being formed of a bulk alloy and a surface layer, in which the surface layer has a plastic strain of 3 or more or a Vickers hardness of 260 HV or more and an arithmetic mean surface roughness Ra of 0.2 ?m or less.

Abstract: A process of forming an ultrafine crystal layer in a workpiece constituted by a metallic material. The process includes: performing a machining operation on a surface of the workpiece, so as to impart a large local strain to the machined surface of the workpiece, where the machining operation causes the machined surface of the workpiece to be subjected to a plastic working that causes to have large local strain in the form of a true strain of at least one, such that the ultrafine crystal layer is formed in a surface layer portion of the workpiece that defines the machined surface of the workpiece. Also disclosed are a nanocrystal layer forming process, a machine component having the ultrafine crystal layer or the nanocrystal layer, and a machine component producing process of producing the machine component.

Abstract: Disclosed is a zirconium alloy material having high corrosion resistance regardless of thermal history during its manufacturing process. The zirconium alloy material is obtained by providing a zirconium alloy containing on the mass basis: 0.001% to 1.9% of Sn, 0.01% to 0.3% of Fe, 0.01% to 0.3% of Cr, 0.001% to 0.3% of Ni, 0.001% to 3.0% of Nb, 0.027% or less of C, 0.025% or less of N, 4.5% or less of Hf and 0.16% or less of O with the remainder being inevitable impurities and zirconium, being formed of a bulk alloy and a surface layer, in which the surface layer has a plastic strain of 3 or more or a Vickers hardness of 260 HV or more and an arithmetic mean surface roughness Ra of 0.2 ?m or less.

Abstract: A process of forming an ultrafine crystal layer in a workpiece constituted by a metallic material. The process includes: performing a machining operation on a surface of the workpiece, so as to impart a large local strain to the machined surface of the workpiece, where the machining operation causes the machined surface of the workpiece to be subjected to a plastic working that causes to have large local strain in the form of a true strain of at least one, such that the ultrafine crystal layer is formed in a surface layer portion of the workpiece that defines the machined surface of the workpiece. Also disclosed are a nanocrystal layer forming process, a machine component having the ultrafine crystal layer or the nanocrystal layer, and a machine component producing process of producing the machine component.

Abstract: An ultrafine crystal layer forming process of forming an ultrafine crystal layer in a workpiece constituted by a metallic material. The process includes: performing a machining operation on a surface of the workpiece using a machining tool, so as to impart a large local strain to the machined surface of the workpiece, where the machining operation using the machining tool causes the machined surface of the workpiece to be subjected to a plastic working that causes to have large local strain in the form of a true strain of at least 1, such that the ultrafine crystal layer is formed in a surface layer portion of the workpiece that defines the machined surface of the workpiece. Also disclosed are a nanocrystal layer forming process, a machine component having the ultrafine crystal layer or the nanocrystal layer, and a machine component producing process of producing the machine component.

Abstract: This invention relates to a method for fining a surface of a metal product to form crystal grains having sizes less than 1 ? m at their surfaces and the metal product produced thereby. The method is comprised of a process for forming crystal grains having sizes less than 1 ? m at the surface of the metal product by projecting or peening shots or projectiles while a power per unit of area of the surface, which power is caused by projecting or peening shots or projectiles, is controlled at a predetermined value.