Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho (kobe Steel, Ltd.)

Kabushiki Kaisha Kobe Seiko Sho

Tomoko Sugimura

Koichi Sakamoto

Atsuhiko Yoshida

Sumie Suda

Sei Kimura

Yoshio Fukuzaki

Takeshi Inoue

Hidenori Nako

Masaki Shimamoto

Masaki Kaizuka

Keito Ishizaki

Hiroshi Yaguchi

Yosuke Shindo

Yoshitomi Okazaki

Mutsuhisa Nagahama

Tetsushi Deura

Yoshihiko Kitagawa

Katsuhiko Ozaki

Yimin Yuan

Kei Masumoto

Goro Anan

Akihiro Owaki

A solid wire for electroslag welding, including Fe and, by mass % based on a total mass of the wire: C: more than 0% and 0.03% or less; Si: more than 0% and 0.10% or less; Mn: more than 0% and 0.25% or less; Ni: 10.5%-14.0%; S: more than 0% and 0.010% or less; Al: more than 0% and 0.250% or less; REM: 0.002%-0.080%; and O: more than 0% and 0.0090% or less.

Solid wire for electroslag welding, and welding joint

Disclosed herein is an electroslag welding wire containing, by mass % based on total mass of the wire: C: more than 0% and 0.07% or less; Si: more than 0% and 0.50% or less; Mn: more than 0% and 1.0% or less; Ni: 6.0 to 15.0%; and Fe: 79% or more. The electroslag welding wire satisfies the following relationship (1): 0.150&#x2264;C+Si/30+Mn/20+Ni/60&#x2264;0.300 (1).

Wire for electroslag welding, flux for electroslag welding and welded joint

A Si-killed steel wire rod for obtaining a spring excellent in fatigue properties and a spring excellent in fatigue properties obtained from such steel wire rod are provided. In the Si-killed steel wire rod of the present invention, oxide-based inclusions present in the wire rod contain SiO: 30-90%, AlO: 2-35%, MgO: 35% or below (not inclusive of 0%), CaO: 50% or below (not inclusive of 0%), MnO: 20% or below (not inclusive of 0%) and BaO: 0.2-20% respectively, and total content of (CaO+MgO) is 3% or above.

Si-killed steel wire rod and spring

High cleanliness spring steel useful in manufacturing a spring with SiO-based inclusions being extremely controlled and excellent in fatigue properties is provided. High cleanliness spring steel which is steel containing;

High cleanliness spring steel and high cleanliness spring excellent in fatigue properties

Bearing steel material according to the present invention has: a properly adjusted chemical composition; an average chemical composition of oxide-inclusions which comprises 10 to 45% of CaO, 20 to 45% of AlO, 30 to 50% of SiO, up to 15% (exclusive of 0) of MnO, and 3 to 10% of MgO, with the balance being unavoidable impurities; a maximum major axis diameter of the oxide inclusions in a longitudinal section of the steel material of 20 &#x3bc;m or less; and a spheroidal cementite structure.

Bearing steel material with excellent rolling contact fatigue properties and a bearing part

A bearing steel material which contains 0.8-1.1 mass % C, 0.15-0.8 mass % Si, 0.1-1.0 mass % Mn, 1.3-1.8 mass % Cr, up to 0.05 mass % P (0 mass % is excluded), up to 0.015 mass % S (0 mass % excluded), 0.0002-0.005 mass % Al, 0.0002-0.0020 mass % Ca, 0.0005-0.010 mass % Ti, up to 0.0080 mass % N (0 mass % is excluded), and up to 0.0025 mass % O (0 mass % is excluded). The steel material contains oxide inclusions which have an average composition that comprises, in terms of mass %, 20-50% CaO, 20-50% AlO, 20-70% SiO, and 3-10% TiO.

Bearing steel material with excellent rolling fatigue property and bearing part

A Si-killed steel wire rod for obtaining a spring excellent in fatigue properties and a spring excellent in fatigue properties obtained from the steel wire rod are provided. The Si-killed steel wire rod of the present invention contains Sr: 0.03-20 ppm (means 'mass ppm', hereinafter the same), Al: 1-30 ppm and Si: 0.2-4% (means 'mass %', hereinafter the same) respectively, and contains Mg and/or Ca by a range of 0.5-30 ppm in total. Also, in the Si-killed steel wire rod of the present invention, oxide-based inclusions present in the wire rod contain SiO: 30-90%, AlO: 2-50%, MgO: 35% or below (not inclusive of 0%), CaO: 50% or below (not inclusive of 0%), MnO: 20% or below (not inclusive of 0%) and SrO: 0.2-15% respectively, and total content of (CaO+MgO) is 3% or above. A spring excellent in fatigue properties can be obtained by forming the spring from such steel wire rod.

Si-killed steel wire rod and spring excellent in fatigue properties

Disclosed is a spring steel which contains, by mass, 1.2% or less C; 0.1% to 2% Mn; 0.2% to 3% Si; 0.0003% to 0.005% Al; to 8 ppm Li; 30 ppm or less (excluding 0 ppm) Ca; and 10 ppm or less (excluding 0 ppm) Mg. The steel contains oxide inclusions satisfying the following conditions (1) to (3) in a number of 1&#xd7;10or more per square millimeter: (1) containing a total of 80 percent by mass or more of AlOand SiObased on the inclusion composition excluding LiO; (2) having a ratio by mass of AlOto SiOof from 1:4 to 2:3; and (3) containing lithium (Li). The spring steel gives a spring that exhibits superior fatigue properties without strict control of the average composition of inclusions.

Spring steel and spring superior in fatigue properties

High cleanliness spring steel useful in manufacturing a spring with SiO-based inclusions being extremely controlled and excellent in fatigue properties is provided.

An object of this invention is to provide a steel for high-cleanliness spring which is useful for the production of a spring excellent in fatigue characteristics in high Si steels. The steel for high-cleanliness spring with excellent fatigue characteristics according to the invention contains: in terms of mass %, C: 1.2% or less (excluding 0%); Si: 1.8% to 4%; Mn: 0.1% to 2.0%; and total Al: 0.01% or less (excluding 0%), with the remainder being iron and inevitable impurities, in which the Si amount and a solute (SIMS) Ca amount in the steel satisfy a relationship of the following expression (1):Si&#xd7;10&#x2266;solute (SIMS) Ca&#x2266;Si&#xd7;5&#xd7;10&#x2003;&#x2003;(1)(in which each of the solute (SIMS) Ca and Si represents the amount thereof (mass %) in the steel).

Steel for high-cleanliness spring with excellent fatigue characteristics and high-cleanliness spring

The present invention provides a low-carbon resulfurized free machining steel product excellent in machinability typified by finished surface roughness even though toxic Pb or special elements such as Bi or Te are not added, and a suitable production method thereof. A steel product has a specific composition, has contents of Mn and S satisfying the following conditions: 0.40&#x2266;Mn*S&#x2266;1.2 and Mn/S&#x2267;3.0, and contains a ferrite-pearlite structure as the metallographic structure, in which the average width (&#x3bc;m) of sulfide inclusions in the steel product is 2.8*(log d) or more, wherein d (mm) is the diameter of the steel product, and pro-eutectoid ferrite in the metallographic structure has a hardness HV of 133 to 150 or a difference in deformation resistance at a strain of 0.3 between 200&#xb0; C. and 25&#xb0; C. is 110 MPa or more and 200 MPa or less, the deformation resistances being determined in a compression test at a deformation rate of 0.3 mm/min.

Low carbon composite free-cutting steel product excellent in roughness of finished surface and method for production thereof

The present invention relates to a high-cleanliness steel having a high fatigue strength and high cold workability, and a method of making the high-cleanliness steel. The method adds a Li&#x2014;Si alloy having a Li content between 20 and 40% and/or LiCOas a Li-containing substance to a molten steel. The Li-containing substance is added to the molten steel after the completion of a series of steps of a ladle refining process including composition adjustment, temperature adjustment and slag refining. The high-cleanliness steel has a total-Li content between 0.020 and 20 ppm by mass and contains 1.0 or below oxide inclusion particle having a major diameter of 20 &#x3bc;m or above at a maximum in 50 g of the steel wire. The steel contains an oxide inclusion that has a CaO content between 15 and 55%, SiOcontent between 20 and 70%, an AlOcontent of 35% or below, a MgO content of 20% or below and a LiO content between 0.5 and 20%. The high-cleanliness steel has improved fatigue characteristics and improved cold workability.

Method for producing high cleanness steel excellent in fatigue strength or cold workability

Method for producing high cleanliness steel excellent in fatigue strength or cold workability

Disclosed herein is an ultra clean spring steel which contains inclusions easily elongated and broken into fine particles by hot rolling and which is easily adaptive to cold rolling and yields springs excelling in fatigue characteristics. The spring steel is characterized in that the wire contains oxide inclusions with a sulfur concentration no more than 10 mass % such that no less than 70% (in terms of numbers) of such inclusions, which exist in the outer layer outside one quarter of the diameter of the wire and have a width no smaller than 3 &#x3bc;m, satisfies the formula (1) below,CaO+AlO+SiO+MnO+MgO&#x3e;80 (mass %) . &#x2003;&#x2003;(1)

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Kobe, Japan

Tomoko Sugimura