Hitachi Metals, Ltd.

Ryuuichiroh Sugano

Takaaki Sekiyama

Hideshi Nakatsu

Yousuke Nakano

Taishiroh Fukumaru

Hitoshi Kataoka

Mariko Fukumaru

Hidemitsu Horie

Yasuhiro Hosoda

Kouta Kataoka

A mold steel that is a steel having a composition containing, in terms of mass %: 0.07 to 0.15% of C; more than 0 and less than 0.8% of Si; more than 0 and not more than 1.0% of Mn; less than 0.05% of P; less than 0.02% of S; more than 0 and not more than 0.5% of Ni; more than 0 and less than 0.8% of Mo and W, either alone or as a complex (Mo+&#xbd;W); more than 0 and less than 0.15% of V; and 0.25 to 1.5% of Cu, with the balance consisting of Fe, Cr and unavoidable impurities, wherein the content of Cr is more than 4.9% and not more than 5.3% and the hardness of the mold steel is 30 to 42 HRC.

Die steel and method for producing same

A method for evaluating the corrosion-fatigue life of a steel material includes: bringing a corrosive medium into contact with a predetermined portion of the steel material; measuring strain on the steel material while applying cyclic loads to the steel material; measuring an N-th strain index from strain amplitude at the number of initial load applications and strain amplitude at the N-th load application (N is a natural number larger than the number of initial load applications); and estimating the corrosion-fatigue life of the steel material by comparing the N-th strain index with a previously certified life strain index.

Method for evaluating corrosion-fatigue life of steel material

Growing community of inventors

Yasugi, Japan

Ryuuichiroh Sugano