阅读说明：本技术 一种高导热耐磨损的气门导管材料及其制作工艺 (High-heat-conductivity wear-resistant valve guide pipe material and manufacturing process thereof ) 是由 薛飞 李�诚 李勇 王宏庆 孙玲 姜武松 杨喆 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种高导热耐磨损的气门导管材料及其制作工艺,由下述质量百分比配比的元素原料：C：0.3～2.8％、S：0.25～4.0％、Mo：0.5～5.0％、Cu：15.0～40.0％、Cr:0.1～5.0％、W:0.3～2.5％、Fe：余量,以及不可避免的杂质组成；所述气门导管具有金相组织,其包含珠光体基体、固体润滑剂、碳化物硬质相、高铜组分、合金强化硬质相。本发明的高铜组分使得热导率高,能将高温热负荷及时有效传递至缸盖,降低气门导管的实际工作温度,配合含Cr、W的合金强化硬质相,结合回火处理的温度、时间,从而显著提高了高温耐磨损性能,适用工况更加恶劣的天然气发动机。(The invention discloses a high-heat-conductivity wear-resistant valve guide pipe material and a manufacturing process thereof, wherein the valve guide pipe material is prepared from the following element raw materials in percentage by mass: c: 0.3-2.8%, S: 0.25 to 4.0%, Mo: 0.5 to 5.0%, Cu: 15.0 to 40.0%, 0.1 to 5.0% Cr, 0.3 to 2.5% W, Fe: the balance, and unavoidable impurities; the valve guide pipe has a metallographic structure which comprises a pearlite matrix, a solid lubricant, a carbide hard phase, a high copper component and an alloy reinforced hard phase. The high-copper component of the invention has high thermal conductivity, can effectively transmit high-temperature heat load to a cylinder cover in time, reduces the actual working temperature of the valve guide pipe, and combines the temperature and time of tempering treatment with the alloy strengthening hard phase containing Cr and W, thereby obviously improving the high-temperature wear resistance and being suitable for natural gas engines with worse working conditions.)

1. The high-heat-conductivity wear-resistant valve guide pipe material is characterized by comprising the following element raw materials in percentage by mass: c: 0.3-2.8%, S: 0.25 to 4.0%, Mo: 0.5 to 5.0%, Cu: 15.0 to 40.0%, 0.1 to 5.0% Cr, 0.3 to 2.5% W, Fe: the balance, and unavoidable impurities;

the valve guide pipe has a metallographic structure which comprises a pearlite matrix, a solid lubricant, a carbide hard phase, a high copper component and an alloy reinforced hard phase.

2. A high thermal conductivity wear resistant valve guide material as claimed in claim 1, wherein said carbide hard phase is comprised of a C-Fe compound.

3. The high thermal conductivity and wear resistance valve guide material as claimed in claim 1, wherein the solid lubricant is MoS₂。

4. A high thermal conductivity and wear resistance valve guide material as claimed in claim 1, wherein the alloy reinforced hard phase is composed of C-Cr-Mo-W compound.

5. A manufacturing process of the high-thermal-conductivity wear-resistant valve guide material according to claims 1-4, characterized by comprising the following steps:

weighing, sieving and mixing the alloy powder, the carbon powder, the solid lubricant and the iron-copper alloy powder according to the proportion;

pressing the mixed powder on a forming press to form a green body with a certain shape and strength;

sintering the pressed and formed green body at high temperature in a sintering furnace; tempering the sintered blank in a heat treatment furnace at 400-500 ℃ for 1-3 h;

and (3) carrying out vacuum oil immersion on the blank after the heat treatment, and then carrying out mechanical processing to obtain the valve guide pipe.

6. The manufacturing process of claim 5, wherein the sieving is performed by a 60-100 mesh sieve.

7. The manufacturing process of claim 5, wherein the mixing is performed by stirring and mixing on a V-shaped mixer for 20-50 minutes.

8. The manufacturing process according to claim 5, wherein the sintering temperature of the high-temperature sintering is 1040-1100 ℃, and the density after sintering is more than 6.6g/cm 3.

Technical Field

The invention relates to the technical field of powder metallurgy of automobile parts, in particular to a high-heat-conductivity wear-resistant valve guide pipe material and a manufacturing process thereof.

Background

Along with the increasing requirements of the country on environmental protection, the national six standards for automobile emission pollutants begin to be implemented, in addition, the international fuel price rises, the popularization of clean energy fuel engines such as natural gas and the like is increased, the natural gas engine is drier than the common fuel engine, the heat load is high, the exhaust temperature is high, higher requirements on high-temperature self-lubricating and wear-resisting properties are provided, if the abnormal abrasion of a valve guide pipe generated under the high-temperature drier working condition cannot be met, the air leakage, the power reduction and even the scrapping of the engine can be caused, and the corresponding upgrading and updating of the valve guide pipe material of the natural gas engine are required. The traditional iron-based powder metallurgy valve guide pipe has poor heat conductivity and is difficult to deal with the harsh high-temperature environment of a natural gas engine. The cast copper alloy is expensive, has the problems of early wear, eccentric wear and the like for a long time, and has poor applicability to natural gas engines. Therefore, the powder metallurgy valve guide pipe material which has better wear resistance under the high-temperature dry working condition of the natural gas engine needs to be developed and dealt with.

Disclosure of Invention

The invention aims to provide a high-heat-conductivity wear-resistant valve guide pipe material and a manufacturing process thereof, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

a high-heat-conductivity wear-resistant valve guide pipe material is prepared from the following element raw materials in percentage by mass: c: 0.3-2.8%, S: 0.25 to 4.0%, Mo: 0.5 to 5.0%, Cu: 15.0 to 40.0%, 0.1 to 5.0% Cr, 0.3 to 2.5% W, Fe: the balance, and unavoidable impurities;

the valve guide pipe has a metallographic structure which comprises a pearlite matrix, a solid lubricant, a carbide hard phase, a high copper component and an alloy reinforced hard phase.

As a further scheme of the invention: the carbide hard phase consists of a C-Fe compound.

As a further scheme of the invention: the solid lubricant is MoS₂。

As a further scheme of the invention: the alloy strengthening hard phase consists of C-Cr-Mo-W compounds.

The manufacturing process of the high-thermal-conductivity wear-resistant valve guide pipe comprises the following steps:

weighing, sieving and mixing the alloy powder, the carbon powder, the solid lubricant and the iron-copper alloy powder according to the proportion;

pressing the mixed powder on a forming press to form a green body with a certain shape and strength;

sintering the pressed and formed green body at high temperature in a sintering furnace; tempering the sintered blank in a heat treatment furnace at 400-500 ℃ for 1-3 h;

and (3) carrying out vacuum oil immersion on the blank after the heat treatment, and then carrying out mechanical processing to obtain the valve guide pipe.

As a further scheme of the invention: the sieving is realized by a 60-100 mesh sieve.

As a further scheme of the invention: the mixing is carried out on a V-shaped mixer, and the mixing time is 20-50 minutes.

As a further scheme of the invention: the sintering temperature of the high-temperature sintering is 1040-1100 ℃, and the density after sintering is more than 6.6g/cm 3.

Compared with the prior art, the invention has the beneficial effects that: the high-copper component of the invention has high thermal conductivity, can effectively transmit high-temperature heat load to a cylinder cover in time, reduces the actual working temperature of the valve guide pipe, and combines the temperature and time of tempering treatment with the alloy strengthening hard phase containing Cr and W, thereby obviously improving the high-temperature wear resistance and being suitable for the harsh working condition of a natural gas engine; the natural gas engine is dry compared with the common fuel engine, and the copper component and the MoS with self-lubricating property in the invention₂The solid lubricant improves the high-temperature abrasion environment; the pearlite matrix with the carbide hard phase uniformly distributed is obtained according to the designed formula materials and the preparation process, and the pearlite matrix has good wear resistance and good machinability of a cutting machine; the Cu element iron-copper alloy powder is added in a form, so that the forming performance is better, the copper infiltration process is omitted, and the flow of the manufacturing process is simplified; the valve guide pipe material effectively improves the high-temperature wear-resistant self-lubricating and easy-machining performance of the powder metallurgy guide pipe, meets the national emission standard, can meet the engine requirements of turbocharging, lean combustion, direct injection in a cylinder and the like with strict requirements, and is suitable for natural gas engines with worse working conditions.

Drawings

FIG. 1 is a metallographic structure diagram of example 3 of the present invention.

In the figure: 1-pearlite matrix, 2-solid lubricant, 3-carbide hard phase, 4-high copper component and 5-alloy reinforced hard phase.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The contents of all elements are reasonably controlled, the optimal structure and performance are obtained by matching with a heat treatment mode of tempering treatment at 400-500 ℃, a pearlite structure with uniformly distributed carbide hard phases provides necessary strength and hardness for a matrix, a high-copper component and a solid lubricant optimize a high-temperature wear environment, and a hard phase is strengthened by matching with an alloy containing Cr and W, so that the high-temperature wear resistance is obviously improved. In the invention, C not only is alloyed with the matrix Fe to provide necessary strength, hardness and wear resistance, but also forms alloy carbide with Cr, Mo and W to improve the wear resistance, and if the carbon content ratio is controlled to be low, the wear resistance is obviously reduced; if the carbon content ratio is controlled to be high, the machining performance of the cutting machine is greatly reduced, and the abrasion of the matched valve is aggravated. When the proper content proportion of C and other alloy elements is ensured, if the heat treatment mode is improper, the carbide is unevenly distributed, the carbide form is poor, and finally the wear resistance is obviously reduced. S contributes to chip breaking and can improve machinability, but too much can lead to hot shortness. The Cu element is added in the form of the inventive iron-copper alloy powder, the forming performance is good, the copper infiltration process is omitted, the heat conduction performance of the guide pipe can be obviously improved due to high Cu content, the actual working temperature of the valve guide pipe is reduced by transferring heat to a cylinder cover, the high-temperature abrasion environment is optimized, but when the Cu content is too high, the valve guide pipe is softened, and although the high-temperature abrasion environment is improved, the abrasion resistance of the valve guide pipe is sharply reduced; the high-temperature wear-resistant alloy has the advantages that the high-copper composition is used for combining the alloy containing Cr and W to strengthen the hard phase, so that the high-temperature wear-resistant performance is obviously improved. Therefore, the present invention is not only a valve guide capable of achieving high-temperature wear resistance by increasing the elements such as C, Cu, Cr, Mo, and W, but also a valve guide capable of achieving high-temperature wear resistance by strictly controlling the proportional contents of the elements, particularly the Cu content, in accordance with a preferable tempering method and by allowing the elements to cooperate with each other.

A high-heat-conductivity wear-resistant valve guide pipe material is prepared from the following element raw materials in parts by mass: c: 0.3-2.8%, S: 0.25 to 4.0%, Mo: 0.5 to 5.0%, Cu: 15.0 to 40.0%, 0.1 to 5.0% Cr, 0.3 to 2.5% W, Fe: the balance, and unavoidable impurities; the valve guide pipe has a metallographic structure which comprises a pearlite matrix 1, a solid lubricant 2, a carbide hard phase 3, a high-copper component 4 and an alloy reinforced hard phase 5, wherein the carbide hard phase formed in situ is uniformly distributed in the pearlite matrix.

The C element and the matrix iron element form a pearlite matrix and a carbide hard phase to provide necessary strength and hardness for the matrix, and form fine carbide with alloy elements Cr and W to remarkably improve the wear resistance of the material.

The S element improves the chip breaking capacity of the valve guide pipe and improves the machining performance.

The Mo element can refine crystal grains and improve the strength, hardness, high temperature resistance and wear resistance of a base material on one hand, and can improve the high-temperature thermal stability of the valve guide pipe on the other hand.

The Cu element has self-lubricating property, and is combined with higher heat-conducting property of the high-copper component, so that the high-temperature wear-resisting environment of a natural gas engine, which is drier than that of a common fuel engine, is improved, the high-temperature wear-resisting property of the valve guide pipe is obviously improved, and the high-copper component is matched with an alloy containing Cr and W to strengthen a hard phase, so that the high-temperature wear-resisting property is obviously improved.

The Cr and W elements can form fine carbide with C, so that the hardness and the wear resistance of a base material are improved, the corrosion resistance of the material is obviously improved by the Cr, the high-temperature stability and the wear resistance of the W element are better, the Cr and the W element are matched, and the high-temperature wear-resistant corrosion performance of the valve guide pipe is obviously improved by optimizing a high-temperature wear environment by the Cu.

The manufacturing process of the high-thermal-conductivity wear-resistant valve guide pipe material comprises the following steps:

weighing alloy powder, carbon powder, solid lubricant and iron-copper alloy powder according to a proportion, sieving the alloy powder by a mesh sieve of 60-100 meshes to prevent powder agglomeration and foreign matter mixing, and stirring and mixing the sieved powder on a V-shaped mixer for 20-50 minutes; then, pressing the mixed powder on a forming press to form a green body with a certain shape and strength, sintering the formed green body in a sintering furnace at a high temperature of 1040-1100 ℃, mainly performing solid-phase sintering on the formed green body during sintering, wherein the density after sintering is more than 6.6g/cm3, tempering the sintered blank in a heat treatment furnace at a tempering temperature of 400-500 ℃ for 1-3 h, wherein the tempering aims are stress relief, carbide precipitation promotion and carbide morphology control, the hardness after tempering is 75-105 HB, and the radial crushing strength is more than 500 MPa; and (3) performing vacuum oil immersion on the blank after heat treatment, roughly grinding the outer circle of the guide pipe by using a grinding machine, processing the length and the inner and outer chamfers by using a numerical control lathe, finely grinding the outer circle by using a centerless grinding machine to prepare the valve guide pipe, and finally performing oil immersion and packaging.

Example 1

The high-thermal-conductivity wear-resistant valve guide pipe material provided by the embodiment is prepared from the following element raw materials in parts by mass: c: 0.5%, S: 0.6%, Mo: 0.9%, Cu: 19%, Cr 1%, W0.5%, Fe: the balance, and inevitable impurities.

The valve guide pipe in the embodiment 1 is prepared from the raw materials according to the preparation process, wherein the tempering temperature adopted in the tempering treatment in the preparation process of the embodiment is 450 degrees, and the tempering time is 2 hours.

Example 2

The manufacturing process and the temperature and time of the tempering treatment used in this embodiment are the same as those of embodiment 1, and the difference between this embodiment and embodiment 1 is that the selected element ratios are different, as shown in table 1.

Example 3

The manufacturing process and the temperature and time of the tempering treatment used in this embodiment are the same as those of embodiment 1, and the difference between this embodiment and embodiment 1 is that the selected element ratios are different, as shown in table 1.

Comparative example 1

The manufacturing process and the tempering temperature and time adopted in the comparative example are the same as those in the embodiment 3, and the difference between the embodiment and the embodiment 3 is that the selected element proportions are different, and the specific formula is shown in table 1.

Comparative example 2

The manufacturing process and the tempering temperature and time adopted in the comparative example are the same as those in the embodiment 3, and the difference between the embodiment and the embodiment 3 is that the selected element proportions are different, and the specific formula is shown in table 1.

Comparative example 3

The element proportion and the manufacturing process of the comparative example are the same as those of example 3 and the manufacturing process of the comparative example 3, except that the tempering temperature adopted in the comparative example is 250 ℃, and the tempering time is 2 hours, which is specifically shown in table 1.

Comparative example 4

The element ratio of the comparative example is the same as that of example 3, and the other manufacturing processes are the same as those of example 3, except that the comparative example is not tempered, as shown in table 1.

Comparative example 5

The comparative example uses an iron-based reference material valve guide.

Comparative example 6

The comparison example uses brass reference material valve guide.

TABLE 1

The abrasion resistance tests were conducted on examples 1 to 3 and comparative examples 1 to 6 under the conditions of a temperature of 250 c, a number of revolutions of 2000rpm, a test time of 10 hours, a valve guide abrasion tester as a test apparatus, and the test results are shown in table 2 below.

TABLE 2

	Thermal conductivity W/(m.K)	Valve guide wear mm	Valve wear capacity mm	Total wear rate mm
					Example 1	42	0.013	0.005	0.018
Example 2	56	0.011	0.004	0.015
					Example 3	52	0.009	0.003	0.012
Comparative example 1	63	0.081	0.002	0.083
					Comparative example 2	52	0.020	0.006	0.026
Comparative example 3	52	0.028	0.015	0.043
					Comparative example 4	52	0.036	0.019	0.067
Comparative example 5	28	0.065	0.025	0.09
					Comparative example 6	85	0.015	0.005	0.02

From the test data, the powder metallurgy valve guide material obtained in the embodiments 1 to 3 of the invention effectively improves the thermal conductivity compared with the iron-based reference material, and shows better wear resistance under high-temperature working conditions. From comparative example 1, it is clear that Cu plays an important role in high temperature wear. It is understood from example 3 and comparative examples 1 and 2 that the copper component and the alloy strengthening hard phase containing Cr and W act synergistically to improve the high-temperature wear resistance, and it is understood from example 3 and comparative examples 3 and 4 that the importance of the preferable tempering process is important. Compared with the existing iron-based material conduit, the heat conductivity and the wear resistance are both obviously improved. Compared with a copper guide pipe, the metallographic structure shown in fig. 1 shows that the high-copper component has high heat conductivity, the high-temperature wear environment is improved, the matrix structure and the wear-resistant phase ensure better wear resistance, the requirements of engines with strict requirements such as turbocharging, lean combustion and direct injection in a cylinder can be met, and the natural gas engine is applicable to natural gas engines with worse working conditions.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.