Kobe Steel, Ltd.

Shinsuke Masuda

Koichi Sakamoto

Hiroshi Yaguchi

Shogo Murakami

Koichi Akazawa

Motohiro Horiguchi

Takehiro Tsuchida

Tomokazu Masuda

Mutsuhisa Nagahama

Masaki Shimamoto

The present invention provides a steel for machine and structural use which sustains mechanical properties such as strength by reducing S content, and exerts excellent machinability (in particular, tool life) in both of intermittent cutting with HSS tools and continuous cutting with carbide tools. The invention relates to a steel for machine and structural use which contains an oxide inclusion containing, wherein a total mass of an average composition of the oxide inclusions is 100%: CaO: 10 to 55 mass %; SiO: 20 to 70 mass %; AlO: more than 0 and 35 mass % or less; MgO: more than 0 and 20 mass % or less; MnO: more than 0 and 5 mass % or less; and one or more members selected from the group consisting of LiO, NaO, KO, BaO, SrO and TiO: 0.5 to 20 mass % in total.

Steel for machine and structural use having excellent machinability

The present invention provides a steel for machine and structural use which is capable of maintaining mechanical characteristics such as strength by reducing a S content as well as of exhibiting excellent machinability (particularly tool life) in intermittent cutting (such as hobbing) with the high speed tool, and a method useful for producing the steel for machine and structural use. The steel for machine and structural use according to the invention secures 0.002% or more of solute N in the steel and has a chemical composition which is appropriately adjusted and satisfies a relationship of the following expression (1): (0.1&#xd7;[Cr]+[Al])/[O]&#x2267;150 . . . (1), in which [Cr], [Al], and [0] represent a Cr content (mass %), an Al content (mass %), and an O content (mass %), respectively.

Steel for machine and structural use having excellent machinability and process for producing the same

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Kobe, Japan

Shinsuke Masuda