Hitachi, Ltd.

Toyohashi University of Technology

Univance Corporation

Minoru Umemoto

Yoshikazu Todaka

Masahisa Inagaki

Hideo Soneda

Naoya Okizaki

Ryo Ishibashi

Tadashi Suzuki

Tomomi Nakamura

Toshiichi Ota

Akihiro Yamashita

Shuji Tanaka

Hiroaki Azuma

Nozomu Adachi

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 &#x3bc;m or less.

Zirconium alloy material

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.

Process of forming nanocrystal layer

Growing community of inventors

Toyohashi, Japan

Minoru Umemoto