Hitachi, Ltd.

Yosio Kanekiyo

Akira Minato

Tutomu Shimizu

A martensitic stainless steel to be used for the impellers of turbo-blowers, compressors and the like consisting essentially, based on weight of 0.04 - 0.15% C, up to 2.0% Si, 0.2 - 2.0% Mn, 3.5 - 6.0% Ni, 10 - 16% Cr, and at least one element selected from the group consisting of 0.5 - 3.0% Mo, 0.01 - 0.8% Nb, and the balance being Fe. The amounts of .delta.-ferrite therein is not more than 10%. The steel may further contain up to 0.2% additional element or elements, i.e., N, Al, Ti, Ca, and/or a rare-earth element or elements. The steel of this composition offers high strength, great toughness, and good weldability and, when annealed after welding, it will display the same properties as after quenching and tempering. Impellers made of this steel are for heavy-duty, high-efficiency applications.

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Tsuchiura, Japan

Yosio Kanekiyo