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Heat-resistant steel for exhaust valve

A technology of heat-resistant steel and exhaust valve, which can be used in lift valves, valve devices, heat treatment furnaces, etc., and can solve the problems of poor hot workability and difficult structure control.

Active Publication Date: 2016-03-16
DAIDO STEEL CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, LV21-43 steel has problems such as difficult structure control and poor hot workability.

Method used

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  • Heat-resistant steel for exhaust valve
  • Heat-resistant steel for exhaust valve
  • Heat-resistant steel for exhaust valve

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1～34

[0114] (Examples 1-34, Comparative Examples 1-14)

[0115] [1. Production of samples]

[0116] The alloys with the compositions shown in Table 1 and Table 2 were melted in a high-frequency induction furnace to obtain a 50 kg steel ingot. The melted steel ingot was subjected to a homogenization heat treatment at 1180° C. for 16 hours, and then forged into a rod of φ18 mm. The forged material was subjected to a solution heat treatment (ST) at 1050° C.×30 minutes—oil cooling. Furthermore, 750 degreeC*4 hours-air-cooling aging treatment (AG) was performed on the material after ST.

[0117] In addition, in the comparative example 2, "Mo / C" represents "W / C". This is because W is considered to have an effect similar to that of Mo regarding solid solution strengthening.

[0118] In addition, in Comparative Examples 4 and 5, "Nb / C" represents "V / C" or "Ti / C", respectively. This is because V and Ti are considered to have effects similar to those of Nb with respect to the formation ...

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Abstract

The object of the present invention is to provide a heat-resistant steel for exhaust valves, having relatively small Ni content, high mechanical characteristics (for example, tensile strength, fatigue strength, wear resistance and hardness) at high temperature, and excellent oxidation resistance. The present invention provides a heat-resistant steel for exhaust valves, which includes: 0.45‰¤C<0.60 mass%, 0.30<N<0.50 mass%, 19.0‰¤Cr<23.0 mass%, 5.0‰¤Ni<9.0 mass%, 8.5‰¤Mn<10.0 mass%, 2.5‰¤Mo<4.0 mass%, 0.01‰¤Si<0.50 mass%, and 0.01‰¤Nb<0.30 mass%, with the balance being Fe and unavoidable impurities, in which the steel satisfies 0.02‰¤Nb / C<0.70 and satisfies 4.5‰¤Mo / C<8.9.

Description

technical field [0001] The invention relates to heat-resistant steel for exhaust valves. Background technique [0002] The engine uses an intake valve to introduce a mixture of fuel and air into the cylinder, and an exhaust valve to exhaust the combustion gas out of the cylinder. Among them, the exhaust valve is exposed to high-temperature combustion gas, so the exhaust valve uses a material with high high-temperature characteristics (such as high-temperature hardness, fatigue characteristics, high-temperature strength, wear resistance, oxidation resistance, etc.). Ni-based superalloys (for example, NCF751), austenitic heat-resistant steels (for example, SUH35) and the like are known as materials for exhaust valves. [0003] The Ni-based superalloy is a material in which the γ' phase is precipitated by aging treatment, thereby improving the strength and wear resistance at high temperatures. Ni-based superalloys are expensive, but have extremely high heat resistance. There...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00C22C38/58F01L3/02
CPCC22C38/58C21D6/004C21D9/0068C22C38/001C22C38/002C22C38/02C22C38/06C22C38/44C22C38/48C22C38/50C22C38/54F01L3/02
Inventor 大崎元嗣植田茂纪露无崇志
Owner DAIDO STEEL CO LTD
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