Jfe Steel Corporation

Kawasaki Steel Corporation

Junichiro Hirasawa

Osamu Furukimi

Takumi Ujiro

Atsushi Miyazaki

Mineo Muraki

Susumu Satoh

Yoshihiro Yazawa

Naoto Yoshimi

Hideyuki Takahashi

Shin Ishikawa

Kohei Hasegawa

Chikara Kami

Shinji Ootsuka

Hideki Nagano

Yoshitsugu Suzuki

Hiroki Ota

Yoichi Makimizu

Hiroki Nakamaru

Takayoshi Yano

Masato Sasaki

Kazuhide Ishii

Yoshihiro Ozaki

Mai Miyata

Shinji Otsuka

Haruhiko Ishizuka

Hideyuki Tsurumaru

Keita Yonetsu

Stainless steel sheets including a Ni and O-containing coating on the surface that has excellent weld penetration characteristics and excellent crevice corrosion resistance, and a method for producing such stainless steel sheets. A stainless steel sheet includes a Ni and O-containing coating on a surface of the stainless steel sheet. The Ni and O-containing coating has a coating weight of greater than or equal to 0.1 g/mand less than or equal to 20 g/m. The Ni and O-containing coating has a composition including, in at. %, Ni: greater than or equal to 25% and less than or equal to 60%, and O: greater than or equal to 40% and less than or equal to 70%.

Stainless steel sheet including Ni and O-containing coating on surface and method for producing stainless steel sheet

The ferritic stainless steel sheet contains, in mass%, C: 0.020% or less, Si: 0.6% or less, Mn: 0.5% or less, P: 0.04% or less, S: 0.010% or less, Al: 0.015% or more and 0.20% or less, Cr: 17.0% or more and 24.0% or less, Ni: less than 0.6%, N: 0.020% or less, Ca: 0.0002% or more and 0.0020% or less, and O: 0.0050% or less and further contains one or two selected from Ti: 0.01% or more and 0.45% or less and Nb: 0.01% or more and 0.55% or less, with the balance being Fe and unavoidable impurities. The ferritic stainless steel sheet satisfies (Ti+Nb&#xd7;48/93)/(C+N)&#x2265;8.0 (where Ti, Nb, C, and N represent the contents (% by mass) of these elements, respectively).

Ferritic stainless steel sheet for plasma arc welding and welding method therefor

A high-strength cold-rolled steel sheet having high chemical convertibility and a tensile strength of 590 MPa or more and a method for producing such a steel sheet are provided. The steel sheet contains, in terms of percent by mass, C: 0.05 to 0.3%, Si: 0.6 to 3.0%, Mn: 1.0 to 3.0%, P: 0.1% or less, S: 0.05% or less, Al: 0.01 to 1%, N: 0.01% or less, and the balance being Fe and unavoidable impurities. The coverage ratio of reduced iron on a steel sheet surface is 40% or more. In order to produce such a steel sheet, an oxidation treatment is performed after cold rolling. Subsequently, annealing is conducted in a furnace in a 1 to 10 vol % H+balance Ngas atmosphere with a dew point of &#x2212;25&#xb0; C. or less.

High-strength cold-rolled steel sheet and method for producing the same

A method for manufacturing high-Si cold rolled steel sheets includes heating a cold rolled steel sheet with a direct flame burner (A) having an air ratio of not more than 0.89 when the temperature of the cold rolled steel sheet that is being increased is in the temperature range of not less than 300&#xb0; C. and less than Ta&#xb0; C., subsequently heating the cold rolled steel sheet with a direct flame burner (B) having an air ratio of not less than 0.95 when the temperature of the cold rolled steel sheet is in the temperature range of not less than Ta&#xb0; C. and less than Tb&#xb0; C., and subsequently soak-annealing the cold rolled steel sheet in a furnace having an atmospheric gas composition which has a dew point of not more than &#x2212;25&#xb0; C. and contains 1 to 10 volume % of Hand the balance of N.

Method for manufacturing high-Si cold rolled steel sheet having excellent chemical conversion properties

A stainless steel sheet with excellent heat and corrosion resistances for a brake disk is provided. Specifically, in mass %, C: less than 0.10%, Si: 1.0% or less, Mn: 1.0 to 2.5%, P: 0.04% or less, S: 0.01% or less, Cr: more than 11.5% but not more than 15.0%, Ni: 0.1 to 1.0%, Al: 0.10% or less, Nb: more than 0.08% but not more than 0.6%, V: 0.02 to 0.3%, and N: more than 0.03% but not more than 0.10% are contained so that 0.03&#x2266;{C+N&#x2212;(13/93)Nb}&#x2266;0.10, (5Cr+10Si+15Mo+30Nb+50V&#x2212;9Ni&#x2212;5Mn&#x2212;3Cu&#x2212;225N&#x2212;270C)&#x2266;45, and {(14/50)V+(14/90)Nb}&#x3c;N (wherein Cr, Si, Mo, Nb, Ni, Mn, Cu, V, N, and C represent the contents (mass %) of the corresponding elements) are satisfied. With such a composition, the stainless steel sheet for a brake disk can be provided with both excellent heat resistance and excellent corrosion resistance after tempering.

Stainless steel sheet with excellent heat and corrosion resistances for brake disk

A method for the manufacturing of high strength cold rolled steel sheets includes continuously annealing a cold rolled steel sheet that has a composition containing C: 0.05-0.3% mass, Si: 0.6-3.0% mass, Mn: 1.0-3.0% mass, P: &#x2266;0.1% mass, S: &#x2266;0.02% mass, Al: 0.01-1% mass, N: &#x2266;0.01% mass, and Fe and inevitable impurities: balance, in a manner such that the cold rolled steel sheet is heated in a furnace using an oxidizing burner to a steel sheet temperature of &#x2267;700&#xb0; C., then soak-annealed in a reducing atmosphere furnace at 750-900&#xb0; C., then cooled so the average cooling rate between 500&#xb0; C. and 100&#xb0; C. is &#x2267;50&#xb0; C./s. High-Si cold rolled steel sheets with high strength and good phosphatability while containing Si&#x2267;0.6% are obtained without controlling conditions so as to increase the dew point in the reducing atmosphere in the soaking furnace or to increase the vapor hydrogen partial pressure ratio.

Method for manufacturing of high strength cold rolled steel sheet of excellent phosphatability

A brake disk excellent in temper softening resistance and toughness comprising, by mass, 0.1% or less of C, 1.0% or less of Si, 2.0% or less of Mn, 10.5% to 15.0% of Cr, and 0.1% or less of N, the remainder being Fe and unavoidable impurities, such that the following inequalities are satisfied: 5Cr+10Si+15Mo+30Nb&#x2212;9Ni&#x2212;5Mn&#x2212;3Cu&#x2212;225N&#x2212;270C&#x3c;45 (1) and 0.03&#x2266;{C+N&#x2212;(13/92)Nb}&#x2266;0.09 (2) wherein Cr, Si, Mo, Nb, Ni, Mn, Cu, N, and C each represent the content of the corresponding elements on a mass percent basis, and having a martensitic structure having prior-austenite grains with an average diameter of 8 to less than 15 &#x3bc;m.

Brake disk excellent in temper softening resistance and toughness

The soft Cr-containing steel includes, on a % by mass basis, C: from about 0.001% to about 0.020%, Si: more than about 0.10% and less than about 0.50%, Mn: less than about 2.00%, P: less than about 0.060%, S: less than about 0.008%, Cr: from about 12.0% to about 16.0%, Ni: from about 0.05% to about 1.00%, N: less than about 0.020%, Nb: from about 10&#xd7;(C+N) to about 1.00%, Mo: more than about 0.80% and less than about 3.00%, wherein the contents of alloying elements, represented by Si and Mo, respectively, on a % by mass, satisfy the formula Si&#x2266;1.2-0.4 Mo, so as to prevent precipitation of the Laves phase and to stably secure an effect of increasing high-temperature strength due to solid solution Mo.

Soft Cr-containing steel

A martensitic stainless steel, having high temper softening resistance, for disc brakes is provided. The martensitic stainless steel is not seriously softened by maintaining the steel at more than 600&#xb0; C. The steel has a hardness of 32 or more or a hardness of 30 or more in HRC after the steel is tempered at 650&#xb0; C. for one hour or tempered at 670&#xb0; C. for one hour, respectively. In particular, the martensitic stainless steel for disc brakes contains less than 0.050 mass % carbon, 1.0 mass % or less silicon, 2.0 mass % or less manganese, 0.04 mass % or less phosphorus, 0.010 mass % or less sulfur, 0.2 mass % or less aluminum, more than 11.5 mass % to 15.0 mass % chromium, 0.5 mass % to 2.0 mass % nickel, more than 0.50 mass % to 4.0 mass %. copper, more than 0.08 mass % to 0.6 mass % niobium, and less than 0.09 mass % nitrogen, the remainder being iron and unavoidable impurities. The carbon content, the nitrogen content, the niobium content, the chromium content, the silicon content, the nickel content, the manganese content, and the copper content satisfy the following inequalities (1) and (2):0.03&#x2266;[C]+[N]&#x2212;13/93&#xd7;[Nb]&#x2266;0.09 &#x2003;&#x2003;(1)5&#xd7;[Cr]+10&#xd7;[Si]+30&#xd7;[Nb]&#x2212;9&#xd7;[Ni]&#x2212;5&#xd7;[Mn]&#x2212;3&#xd7;[Cu]&#x2212;225&#xd7;[N]&#x2212;270&#xd7;[C]&#x2266;40 &#x2003;&#x2003;(2).

Martensitic stainless steel for disk brakes

A martensitic stainless steel sheet having superior corrosion resistance, toughness at the weld zones, and workability. The composition of the steel sheet is, on a mass basis: less than about 0.02% of carbon; about 1.0% or less of silicon; less than about 1.5% of manganese; about 0.04% or less of phosphorus; about 0.01% or less of sulfur; about 0.1% or less of aluminum; about 1.5% or more and less than about 4.0% of nickel; about 11% or more and less than about 15% of chromium; about 0.5% or more and less than about 2.0% of molybdenum; and less than about 0.02% of nitrogen, the balance being iron and unavoidable impurities, wherein 15.0%&#x2266;[Cr]+1.5&#xd7;[Mo]+1.2&#xd7;[Ni]&#x2266;20.0%; [C]+[N]&#x3c;0.030%; [Ni]+0.5&#xd7;([Mn]+[Mo])+30&#xd7;[C]&#x3e;3.0%; and 8.0%&#x2266;72&#xd7;[C]+40&#xd7;[N]+3&#xd7;[Si]+2&#xd7;[Mn]+4&#xd7;[Ni]+[Mo]&#x2266;18.0%.

Martensitic stainless steel sheet and method for making the same

A structural hot-rolled or cold-rolled stainless steel sheet having improved intergranular corrosion resistance and toughness at the welding heat affected zone and further having low strength and high elongation. The composition of the steel sheet contains less than about 0.008 mass percent of C; about 1.0 mass percent or less of Si; about 1.5 mass percent or less of Mn; about 11 to about 15 mass percent of Cr; more than about 1.0 mass percent and about 2.5 mass percent or less of Ni; less than about 0.10 mass percent of Al; about 0.009 mass percent or less of N; about 0.04 mass percent or less of P; about 0.01 mass percent or less of S; and the balance being Fe and incidental impurities. These contents satisfy the expressions: (Cr)+1.2&#xd7;(Ni)&#x2267;15.0; (Ni)+0.5&#xd7;(Mn)+30&#xd7;(C)&#x2266;3.0; (C)+(N)&#x2266;0.015; and (Cr)&#x2212;(Mn)&#x2212;1.7&#xd7;(Ni)&#x2212;27&#xd7;(C)&#x2212;100&#xd7;(N)&#x2267;9.0.

Stainless steel sheet for welded structural components and method for making the same

The soft Cr-containing steel includes, on a % by mass basis, C: from about 0.001% to about 0.020%, Si: more than about 0.10% and less than about 0.50%, Mn: less than about 2.00%, P: less than about 0.060%, S: less than about 0.008%, Cr: from about 12.0% to about 16.0%, Ni: from about 0.05% to about 1.00%, N: less than about 0.020%, Nb: from about 10&#xd7;(C+N) to about 1.00%, Mo: more than about 0.80% and less than about 3.00%, wherein the contents of alloying elements, represented by Si and Mo, respectively, on a % by mass, satisfy the formula Si&#x2266;1.2&#x2212;0.4Mo, so as to prevent precipitation of the Laves phase and to stably secure an effect of increasing high-temperature strength due to solid solution Mo.

Material for stainless steel sheets is heated to a temperature within a range of 850 to 1250&#xb0; C. and cooled at a rate 1&#xb0; C./s or faster, the material including 0.02% by mass or less of C, 1.0% by mass or less of Si, 2.0% by mass or less of Mn, 0.04% by mass or less of P, 0.01% by mass or less of S, 0.1% by mass or less of Al, 11% by mass or more but less than 17% by mass of Cr, 0.5% by mass or more but, less than 3.0% by mass of Ni, and 0.02% by mass or less of N, so as to satisfy specific relationships between the compositions.

High-strength stainless steel material in the form of a wheel rim and method for manufacturing the same

The soft Cr-containing steel includes, on a % by mass basis, C: from about 0.001% to about 0.020%, Si: more than about 0.10% and less than about 0.50%, Mn: less than about 2.00%, P: less than about 0.060%, S: less than about 0.008%, Cr: from about 12.0% to about 16.0%, Ni: from about 0.05% to about 1.00%, N: less than about 0.020%, Nb: from about 10&times;(C&plus;N) to about 1.00%, Mo: more than about 0.80% and less than about 3.00%, wherein the contents of alloying elements, represented by Si and Mo, respectively, on a % by mass, satisfy the formula Si &lE;1.2&minus;0.4 Mo, so as to prevent precipitation of the Laves phase and to stably secure an effect of increasing high-temperature strength due to solid solution Mo.

A corrosion-resistant chromium steel for architectural and civil engineering structural elements, includes 0.0015 to 0.02 mass percent C, 0.0015 to 0.02 mass percent N, 0.1 to 1.0 mass percent Si, 0.1 to 3.0 mass percent Mn, more than 5 mass percent to less than 10 mass percent Cr, 0.01 to 3.0 mass percent Ni, 0.1 mass percent or less of Al, 0.05 mass percent or less of P, 0.03 mass percent or less of S, 0.01 to 1.0 mass percent Co, and the balance being Fe and incidental impurities. The steel has high long-term corrosion resistance and high weld-zone toughness. Preferably, the steel further includes 0.01 to 0.5 mass percent V and 0.001 to 0.05 mass percent W, the Cr content is in the range of more than 5 mass percent to less than 8 mass percent, and the Cr, V, and W contents are within a specified ratio.

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Chiba, Japan

Junichiro Hirasawa