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Heat resistant steel for exhaust valve

A technology of heat-resistant steel and exhaust valve, applied in the field of heat-resistant steel, can solve the problems of poor hot workability, difficult to control texture, etc.

Inactive Publication Date: 2011-09-28
DAIDO STEEL CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, regarding LV21-43 steel, there are still problems that it is difficult to control the texture and it has 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 to 24 and comparative example 1 to 16

[0110] [Preparation of samples]

[0111] Each alloy having the composition shown in Tables 1 and 2 was melted in a high-frequency induction furnace to obtain a 50 kg ingot. Each ingot prepared by melting was subjected to a homogenization heat treatment at 1,180° C. for 16 hours. Then, the ingot was forged into a rod stock having a diameter of 18 mm. The forged material is further subjected to solution treatment (ST). Solution treatment at 1,050°C for 30 minutes followed by oil cooling (Examples 1 to 24), or solution treatment at 1,050°C for 30 minutes followed by oil cooling (Comparative Examples 1 to 24) 16). In addition, the material after solution treatment (ST) was subjected to aging treatment (AG) at 750° C. for 4 hours, and then air-cooled.

[0112] Table 1

[0113]

[0114] Table 2

[0115]

[0116] [2. Test method]

[0117] [2.1. Hardness]

[0118] The hardness at normal temperature was measured using the C grade of the Rockwell hardness tester. In addit...

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Abstract

The present invention provides a heat resistant steel for an exhaust valve, containing: more than 0.50% by mass but less than 0.80% by mass of C, more than 0.30% by mass but less than 0.60% by mass of N, 17.0% by mass or more but less than 25.0% by mass of Cr, 4.0% by mass or more but less than 12.0% by mass of Ni, 7.0% by mass or more but less than 14.0% by mass of Mn, 2.0% by mass or more but less than 6.0% by mass of Mo, more than 0.5% by mass but less than 1.5% by mass of Si, and 0.025% by mass or more but less than 1.0% by mass of Nb, with the balance consisting of Fe and unavoidable impurities, in which a content of P contained in the unavoidable impurities is regulated to less than 0.03% by mass, a total content of C and N is from 0.85% by mass to 1.3% by mass, and a ratio of the content of Nb to the content of C is 0.05 or more but less than 1.8.

Description

technical field [0001] This invention relates to heat resistant steel for exhaust valves. Background technique [0002] An intake valve for introducing a mixture of fuel and air into a cylinder, and an exhaust valve for discharging combustion gas to the outside of the cylinder have been used in the engine. Among them, since the exhaust valve is exposed to high-temperature fuel gas, materials having excellent high-temperature characteristics such as high-temperature hardness, fatigue characteristics, wear resistance, and oxidation resistance have been used in the exhaust valve. As materials for the exhaust valve, Ni-based superalloys (for example, NCF751), austenitic heat-resistant steels (for example, SUH35) and the like are known. [0003] A Ni-based superalloy is a material in which the γ' phase is precipitated by aging treatment, thereby enhancing its strength and wear resistance at high temperatures. Ni-based superalloys are expensive, but have extremely high heat resi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/58
CPCC22C38/02F01L2820/00C22C38/48C21D9/0068F01L2103/00F01L3/02C22C38/58C22C38/001C22C38/44F01L2303/00
Inventor 大崎元嗣植田茂纪露无崇志
Owner DAIDO STEEL CO LTD
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