# US 10,371,261 B2 · Martensitic stainless-steel sheet and metal gasket

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- Number: US 10,371,261 B2
- Document ID: US10371261B2
- Status: Granted
- Kind: B2
- Application number: 15/305,108
- Filed: 2015-03-16
- Published: 2017-04-27
- Granted: 2019-08-06
- Earliest claimed: 2014-05-02
- Assignees: Nippon Steel Nisshin Co., Ltd.
- Applicants: Nippon Steel Nisshin Co., Ltd.
- Inventors: Hiroyasu Matsubayashi; Sadayuki Nakamura; Junichi Katsuki; Ryoji Hirota
- Web page: https://patentgrep.com/patent/US10371261B2

## CPC

- C21D 9/48: deep-drawing sheets
- F16J 15/0806: {characterised by material or surface treatment}
- C21D 6/004: {containing Cr and Ni}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 8/0226: {Hot rolling}
- C21D 8/0236: {Cold rolling}
- C21D 8/0263: {following hot rolling}
- C21D 8/0273: {Final recrystallisation annealing}
- C21D 8/0278: involving a particular surface treatment (C21D8/0294 takes precedence)
- C21D 8/0426: {Hot rolling}
- C21D 8/0436: {Cold rolling}
- C21D 8/0447: {characterised by the heat treatment}
- C21D 9/02: for springs
- C21D 9/46: for sheet metals
- C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00)
- C22C 38/001: {containing N}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/46: with vanadium
- C22C 38/48: with niobium or tantalum
- C22C 38/50: with titanium or zirconium
- C22C 38/54: with boron
- C22C 38/58: with more than 1.5% by weight of manganese
- C23G 1/02: with acid solutions
- F16J 15/08: with exclusively metal packing
- F16J 15/0818: {Flat gaskets}
- C21C 7/06: Deoxidising, e.g. killing
- C21D 2211/004: Dispersions; Precipitations
- C21D 2211/005: Ferrite
- C21D 2211/008: Martensite
- F16J 2015/085: {without fold over}
- F16J 2015/0868: {Aspects not related to the edges of the gasket}
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C21C: PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

## Abstract

Provided is a martensitic stainless-steel sheet having a reduced anisotropy in workability and fatigue resistance which are attributable to oxide based inclusions. A martensitic stainless-steel sheet which has a steel composition that contains, in terms of mass %, 0.030 to 0.300% C, 0.20 to 2.50% Si, 0.15 to 4.00% Mn, 0.01 to 1.00% Ni, 11.00 to 15.00% Cr, 0.001 to 0.100% N, 0.0001 to 0.0350% Al, 0 to 0.50% V, 0 to 0.50% Nb, 0 to 0.50% Ti, 0 to 0.020% B, and a balance of Fe and unavoidable impurities, and that has a value of γmax, determined by the following equation (1), of 80.0 or greater, and in which oxide based inclusions are observed in the metallographic structure, the oxide based inclusions having a converted composition comprising up to 30 mass % or less Al2O3, 20 to 60 mass % SiO2, and 15 to 70 mass % MnO.

## Claims

### Claim 1

A martensitic stainless cold-rolled and annealed steel sheet having a sheet thickness of 0.05 mm to 0.5 mm and having a steel composition that comprises, in terms of mass %, 0.030 to 0.300% C, 0.20 to 2.50% Si, 0.15 to 4.00% Mn, 0.01 to 1.00% Ni, 11.00 to 15.00% Cr, 0.001 to 0.100% N, 0.0001 to 0.0350% Al, 0 to 0.50% V, 0 to 0.50% Nb, 0 to 0.50% Ti, 0 to 0.020% B, and a balance of Fe and inevitable impurities, and that has a value of γmax, which is determined by a following equation (1), of 80.0 or greater, and in which an average composition of oxide based inclusions observed in a metailographic structure has 30 mass % or less Al2O3, 20 to 60 mass % SiO2 and 15 to 70 mass % MnO in terms of mass ratio conversion of Al2O3, SiO2 and MnO, and maximum diameters of the oxide based inclusions in the sheet thickness direction are 1.0% or less of the sheet thickness:
γmax=420C−11.5Si+7Mn+23Ni−11.5Cr−49(Ti+Nb +V)−52Al+470N+189 (1)
herein, a place of the element symbol in the equation (1) is assigned with a content of the corresponding element denoted in terms of mass %.

### Claim 2 (depends on 1)

The martensitic stainless cold-rolled and annealed steel sheet according to claim 1, wherein in the steel composition, any one of following equations (A) and (B) is satisfied:
Si+Mn≥1.30 and 0.25≤Si/Mn≤1.50 (A)
Si+Mn<1.30 and 0.40≤Si/Mn≤1.50 (B)
herein, places of Si and Mn in the equations (A) and (B) are assigned with contents of Si and Mn denoted in terms of mass %.

### Claim 3 (depends on 1)

The martensitic stainless cold-rolled and annealed steel sheet according to claim 1 and having sheet surface (rolling surface) hardness of 400 HV to 470 HV.

### Claim 4 (depends on 1)

A metal gasket manufactured by forming a cold-rolled and annealed steel sheet according to claim 1,
the metal gasket comprising a bead formed by press forming,
wherein the metal gasket is to be used with a bead apex being pressed to a contact party material.

### Claim 5

A martensitic stainless cold-rolled and annealed steel sheet having a steel composition that comprises, in terms of mass %, 0.030 to 0.300% C, 0.20 to 2.50% Si, 0.15 to 4.00% Mn, 0.01 to 1.00% Ni, 11.00 to 15.00% Cr, 0.001 to 0.100% N, 0.0001 to 0.0350% Al, 0 to 0.50% V, 0 to 0.50% Nb, 0 to 0.50% Ti, 0 to 0.020% B, and a balance of Fe and inevitable impurities, and that has a value of γmax, which is determined by a following equation (1), of 80.0 or greater, and in which an average composition of oxide based inclusions observed in a metallographic structure has 30 mass % or less Al2O3, 20 to 60 mass % SiO2 and 15 to 70 mass % MnO in terms of mass ratio conversion of Al2O3, SiO2 and MnO and having a surface in which a number density of pits having an opening diameter of 1.0 μm or greater, which are formed as precipitated particles are detached in an acid pickling treatment after finish annealing, is 10 pits/0.01 mm2 or greater and a surface roughness Ra in a rolling-perpendicular direction is 0.500 μm or less:
γmax=420C−11.5Si+7Mn+23Ni−11.5Cr−49(Ti+Nb+V)−52Al+470N+189 (1)
herein, a place of the element symbol in the equation (1) is assigned with a content of the corresponding element denoted in terms of mass %.

### Claim 6 (depends on 5)

The martensitic stainless cold-rolled and annealed steel sheet according to claim 5, wherein the precipitated particles are carbide particles.

### Claim 7 (depends on 5)

A metal gasket manufactured by forming a cold-rolled and annealed steel sheet according to claim 5,
the metal gasket comprising a bead formed by press forming,
wherein the metal gasket is to be used with a bead apex being pressed to a contact party material.