Austenitic cast iron and manufacturing process for the same, austenitic-cast-iron cast product and component part for exhaust system
a technology which is applied in the field manufacturing process, austenitic cast iron product and component part of the exhaust system, can solve the problems of reducing the elongation of austenitic cast iron, not being practicable to enhance oxidation, and worsening the machinability, so as to improve the high-temperature proof stress of cast iron and improve the oxidation resistance. , the effect of improving
Inactive Publication Date: 2010-11-11
TOYOTA IND CORP +1
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Benefits of technology
The present invention provides a low-cost austenitic cast iron that is excellent in terms of thermal-fatigue strength and oxidation resistance. By adjusting the content of carbon, silicon, chromium, nickel, manganese, and copper in the cast iron, the invention achieves good oxidation resistance without increasing the silicon content excessively. The invention also provides a manufacturing process for the cast iron and some applications of the cast iron. The technical effects of the invention include improved thermal-fatigue strength and oxidation resistance in low-cost austenitic cast irons.
Problems solved by technology
However, according to studies by the present inventors, the Si content that becomes excessive results in declining the elongation of austenitic cast iron, and in worsening the machinability.
Consequently, considering the reliability and the mass-producibility of heat-resistant members comprising austenitic cast irons, and the like, it is not practical to enhance the oxidation resistance to such a level that is sufficient in view of practical use by only adjusting the Si content.
Method used
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[0201]The present invention will be explained more concretely while giving examples.
[0202](First Test)
[0203](1) Manufacturing Method of Test Specimens
[0204]Raw materials, which included at least one or more members of C, Si, Cr, Ni, Mn and Cu (i.e., basic elements) and the balance of Fe, were blended and mixed variously, and they were air melted with a high-frequency furnace, thereby obtaining 47-kg molten metals (i.e. , a molten-metal preparation step). Each of these molten metals was poured into a casting die (e.g., sand die) that had been made ready in advance (i.e., a pouring step). On this occasion, they were tapped at about 1,550° C., and were poured at about 1,450° C. Moreover, the after-pouring molten metals were solidified by natural cooling (that is, in a state of as cast), thereby obtaining test specimens with said configuration (or cast products) (i.e., a solidification step).
[0205]Note that the addition of an auxiliary agent, such as an inoculant agent and spheroidizing...
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Abstract
An austenitic cast iron according to the present invention has Ni: from 7 to 15% by mass, and is characterized in that it comprises a base structure in which an austenite phase makes a major phase even in ordinary-temperature region by adjusting the respective compositions of Cr, Ni and Cu, excepting C and Si, so as to fall within predetermined ranges. In accordance with the present invention, it is possible to obtain an austenitic cast iron, which is excellent in terms of oxidation resistance and the like, inexpensively, while reducing the content of expensive Ni.
Description
TECHNICAL FIELD[0001]The present invention relates to an austenitic cast iron, which is excellent in terms of heat resistance, and the like; to a cast product, which is comprised of that; to a production process for the same; and to a component part for exhaust system.BACKGROUND ART[0002]It is often the case that members being formed as complicated configurations, and relatively large-size members are manufactured bymeans of casting; what is more cast products being made of relatively inexpensive cast irons (hereinafter referred to as “cast products” simply) are used frequently.[0003]In cast iron, C in the alloy whose major component is made of iron-carbon exceeds the maximum solid solubility limit in γ iron (e.g., about 2% by mass), and the cast iron is accompanied by eutectoid solidification. Usually, in order to improve the characteristics, such as the mechanical properties, corrosion resistance and heat resistance, various alloying elements are added. Such a cast alloy is referr...
Claims
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IPC IPC(8): C22C37/08C22C37/00C22C38/42C22C38/16C22C38/40C22C38/08C22C37/06C22C37/10B22D27/00
CPCC21C1/105C22C37/08C22C37/04
Inventor SUGIYAMA, TOMOHEIISHIKAWA, MANABUISOMURA, HIROYUKIKOJIMA, MAMORUYAMAMOTO, NAOKIKINOSHITA, KYOICHIFUJIKAWA, TAKAO
Owner TOYOTA IND CORP