Heat-resisting steel for exhaust valves

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: 2014-04-30
DAIDO STEEL CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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-resisting steel for exhaust valves
  • Heat-resisting steel for exhaust valves
  • Heat-resisting steel for exhaust valves

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1～34

[0114] (Examples 1 to 34, Comparative Examples 1 to 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 smelted steel ingot was subjected to homogenization heat treatment at 1180°C for 16 hours, and then forged into a φ18 mm bar. The forged material is subjected to a solution heat treatment (ST) of 1050°C×30 minutes-oil cooling. Furthermore, the material after ST was subjected to aging treatment (AG) of 750° C.×4 hours-air cooling.

[0117] It should be noted that in Comparative Example 2, "Mo / C" means "W / C". This is because W is considered to have an effect similar to Mo in terms of solid solution strengthening.

[0118] In addition, in Comparative Examples 4 and 5, "Nb / C" means "V / C" or "Ti / C", respectively. This is because with regard to the formation of carbonitrides, it is considered that V and Ti respectively have effects similar to ...

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Abstract

The purpose of the present invention is to provide a heat-resisting steel for exhaust valves, which contains a relatively small amount of Ni and has excellent mechanical characteristics (such as tensile strength, fatigue strength, wear resistance and hardness) at high temperatures and excellent corrosion resistance. The present invention provides a heat-resisting steel for exhaust valves, which contains 0.45 mass% or more but less than 0.60 mass% of C, 0.30-0.50 mass% (exclusive) of N, 19.0 mass% or more but less than 23.0 mass% of Cr, 5.0 mass% or more but less than 9.0 mass% of Ni, 8.5 mass% or more but less than 10.0 mass% of Mn, 2.5 mass% or more but less than 4.0 mass% of Mo, 0.01 mass% or more but less than 0.50 mass% of Si and 0.01 mass% or more but less than 0.30 mass% of Nb, with the balance made up of Fe and unavoidable impurities. This heat-resisting steel for exhaust valves satisfies 0.02 <= Nb/C < 0.70 and 4.5 <= Mo/C < 8.9.

Description

Technical field [0001] The present invention relates to heat-resistant steel for exhaust valves. Background technique [0002] The engine uses an intake valve for introducing a mixed gas of fuel and air into the cylinder, and an exhaust valve for discharging the combustion gas out of the cylinder. Among them, since the exhaust valve is exposed to high-temperature combustion gas, 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.). As materials for exhaust valves, Ni-based superalloys (for example, NCF751), austenitic heat-resistant steels (for example, SUH35), and the like are known. [0003] The Ni-based superalloy is a material that precipitates the γ'phase through aging treatment, thereby improving the strength and wear resistance at high temperatures. Ni-based superalloys are expensive but have extremely high heat resist...

Claims

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Application Information

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