Metal gasket and a material for its manufacture and a method for their manufacture
A metal gasket, stainless steel technology, applied in the field of stainless steel, can solve the problems of height reduction, flange crushing, heavy, etc., and achieve the effect of suppressing the formation of defects and good fatigue performance
Inactive Publication Date: 2004-08-18
NIPPON STEEL CORP +1
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- Description
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- Application Information
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Problems solved by technology
Therefore, when the gasket is placed between the cylinder head and the cylinder block and sandwiched by screws etc., there is a problem that a permanent strain occurs in which the flange is crushed and its height is lowered
Heat treatment at such a high temperature is a heavy burden for gasket processors, and the process of processing gaskets becomes complicated due to the addition of precipitation strengthening heat treatment steps
Therefore, in the past, it was difficult to practically utilize metal shims whose strength was increased by using precipitation strengthening
Another problem with prolonged heat treatment at high temperature for precipitation strengthening is that it tends to cause the formation of rough precipitates, which are the starting point for fatigue cracking
Method used
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[0078] Stainless steels having the compositions shown in Table 1 were melted and hot-rolled in a vacuum melting furnace, and annealing and cold-rolling were repeated. The obtained cold-rolled steel is subjected to final annealing at a temperature of 700-1100° C. and a heating time of 1-600 seconds, and then hardened cold-rolled. The sheet thickness (t) after temper rolling was 0.2 mm in each case. The hardened cold-rolled steel sheet is cut into 170×170mm, and the obtained test piece is stamped with a predetermined die to form a flange with a cross-sectional shape shown in the plan view and perspective view of Figure 3(a) and 3(b), with a ring diameter of about 60mm, and finally aged at 300°C for 1 minute.
[0079] In addition, one test piece was taken out of the stainless steel piece after each step of finish annealing, temper rolling, and aging, and the following investigation was carried out.
[0080] For the microstructure, the average particle diameter of the recrystall...
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Abstract
This invention relates to a stainless steel gasket having markedly improved strength and fatigue properties due to precipitation strengthening. Its composition comprises C: at most 0.03%, Si: at most 1.0%, Mn: at most 2%, Cr: 16.0% - 18.0%, Ni: 6.0% - 8.0%, N: at most 0.25%, if necessary Nb: at most 0.30%, and a remainder of Fe and unavoidable impurities. After cold rolling, final annealing is carried out, and after a structure is formed of recrystallized grains with an average grain diameter of at most 5 mu m having an area ratio of 50 - 100% and an unrecrystallized portion having an area ratio of 0 - 50%, a metal gasket is formed by steps including temper rolling with a reduction of at least 30% to make the area ratio of a strain induced martensite phase at least 40%, and forming and heat treatment at 200 - 350 DEG C. The metal gasket has a duplex phase structure of at least 40% martensite in which chromium nitride is precipitated and a remainder of austenite, or it has a single phase structure of martensite in which chromium nitride is precipitated, and it has Hv of at least 500.
Description
technical field [0001] The present invention relates to a metal gasket, especially a metal gasket for an engine of an automobile or a motorcycle, etc., and a stainless steel for processing the metal gasket, and a method for their production. [0002] Hereinafter, the present invention will be explained particularly by taking a metal gasket for an engine as an example, but the metal gasket of the present invention is not limited thereto. Background technique [0003] An engine gasket called a head gasket is a sealing element placed between the cylinder head and the cylinder block that stops the leakage of combustion gases or engine cooling water or oil. [0004] In the past, as a cover gasket, a composite type gasket was used, which has a structure in which a compression element is wound in mild steel, but now, almost all gaskets are metal gaskets that substantially contain metal sheets. [0005] A metal gasket (cap gasket) for an engine has the same shape as a gasket sealin...
Claims
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IPC IPC(8): C21D8/02C22C38/00C22C38/02C22C38/04C22C38/48C22C38/58
CPCC22C38/04C21D8/0205C21D2211/008C22C38/48C21D8/0273C22C38/02C21D8/0236Y10S148/908C21D2211/004C22C38/58C22C38/001Y10T428/31707
Inventor 安达和彦石山成志御所洼贤一桂井隆
Owner NIPPON STEEL CORP