CN110592456B

CN110592456B - High-temperature-resistant exhaust valve and production method thereof

Info

Publication number: CN110592456B
Application number: CN201910824649.8A
Authority: CN
Inventors: 张志勇; 张绵胜
Original assignee: Special Metallurgical Beijing Technology Development Co ltd
Current assignee: Special Metallurgical Beijing Technology Development Co ltd
Priority date: 2019-09-02
Filing date: 2019-09-02
Publication date: 2021-05-25
Anticipated expiration: 2039-09-02
Also published as: CN110592456A

Abstract

The invention discloses a high-temperature-resistant exhaust valve, wherein the metallographic structure is austenite, carbides of a valve disk part are uniformly distributed and are not in a net shape, the grain size reaches 8 grades, and the high-temperature-resistant exhaust valve comprises the following chemical components in percentage by weight: 0.004-0.15 percent of C, 0.40-1.20 percent of Si, 0.50-1.0 percent of Mn, 20.5-25.0 percent of Cr, 30.5-35.0 percent of Ni, 2.5-3.0 percent of Ti, 1.0-2.0 percent of Al, 0.015-0.50 percent of V, 0.65-1.50 percent of W, 0.16-0.60 percent of Mo, and the balance of Fe. The valve has good wear resistance and mechanical property, can meet the requirements of exhaust valves of diesel and gas internal combustion engines, and has the advantage of long service life.

Description

High-temperature-resistant exhaust valve and production method thereof

Technical Field

The invention relates to an exhaust valve, in particular to a high-temperature-resistant exhaust valve.

Background

The exhaust valve of the valve train of the internal combustion engine is an important moving part of the engine and is subject to high temperature, impact and friction, so that the service condition of the exhaust valve is harsh and the working environment is severe. The exhaust valve not only needs to have high-temperature strength and thermal stability, but also needs to have excellent wear resistance, oxidation resistance and corrosion resistance so as to ensure air tightness and service life.

The internal combustion engine of ships and generator sets uses fuel, such as heavy oil and various gas sources, such as gas and methane, besides diesel oil, and compared with the diesel oil, the internal combustion engine has high combustion temperature and has stronger abrasiveness of impurities. These internal combustion engines are characterized by high power but high combustion temperature, which puts higher demands on the service life of the valves. The service life of the existing exhaust valve is generally 5000h, and the existing exhaust valve cannot meet the future development requirements of the internal combustion engine. Particularly, the adoption of fuel gas reduces the lubricating components in the emissions and has higher requirements on the wear resistance. Therefore, there is a need for an exhaust valve for an internal combustion engine that has high wear resistance and long life in high temperature environments.

Teyi (Beijing) science and technology development Limited company has more than twenty years of experience in the field of internal combustion engine valve manufacturing, and obtains Chinese invention patent with patent number 03123795.9 'diesel locomotive diesel oil bimetallic exhaust valve and manufacturing method thereof' in 2003. According to the requirements of the development of internal combustion engines in recent years and combined with research and study for many years, a new valve is developed to meet the requirements of high temperature, high wear resistance and long service life.

Disclosure of Invention

The invention aims to provide a high-temperature-resistant exhaust valve and a production method thereof, and the service life of the high-temperature-resistant exhaust valve can reach 8000 h.

The high-temperature-resistant exhaust valve is a super iron-nickel alloy with a trademark of TS913B, the metallographic structure is austenite, carbides of the valve disk part are uniformly distributed and are not in a net shape, the grain size reaches 8 grades, and the high-temperature-resistant exhaust valve comprises the following chemical components in percentage by weight: 0.004-0.15 percent of C, 0.40-1.20 percent of Si, 0.50-1.0 percent of Mn, 20.5-25.0 percent of Cr, 30.5-35.0 percent of Ni, 2.5-3.0 percent of Ti, 1.0-2.0 percent of Al, 0.015-0.50 percent of V, 0.65-1.50 percent of W, 0.16-0.60 percent of Mo, and the balance of Fe.

Preferably, according to a large number of experimental studies, on the basis of ensuring the mechanical performance and the service life required by users, in order to further reduce the cost, the chemical components are controlled as follows according to the weight percentage: 0.008-0.12 percent of C, 0.4-0.8 percent of Si, 0.5-0.7 percent of Mn, 20.5-22.0 percent of Cr, 30.5-35.0 percent of Ni, 2.5-3.0 percent of Ti, 1.0-1.20 percent of Al, 0.1-0.5 percent of V, 0.65-1.00 percent of W, 0.16-0.50 percent of Mo, and the balance of Fe.

Most preferably, the chemical components are as follows by weight percent: 0.08 percent of C, 0.6 percent of Si, 0.6 percent of Mn, 21 percent of Cr, 33 percent of Ni, 2.8 percent of Ti, 1.0 percent of Al, 0.3 percent of V, 0.8 percent of W, 0.3 percent of Mo, and the balance of 3 percent of Fe.

The heat treatment is a key factor for ensuring the formation of the metallographic structure and the mechanical property, the valve is produced by adopting bars through electric upsetting forming, heat treatment and mechanical processing, and the key treatment process comprises the following steps:

(1) electric upsetting: heating the die at the temperature of 250-;

(2) post-pier heat treatment: and (3) carrying out aging treatment on the electrically upset valve blank at the aging temperature of 680-760 ℃, keeping the temperature for 5-8 hours, and then air-cooling to room temperature.

The normal temperature performance of the TS913 exhaust valve is as follows: the tensile strength is more than or equal to 1170MPa, the yield strength is more than or equal to 840MPa, the elongation is more than or equal to 20 percent, the end face shrinkage is more than or equal to 30 percent, the grain size after heat treatment is more than or equal to 8 grade, and the normal temperature hardness is 35-40 HRC. The high-temperature hardness at 650 ℃ is more than or equal to 345HV 5. Has excellent high-temperature hardness, abrasion resistance and high-temperature resistance. The service life can reach 6000-.

Detailed Description

The present invention will be further described with reference to specific examples to assist understanding of the invention.

The high-temperature resistant exhaust valve is a super iron-nickel alloy, the metallographic structure is austenite, carbides of a valve disc part are uniformly distributed and are not in a net shape, the grain size reaches 8 grades, and the high-temperature resistant exhaust valve comprises the following chemical components in percentage by weight: 0.004-0.15 percent of C, 0.40-1.20 percent of Si, 0.50-1.0 percent of Mn, 20.5-25.0 percent of Cr, 30.5-35.0 percent of Ni, 2.5-3.0 percent of Ti, 1.0-2.0 percent of Al, 0.015-0.50 percent of V, 0.65-1.50 percent of W, 0.16-0.60 percent of Mo, and the balance of Fe.

The production process comprises electric upsetting and heat treatment after the electric upsetting, and comprises the following steps:

(1) electric upsetting: heating the die at the temperature of 250-;

The alloy elements used in the different examples are as follows in table 1:

TABLE 1 composition of alloying elements for different examples

The products of the above examples and comparative examples were examined using a 600KN universal material testing machine, a rockwell hardness tester, a metallographic microscope, and an overhead life test, the life test using a 0.02mm reduction in the pan head thickness as a condition for achieving the life, and the specific results are shown in table 2.

TABLE 2 mechanical Properties and service lives of the products of the examples

By comparison, the inventive examples 1-5 had higher mechanical properties and longer practical life than the comparative examples.

Claims

1. A high temperature resistant exhaust valve, the metallographic structure is austenite, the valve disk carbide distributes evenly and is not netted, the grain size reaches 8 grades, its chemical composition is according to the weight percent: 0.004-0.15 percent of C, 0.40-1.20 percent of Si, 0.50-1.0 percent of Mn, 20.5-25.0 percent of Cr, 30.5-35.0 percent of Ni, 2.5-3.0 percent of Ti, 1.0-2.0 percent of Al, 0.015-0.50 percent of V, 0.65-1.50 percent of W, 0.16-0.60 percent of Mo, and the balance of Fe.

2. The high-temperature-resistant exhaust valve according to claim 1, characterized in that the chemical components are controlled by weight percent as follows: 0.008-0.12 percent of C, 0.4-0.8 percent of Si, 0.5-0.7 percent of Mn, 20.5-22.0 percent of Cr, 30.5-35.0 percent of Ni, 2.5-3.0 percent of Ti, 1.0-1.20 percent of Al, 0.1-0.5 percent of V, 0.65-1.00 percent of W, 0.16-0.50 percent of Mo, and the balance of Fe.

3. The high-temperature-resistant exhaust valve according to claim 1, characterized in that the chemical components are controlled by weight percent as follows: the chemical components by weight percentage are as follows: 0.08 percent of C, 0.6 percent of Si, 0.6 percent of Mn, 21 percent of Cr, 33 percent of Ni, 2.8 percent of Ti, 1.0 percent of Al, 0.3 percent of V, 0.8 percent of W, 0.3 percent of Mo, and the balance of Fe.

4. A method for producing the high-temperature-resistant exhaust valve as claimed in one of claims 1 to 3, wherein a bar material is produced through electric upsetting forming, heat treatment and machining, and the following scheme is adopted for the heat treatment after the electric upsetting and the upsetting:

(1) electric upsetting: heating the die at the temperature of 250-;

(2) heat treatment after upsetting: and (3) carrying out aging treatment on the electrically upset valve blank at the aging temperature of 680-760 ℃, keeping the temperature for 5-8 hours, and then air-cooling to room temperature.