Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Toshiharu Aiso

Kei Miyanishi

Suguru Yoshida

Manabu Kubota

Masayuki Hashimura

Shuji Kozawa

Atsushi Mizuno

Hajime Saitoh

A steel for induction hardening according to an aspect includes, as a chemical composition, predetermined amounts of alloy elements and a remainder including Fe and impurities, in which Al&#xd7;N is 0.000330 to 0.000825, Mn/S is 4.6 to 14.0, a machinability index M is 15.5 to 25.65, an area fraction of AlN having an equivalent circle diameter of more than 200 nm at a &#xbc; position of a diameter of the steel is 20% or less of an area fraction of all AlN having an equivalent circle diameter of 40 nm or more, and a number density of Mn sulfide-based inclusions having a maximum diameter of 0.3 &#x3bc;m or more and 10 &#x3bc;m or less at the &#xbc; position of the diameter is 100 pieces/mmor more and 2500 pieces/mmor less.

Steel for induction hardening

A steel for an induction hardening including, by mass %, C: more than 0.75% to 1.20%, Si: 0.002 to 3.00%, Mn: 0.20 to 2.00%, S: 0.002 to 0.100%, Al: more than 0.050% to 3.00%. P: limited to 0.050% or less, N: limited to 0.0200% or less, O: limited to: 0.0030% or less, and the balance composing of iron and unavoidable impurities, wherein an Al content and a N content satisfy, by mass %, Al&#x2212;(27/14)&#xd7;N&#x3e;0.050%.

Steel for induction hardening roughly shaped material for induction hardening

Steel for machine structure use excellent in tool lifetime in a broad range of cutting speeds regardless of continuous machining, intermittent machining, or other systems and further in various machining environments such as use of a cutting fluid or a dry, semidry, and oxygen enriched environment, having a chemical composition containing, by mass %, C: 0.01 to 1.2%, Si: 0.005 to 3.0%, Mn: 0.05 to 3.0%, P: 0.0001 to 0.2%, S: 0.0001 to 0.35%, N: 0.0005 to 0.035%, and Al: 0.05 to 1.0%, satisfying [Al %]&#x2212;(27/14)&#xd7;[N %]&#x2267;0.05%, and having a balance of Fe and unavoidable impurities and forming an AlOcoating on the surface of a cutting tool by machining using a cutting tool coated on the surface contacting the machined material by metal oxides with a value of a standard free energy of formation at 1300&#xb0; C. of that value of AlOor more, and a machining method of the same.

Steel for machine structure use excellent in cutting tool lifetime and machining method of same

In the method of cutting steel for machine structural use, steel for machine structural use, in which chemical components contain, by mass %, 0.01% to 1.2% of C, 0.005% to 3.0% of Si, 0.05% to 3.0% of Mn, 0.001% to 0.2% of P, 0.001% to 0.35% of S, 0.002% to 0.035% of N and 0.05% to 1.0% of Al, in a case in which [Al%] and [N%] represent the mass % of Al and N in the steel respectively, [Al%]&#x2212;(27/14)&#xd7;[N%]&#x2267;0.05% is satisfied, is the other elements are included as necessary, and a balance consisting of Fe and inevitable impurities, is used, and a cutting process is carried out on the steel for machine structural use using water-insoluble cutting oil in which the amount of dissolved oxygen is 4 volume % to 16 volume %.

Method of cutting steel for machine structural use

This steel for a machine structure contains, in mass %: C: 0.40% to less than 0.75%; Si: 0.01% to 3.0%; Mn: 0.1% to 1.8%; S: 0.001% to 0.1%; Al: more than 0.1% and not more than 1.0%; N: 0.001% to 0.02%; and P: limited to not more than 0.05%, with a balance including Fe and inevitable impurities, in which the steel satisfies 139.38&#x2266;214&#xd7;[C]+30.6&#xd7;[Si]+42.8&#xd7;[Mn]&#x2212;14.7&#xd7;[Al]&#x2266;177 and 0.72&#x2266;[C]+1/7&#xd7;[Si]+1/5&#xd7;[Mn]&#x3c;1.539.

Steel for machine structure exhibiting excellent machinability

A steel for an induction hardening including, by mass %, C: more than 0.75% to 1.20%, Si: 0.002 to 3.00%, Mn: 0.20 to 2.00%, S: 0.002 to 0.100%, Al: more than 0.050% to 3.00%, P: limited to 0.050% or less, N: limited to 0.0200% or less, O: limited to: 0.0030% or less, and the balance composing of iron and unavoidable impurities, wherein an Al content and a N content satisfy, by mass %, Al&#x2212;(27/14)&#xd7;N&#x3e;0.050%.

Steel for induction hardening, roughly shaped material for induction hardening, producing method thereof, and induction hardening steel part

The present invention provides a carburized steel part obtained by subjecting a base material to a cutting operation and a carburizing operation, in which the base material includes chemical components of: C: greater than 0.3 but less than or equal to 0.6% by mass; Si: 0.01 to 1.5% by mass; Mn: 0.3 to 2.0% by mass; P: 0.0001 to 0.02% by mass; S: 0.001 to 0.15% by mass; N: 0.001 to 0.03% by mass; Al: greater than 0.06 but less than or equal to 0.3% by mass; and, O: 0.0001 to 0.005% by mass, with a balance including iron and inevitable impurities, and in which the carburized steel part has a hardness of HV550 to HV800 in a surface layer portion, and a hardness of HV400 to HV550 in a core portion.

Carburized steel part

The cutting method of steel for machine structural use includes: forming a mist by mixing a cutting fluid supplied at a supply rate of 0.01 ml/hour to 200 ml/hour and an oxidizing gas containing, by volume %, 21% to 50% of oxygen; and cutting the steel for machine structural use while the mist is blown on the cutting edge surface of a tool and the surface of the steel for machine structural use, wherein the steel for machine structural use includes, by mass %: C: 0.01% to 1.2%, Si: 0.005% to 3.0%, Mn: 0.05% to 3.0%, P: 0.001% to 0.2%, S: 0.001% to 0.35%, N: 0.002% to 0.035%, Al: 0.05% to 1.0%, and the balance consisting of Fe and inevitable impurities in which O is limited to 0.003% or less, and the amount of Al [Al %] and the amount of N [N %] satisfy [Al %]&#x2212;(27/14)&#xd7;[N %]&#x2267;0.05.

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Tokyo, Japan

Toshiharu Aiso