Nippon Steel & Sumitomo Metal Corporation

Toyota Jidosha Kabushiki Kaisha

Nippon Steel Corporation

Isao Anai

Hideyuki Nakamura

Takaaki Fukushi

Yasushi Yamamoto

Masaaki Kondo

Izuru Yamamoto

Satoru Shimazu

Toshio Tanoue

Katsuhiko Kato

Yoshiaki Kadoma

Yujiro Miyauchi

Takashi Motoyoshi

Itsuro Hiroshige

Hiroto Tanabe

Naoki Hori

Itsurou Hiroshige

An automobile chassis part which is excellent in low cycle fatigue characteristics, characterized by being formed by steel which contains, by mass %, C: 0.02 to 0.10%, Si: 0.05 to 1.0%, Mn: 0.3 to 2.5%, P: 0.03% or less, S: 0.01% or less, Ti: 0.005 to 0.1%, Al: 0.005 to 0.1%, N: 0.0005 to 0.006%, and B: 0.0001 to 0.01 and has a balance of Fe and unavoidable impurities, in which 80% or more of the part structure comprises a bainite structure and in which a portion where a ratio R/t of the thickness 't' and external surface curvature radius R is 5 or less has an X-ray half width of an (211) plane of 5 (deg) or less.

Automobile chassis part excellent in low cycle fatigue characteristics and method of production of same

A method of press-forming a tubular part having a cross section of an irregular shape crushes a steel tube between an upper die and a lower die in order to form a V-shaped cross section. When the curvature radius of a tip of the upper die is defined as R, the curvature radius of a bottom portion of the lower die corresponding to the tip of the upper die is defined as R, and the wall thickness of the steel tube is defined as t; R, R, and t satisfy R+2t=Rand 1.5t&#x2266;R&#x2266;3t.

Press-forming method of tubular part having cross section of irregular shape, and tubular part having cross section of irregular shape formed by the press-forming method

The present invention provides a steel material for automobile chassis parts which has high fatigue characteristics, does not require much cost for heat treatment, and further is superior in shapeability and a method of production of automobile chassis parts using this steel material, that is, one being a steel material to which Nb and Mo have been compositely added and having a difference 50 to 150 points between a Vicker's hardness of the center of plate thickness and a maximum value of Vicker's hardness within 0.5 mm from the surface after bending by a bending R of the plate outer surface of 2 to 5 times the plate thickness. The surface is high in hardness and the center part is low in hardness, so the fatigue characteristics and shapeability are superior. Note that if annealing under conditions giving a tempering parameter &#x3bb; defined by &#x3bb;=T(20+log(t)) of 14000 to 19000 (where T is the absolute temperature, t is the time (h), and the temperature rise is 660&#xb0; C.), it is possible to relieve the internal stress and further improve the fatigue characteristics.

Steel material for automobile chassis parts superior in fatigue characteristics and method of production of automobile chassis parts using the same

The present invention provides a steel material for automobile chassis parts, having high fatigue characteristics, without a heat treatment, and superior shapeability, and a method of production of such automobile chassis parts. The surface of the steel has a high hardness and the center has a low hardness, providing the superior characteristics. With an annealing step of the invention, it is possible to relieve internal stress and further improve fatigue characteristics.

Lubricative stainless steel sheet and pipe having a chromate film on at least one of the surfaces of a stainless steel sheet or pipe substrate, the chromate film having an amount of adhered Cr of 5 to 100 mg/m , and, on the chromate film, a lubricant film obtained by applying, on the chromate film, a water-base coating containing (a) a urethane resin of ether-ester type having a skeleton of bisphenol type, a skeleton of ester, and a carboxyl group, (b) an epoxy resin, and (c) a polyolefin wax, and baking the applied coating, the sum of the amount of the urethane resin of (a) and the epoxy resin of (b) being 70 to 95% by weight of the total solids of the coating, the amount of the polyolefin wax of (c) being 5 to 30% by weight of the total solids of the coating, and the lubricant film having a thickness of 0.5 to 5 micrometers and a Vickers hardness of at least 15. A method of producing a lubricative stainless steel pipe is also disclosed.

Lubricative stainless steel sheets and pipes and method of producing lubricative stainless steel pipes

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Tokyo, Japan

Isao Anai