Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Teruyuki Wakatsuki

Hiroshi Kita

Suguru Yoshida

Hirokazu Sugiyama

Kazuo Fujita

Yasushi Horiuchi

Takeshi Hioki

Hiroyuki Hasegawa

Akira Inagaki

Toshihiro Ishibashi

Yasushi Takeshima

Teruhisa Okumura

Masao Kurokawa

Hiroaki Hadano

Yoshimi Toriyama

Kazutoshi Ichikawa

Noriaki Onodera

Kohichi Yamamoto

This H-beam steel contains, in mass %, C, Si, Mn, Al, Ti, N, O, Nb, and B. The H-beam steel has composition in which the amount of Nb and the amount of B satisfy, in mass %, 0.070&#x2266;Nb+125B&#x2266;0.155, and has a metal structure in which, in a microstructure, an area fraction of bainite is not less than 70%, a total of an area fraction of pearlite and an area fraction of cementite is not more than 15%, and the remainder is at least one of ferrite and island martensite. The effective crystalline-grain size of the bainite is not more than 40 &#x3bc;m, and the thickness of a flange falls in a range of 12 to 40 mm.

High-strength H-beam steel exhibiting excellent low-temperature toughness and method of manufacturing same

A steel material superior in high temperature characteristics and toughness is provided, that is, a steel material containing, by mass %, C: 0.005% to 0.03%, Si: 0.05% to 0.40%, Mn: 0.40% to 1.70%, Nb: 0.02% to 0.25%, Ti: 0.005% to 0.025%, N: 0.0008% to 0.0045%, B: 0.0003% to 0.0030%, restricting P: 0.030% or less, S: 0.020% or less, Al: 0.03% or less, and having a balance of Fe and unavoidable impurities, where the contents of C and Nb satisfyC&#x2014;Nb/7.74&#x2266;0.02and Ti-based oxides of a grain size of 0.05 to 10 &#x3bc;m are present in a density of 30 to 300/mm.

Steel material superior in high temperature characteristics and toughness and method of production of same

The present invention provides a high strength thick steel material excellent in toughness and weldability reduced in amount of C and amount of N, containing suitable amounts of Si, Mn, Nb, Ti, B, and O, having contents of C and Nb satisfying C&#x2014;Nb/7.74&#x2266;0.004, having a density of Ti-containing oxides of a particle size of 0.05 to 10 &#x3bc;m of 30 to 300/mm, and having a density of Ti-containing oxides of a particle size over 10 &#x3bc;m of 10/mmor less, produced by treating steel by preliminary deoxidation to adjust the dissolved oxygen to 0.005 to 0.015 mass %, then adding Ti and, furthermore, vacuum degassing the steel for 30 minutes or more, smelting it, then continuously casting it to produce a steel slab or billet, heating the steel slab or billet to 1100 to 1350&#xb0; C., hot rolling the slab or billet to a thickness of 40 to 150 mm, then cooling it.

High strength thick steel material and high strength giant H-shape excellent in toughness and weldability and methods of production of same

An apparatus for cooling thin-webbed H-beam steel includes means for forcibly spray cooling the flanges of the H-beam in intermediate and final hot rolling zones. The cooling is based upon tracking information with respect to predetermined positions along the length of the H-beam. A plurality of flow quantity control blocks are disposed in parallel with each having a three way valve having a water supply side port, a nozzle side port, and a water drain port. A plurality of on-off valves connect the nozzle side port to nozzles in a nozzle group to select nozzles based upon the flange width of the H-beam. A variable throttle mechanism maintains pressure loss at the water drain side equal to pressure loss at the nozzle side. Switching of the three way valve of one flow quantity control block can be carried out without affecting other flow quantity control blocks.

Apparatus for cooling thin-webbed H-beam steel

A thin-webbed H-beam steel having a web thinner that flanges is produced by forcibly water cooling the outer surface of the flanges during an intermediate hot rolling prior to a final hot rolling by cooling to less than 700.degree. C., interrupting the cooling to return the temperature to greater than 700.degree. C., and repeating the cooling and interrupting in order to refine the microstructure of the surface of the flanges to a predetermined depth from the surface; final-hot rolling the intermediate-hot rolled H-beam steel; and forcibly water cooling the flanges of the final-hot rolled H-beam steel in a manner such that the web does not wave during this forcible water cooling, and such that upon completion of the forcible water cooling, thermal stress, generated in the web during air cooling to room temperature, does not exceed the buckling strength of the web.

Process for producing thin-webbed H-beam steel

Growing community of inventors

Tokyo, Japan

Teruyuki Wakatsuki