Heat resisting cast iron and exhaust system part therefrom

一种耐热铸铁、排气系统的技术，应用在排气装置、发动机元件、机械设备等方向，能够解决常温拉伸降低、韧性及延展性降低、无法确保耐久性等问题，达到性能提高、耐氧化性及耐热裂纹性优异的效果

Active Publication Date: 2007-03-07
PROTERIAL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0020] However, if the spheroidal graphite cast iron of JP-A-11-71628 is used in exhaust system parts used in an environment exceeding 800°C, the pearlite phase, bainite phase, and martensite phase will decompose, and secondary graphite will precipitate. Durability cannot be ensured due to irreversible expansion
In addition, among Mo, Cu, Cr, V, W, Sn, and Sb, V deteriorates the oxidation resistance at a temperature exceeding 800°C, and if Sn and Sb become excessive, there will be scales at the boundary of the eutectic group Shaped abnormal graphite is formed, and cementite is formed in the substrate structure, resulting in a decrease in toughness and ductility, especially a decrease in room temperature elongation.
Therefore, if the alloying elements and their contents cannot be appropriately selected from among Mo, Cu, Cr, V, W, Sn, and Sb, then as materials for exhaust system parts used in an environment exceeding 800°C, it is difficult to Cannot ensure sufficient Ac 1 Phase transition point, oxidation resistance, heat crack resistance, toughness and ductility
Therefore, from the composite roll described in JP-A-11-71628, no heat-resistant cast iron suitable for exhaust system parts used in an environment exceeding 800°C can be conceived.

Method used

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  • Heat resisting cast iron and exhaust system part therefrom
  • Heat resisting cast iron and exhaust system part therefrom
  • Heat resisting cast iron and exhaust system part therefrom

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1～74

[0135] Embodiments 1-74, comparative examples 1-16, existing examples 1-6

[0136] with SiO 2Cast iron having the chemical composition (weight%) shown in Table 1 was melted in the atmosphere of a 100kg high-frequency furnace for lining, and the iron was tapped at 1450°C or higher, and the process was carried out according to the sandwich method using commercially available Fe-Si-Mg. Spheroidization. Immediately thereafter, it is cast into the Y mold at 1300°C or higher. After demoulding, each sample was subjected to shot blasting, and as shown in Table 2, after being kept at a temperature of 600 to 940° C. for 3 hours, furnace-cooled ferritizing annealing was performed. In addition, the test materials of Example 9, Comparative Examples 1 and 9, and Conventional Examples 1, 2 and 4 were not heat-treated, and the test materials of Comparative Example 2 were subjected to ferrite cooling by air cooling instead of furnace cooling. annealing. The samples of Conventional Examples...

Embodiment 75

[0231] Using the heat-resistant cast iron of Example 9, the exhaust manifold 151 shown schematically in FIG. 17 was cast, and then machined directly in the cast state. The obtained exhaust manifold 151 had no casting defects such as pores, stagnation, and gas defects, and no problems such as cutting inconvenience occurred during machining. Also in Fig. 17, 151a denotes a mounting flange, 151b denotes a branch pipe, and 151c denotes a gathering portion.

[0232] The exhaust manifold 151 of Example 75 was assembled on an exhaust simulator (simulator) simulating a high-performance gasoline engine (gasoline engine) with a displacement of 2000 cc with inline 4 cylinders, and the durability test was carried out to investigate the life and cracks until cracks occurred. Occurs. As test conditions, a heating-cooling cycle consisting of heating for 10 minutes and cooling for 10 minutes was repeated, and the number of cycles until cracks penetrating the exhaust manifold 151 occurred was...

Embodiment 76

[0235] Exhaust manifold 151 was manufactured from the heat-resistant cast iron of Example 8 in the same manner as in Example 75 except that it was held at 900° C. for 3 hours and then subjected to furnace-cooled ferritization annealing. The obtained exhaust manifold 151 had no casting defects, and no problems such as deformation due to heat treatment and problems in machining. The exhaust manifold 151 of Example 76 was assembled in an exhaust simulator, and an endurance test was carried out under the same conditions as in Example 75. The surface temperature of the exhaust manifold 151 is the same as that of Example 75. As a result of the durability test, in the exhaust manifold 151 of Example 76, minute cracks of the same degree occurred at the same position as that of Example 75 after 952 cycles. However, no cracks occurred in the collection part where the high-temperature exhaust gas passes, and the entire part was hardly oxidized, and it was confirmed that it has excellent...

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Abstract

A heat resisting cast iron containing graphite for use in exhaust system parts used at temperatures exceeding 800 DEG C, which heat resisting cast iron comprises, on weight basis, 3.5 to 5.6% of Si and 1.2 to 15% of W, having an interlayer with W and Si concentrated therein on boundaries of graphite and the base structure. Exhaust system parts comprised of this heat resisting cast iron have an AC1 transformation point, as measured while raising temperature from 30 DEG C at a rate of 3 DEG C / min, of 840 DEG C or higher and exhibit a thermal crack life of 780 cycles or more at a thermal fatigue test in which heating and cooling are performed under such conditions that the upper limit temperature is 840 DEG C, the temperature amplitude 690 DEG C and the constraint ratio 0.25.

Description

technical field [0001] The present invention relates to a heat-resistant cast iron having high oxidation resistance and heat crack resistance, and particularly relates to exhaust manifolds, turbocharger housings, catalyst cases, etc. suitable for automotive engines Heat-resistant cast iron for exhaust system parts. Background technique [0002] Exhaust manifolds, turbocharger housings, catalyst cases, turbocharger housing-integrated exhaust manifolds, catalyst case-integrated exhaust manifolds, exhaust outlets, etc. for motor vehicle engines Exhaust system parts are required to be improved in oxidation resistance and corrosion resistance because they are repeatedly exposed to high-temperature exhaust gas from the engine and are used under severe conditions such as sulfur oxides and nitrogen oxides directly exposed to exhaust gas. Heat resistance such as thermal crack resistance to ensure high durability and long life. For this reason, exhaust system parts have been formed ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C37/00F01N13/16
CPCC22C37/10C21D5/00C22C37/04F01N13/16C22C33/08C22C37/00
Inventor 五十岚芳夫远藤诚一三宅正浩川田常宏
Owner PROTERIAL LTD
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