Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Canon Kabushiki Kaisha

Masaharu Ueda

Teruhisa Miyazaki

Takuya Tanahashi

Kouichi Uchino

Hideaki Kageyama

Katsuya Iwano

Akira Kobayashi

Kenichi Karimine

Koji Babazono

Ken Kutaragi

Takeshi Yamamoto

Takashi Morohoshi

Jun Takahashi

Kazuo Fujita

Kazunori Seki

Koichiro Matsushita

Akira Kida

Suguru Yoshida

Takuya Sato

Masahiro Sugimoto

Akio Okubo

Seiji Sugiyama

Kazuo Sugino

Kenji Saita

Noriaki Onodera

Takuya Satou

Yusuke Maeda

Hideo Tottori

Kyohei Sonoyama

Koichi Uchino

Takuya Satoh

Toshiya Kuroki

According to one aspect of the present invention, what is provided is a rail including, by mass %: C: 0.75% to 1.20%; Si: 0.10% to 2.00%; Mn: 0.10% to 2.00%; Cr: 0.10% to 1.20%; V: 0.010% to 0.200%; N: 0.0030% to 0.0200%; P≤0.0250%; S≤0.0250%; Mo: 0% to 0.50%, Co: 0% to 1.00%; B: 0% to 0.0050%; Cu: 0% to 1.00%; Ni: 0% to 1.00%; Nb: 0% to 0.0500%; Ti: 0% to 0.0500%; Mg: 0% to 0.0200%; Ca: 0% to 0.0200%; REM: 0% to 0.0500%; Zr: 0% to 0.0200%; Al: 0% to 1.00%; and a remainder consisting of Fe and impurities, in which a structure ranging from an outer surface of a head portion as an origin to a depth of 25 mm includes 95% or greater of a pearlite structure by area ratio, the hardness of the structure is in a range of Hv 360 to 500, and in ferrite of the pearlite structure at a position at a depth of 25 mm from the outer surface of the head portion as the origin, the number density of a V nitride having a grain size of 0.5 to 4.0 nm and including Cr is in a range of 1.0×10to 5.0×10cm.

Rail and method of manufacturing rail

A rail including a predetermined chemical composition is provided, in which 90 area % or greater of a metallographic structure in a cross section of a rail web portion is a pearlite structure, a minimum value of a hardness in the cross section of the rail web portion is Hv 300 or greater, and a difference between a maximum value and the minimum value of the hardness in the cross section of the rail web portion is Hv 40 or less.

Rail

A rail according to an aspect of the present invention is manufactured by melting steel using an electric furnace, satisfies a predetermined range as a chemical composition and particularly includes Pb: 0.0003% to 0.0020%, 95 area % or more of a region from an outer surface of a head portion to a depth of 20 mm is a pearlite structure, and a hardness in the region from the outer surface of the head portion to the depth of 20 mm is in a range of Hv 300 to Hv 500.

A rail provided by the present invention includes: has a predetermined chemical components, wherein, in a region from a head surface constituted of a surface of a top head portion and a surface of a corner head portion to a depth of 10 mm, a total amount of pearlite structures and bainite structures is 95% by area or more, and an amount of the bainite structures is 20% by area or more and less than 50% by area, and an average hardness of the region from the head surface to a depth of 10 mm is in a range of Hv 400 to Hv 500.

Rail and production method therefor

An object of the present invention is to provide a heat treatment device, a heat treatment method, and a rail steel which are suitable for preventing the occurrence of brittle fractures which originate in a base portion of a weld of the rail steel. A heat treatment device of the present invention includes a coil and heats a bottom surface of the base portion of the weld of the rail steel by induction heating. When a region in the weld which is heated to an Ac1 point or higher during welding is represented by HAZ, and the length of the HAZ in a length direction of the rail on the bottom surface of the base portion is represented by Lh, and a width of the rail steel is represented by W, the length of an outer region of the coil in the length direction of the rail is 1.2 times or more Lh and the length of the outer region of the coil in a width direction of the rail is 1.1 times or more W when viewed from opposite the bottom surface of the base portion.

Heat treatment device, heat treatment method, and rail steel

A stress-relief heat treatment method for stress-relief heat-treating a rail which is welded includes arranging at least one pair of an induction heating coil to face the rail at both sides of a welding center along the longitudinal direction of the rail while being separated from the welding center of the rail by 20 mm to 300 mm in a longitudinal direction of the rail and being an axial direction of the induction heating coil parallel to the longitudinal direction of the rail. The method further includes flowing a current to the induction heating coil arranged at one side of the welding center and to the induction heating coil arranged at the other side of the welding center being opposite to each other, and induction heating the rail to a heating temperature of 400&#xb0; C. or higher and 750&#xb0; C. or lower.

Stress-relief heat treatment apparatus

The present invention relates to a rail which has a predetermined chemical composition and satisfies expressions of 1.00&#x3c;Mn/Cr&#x2264;4.00 and 0.30&#x2264;0.25&#xd7;Mn+Cr&#x2264;1.00 and in which a structure to a depth of 25 mm from an outer surface of a head portion as the origin includes 95% or greater of a pearlite structure, the hardness of the structure is in a range of Hv 350 to 480, 50 to 500 V carbonitride having an average grain size of 5 to 20 nm are present per 1.0 &#x3bc;mof an area to be inspected in a transverse cross section at a position having a depth of 25 mm from the outer surface of the head portion, and the value obtained by subtracting the hardness of the position having the depth of 25 mm from the outer surface of the head portion from the hardness of the position having a depth of 2 mm from the outer surface of the head portion is in a range of Hv 0 to Hv 40.

A rail provided by the present invention includes: has a predetermined chemical components, wherein a value of Mn/Cr, which is a ratio of Mn content with respect to Cr content, is within a range of 0.30 to 1.00, structures in a region from a head surface constituted of a surface of a top head portion and a surface of a corner head portion to a depth of 10 mm is 98% by area or more of bainite structures, and an average hardness of the region from the head surface to a depth of 10 mm is in a range of Hv 380 to Hv 500.

A method of reheating a rail weld zone after rails were welded, a distance C between a reheating region P of a rail web portionand a welding center Q is set to more than or equal to 0.2 times and less than or equal to three times a HAZ length Lh of the rail weld zone. A length B of the reheating region P may be more than or equal to 0.5 times and less than or equal to five times the HAZ length Lh of the rail weld zone. A height A of the reheating region P may be more than or equal to 0.2 times a height Hw of the rail web portion. A temperature Th reached in a reheating process at a center of the reheating region P may be higher than or equal to 400&#xb0; C. and lower than or equal to 750&#xb0; C.

Method of reheating rail weld zone

The present invention relates to a rail which has a predetermined chemical composition and in which at least 90% of a metallographic structure from an outer surface of the rail bottom portion, as the origin, to a depth of 5 mm is a pearlite structure, a surface hardness HC of a foot-bottom central portion is in a range of Hv 360 to 500, a surface hardness HE of a foot-edge portion is in a range of Hv 260 to 315, and HC, HE, and a surface hardness HM of a middle portion positioned between the foot-bottom central portion and the foot-edge portion satisfy HC&#x2265;HM&#x2265;HE.

A rail is provided in which in a range from a surface of a head of the rail to a depth of 30 mm, 95% or more of a structure is composed of a pearlite structure by area %, and in a range with a depth of 20 mm to 30 mm from the surface of the head of the rail, an average grain size of a pearlite block in a transverse section is 120 &#x3bc;m to 200 &#x3bc;m.

An image forming apparatus includes a first conveying unit provided downstream an image forming unit; a second conveying unit provided downstream the first conveying unit; a first cutting unit provided downstream the second conveying unit; and a second cutting unit provided downstream the first cutting unit. One of the first and second cutting units cuts an upstream end of an image on the continuous sheet, the other cuts a downstream end of the same image. The second conveying unit is stopped during the cutting by the first cutting unit to form a loop of the continuous sheet, and then if the cutting is ended, the second conveying unit conveys the continuous sheet at a higher conveyance speed than a conveyance speed by the first conveying unit to reduce the loop.

Image forming apparatus and cutting device

In the rail, 95% or more of a structure in a head surface section, which is a range from surfaces of head corner sections and a head top section of the rail as a starting point to a depth of 20 mm, is a pearlite or bainite structure and the structure contains 20 to 200 MnS-based sulfides formed around an Al-based oxide as a nucleus and having a grain size in a range of 1 &#x3bc;m to 10 &#x3bc;m per square millimeter of an area to be inspected on a horizontal cross section of the rail.

A steel rail includes: by mass %, higher than 0.85% to 1.20% of C; 0.05% to 2.00% of Si; 0.05% to 0.50% of Mn; 0.05% to 0.60% of Cr; P&#x2266;0.0150%; and the balance consisting of Fe and inevitable impurities, wherein 97% or more of a head surface portion which is in a range from a surface of a head corner portion and a head top portion as a starting point to a depth of 10 mm has a pearlite structure, a Vickers hardness of the pearlite structure is Hv320 to 500, and a CMn/FMn value which is a value obtained by dividing CMn [at. %] that is a Mn concentration of a cementite phase in the pearlite structure by FMn [at. %] that is a Mn concentration of a ferrite phase is equal to or higher than 1.0 and equal to or less than 5.0.

Steel rail and method of manufacturing the same

A holder that holds a line recording head is displaced in a sheet width direction against the urging force of an elastic portion to bring an abutment portion of the holder into contact with one of a plurality of positioning surfaces provided at a reference portion of a sheet conveying mechanism. The holder is positioned and fixed to the reference portion, with the urging force exerted thereto.

Growing community of inventors

Tokyo, Japan

Masaharu Ueda