阅读说明：本技术 一种抗疲劳双金属轴瓦材料及其制备方法 (Anti-fatigue bimetallic bearing bush material and preparation method thereof ) 是由 周健 王赞 董樑 芮云鹏 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种抗疲劳双金属轴瓦材料及其制备方法,轴瓦材料由钢基底和铜合金层组成,铜合金层通过电弧沉积熔覆于钢基底表面,铜合金层与钢基底在宽度方向的结合面呈拱形。制备方法包括如下步骤：制备耐磨铜层成分的药芯焊丝；对钢基底材料进行清洗,去除氧化物和油污；使用焊接机器人在钢基底上进行增材制造抗疲劳层,焊丝和钢基底的表层在高温电弧的作用下熔化并形成熔池,二者发生熔化,实现冶金结合。本发明提供的抗疲劳双金属轴瓦无铅环保、抗疲劳性能高、提供的制备方法生产效率高,且能够显著提高双金属复合材料的结合强度,制备的抗疲劳双金属轴瓦材料可很好地应用于内燃机轴瓦中。(The invention discloses an anti-fatigue bimetallic bearing bush material and a preparation method thereof. The preparation method comprises the following steps: preparing a flux-cored wire with a wear-resistant copper layer component; cleaning a steel substrate material to remove oxides and oil stains; the welding robot is used for additive manufacturing of the anti-fatigue layer on the steel substrate, the welding wire and the surface layer of the steel substrate are melted under the action of the high-temperature electric arc to form a molten pool, and the welding wire and the surface layer of the steel substrate are melted to realize metallurgical bonding. The anti-fatigue bimetallic bearing bush provided by the invention is lead-free and environment-friendly, has high anti-fatigue performance, the provided preparation method has high production efficiency, the bonding strength of the bimetallic composite material can be obviously improved, and the prepared anti-fatigue bimetallic bearing bush material can be well applied to the bearing bush of an internal combustion engine.)

1. An anti-fatigue bimetallic bearing bush material is characterized in that: the copper alloy layer is clad on the surface of the steel substrate through arc deposition, the combination surface of the copper alloy layer and the steel substrate in the width direction is in an arch shape, the ratio of the thickness of the copper alloy layer in the middle to the thickness of the copper alloy layers on the two side edges is 0.5-0.8, and the thickness range of the copper alloy layer in the middle is 0.1-0.35 mm.

2. The fatigue-resistant bimetallic bearing shell material as claimed in claim 1, wherein the copper alloy layer comprises the following components, in percentage by weight, Bi: 6-12%, Sn: 5-8%, Ag: 0.1-0.3%, Ti: 0.1-0.3%, B: 0.1-0.3%, and the balance of Cu.

3. The fatigue-resistant bimetallic bearing shell material of claim 1, wherein: the steel substrate is made of low-carbon steel, and the carbon content is 0.1-0.3 wt%.

4. A method of producing a fatigue bimetallic bearing shell material as claimed in any one of claims 1 to 3, characterised by the steps of:

step 1, preparing a flux-cored wire;

step 2, taking a steel substrate material, and cleaning the surface of the steel substrate material;

and 3, melting the flux-cored welding wire into molten drops under the action of the electric arc, dropping the molten drops onto the surface of the steel substrate, partially melting the surface of the steel substrate, forming a molten pool together with the molten drops, and cooling and solidifying the molten pool under the protective atmosphere to form the bimetallic bearing bush material.

5. The method for preparing the fatigue bimetallic bearing shell material as claimed in claim 4, wherein in the step 3: the current during arc deposition is 60-100A, the voltage is 5-10V, and the welding speed is 15-20 cm/min; the linear energy of arc deposition is 900-4000J/cm.

6. The method for preparing the fatigue bimetallic bearing shell material as claimed in claim 4, wherein in the step 3: the protective atmosphere is argon, and the gas flow is 15-20L/min.

7. The preparation method of the fatigue bimetallic bearing bush material as claimed in claim 4, wherein in the step 1, the specific preparation process of the flux-cored wire is as follows:

(1) putting high-purity bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder into a metal tank in proportion and carrying out preliminary stirring;

(2) putting the metal can filled with the mixed powder into a planetary high-energy ball mill for ball milling;

(3) and (3) wrapping the uniformly mixed metal powder into a flux-cored welding wire rough blank by using a red copper sheet, and then carrying out hot drawing to form the flux-cored welding wire.

8. The preparation method of the fatigue bimetallic bearing shell material as claimed in claim 7, characterized in that: in the step (1), the mass ratio of bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder is 12: 8: 03: 0.3: 0.3: 45-50 parts of; wherein the granularity of each metal powder is 800-1000 meshes.

9. The preparation method of the fatigue bimetallic bearing shell material as claimed in claim 7, characterized in that: in the step (2), the ball milling speed is 400-500 rad/min, and the ball milling time is 2-3 h.

10. The preparation method of the fatigue bimetallic bearing shell material as claimed in claim 4, characterized in that: in the step 2, the thickness of the steel substrate is 1-3 mm.

Technical Field

The invention belongs to the preparation of metal materials, and particularly relates to an anti-fatigue bimetallic bearing bush material and a preparation method thereof.

Background

The bimetallic material of the bearing bush of the internal combustion engine and the like is divided into two categories of copper/steel and aluminum/steel. The former has stronger bearing capacity and is often applied to the working condition of low speed and heavy load. Because of the problem of environmental protection, the use of leaded tin bronzes with antifriction and wear-resistant characteristics is limited, and the development of lead-free tin bronzes is gradually accelerated. The tribological performance and the mechanical performance of the material are always in contradiction, and when the bearing performance and the fatigue resistance of the bearing bush material are improved, the compliance, the embedding performance and the seizure resistance of the material are generally reduced. The adoption of the multilayer composite material is an effective way for optimizing the comprehensive performance of the bearing bush, and good application effects are obtained, but the more the composite layers are, the better the composite layers are, and besides the complex process and the long flow path, the interlayer bonding part is also a weak link which causes the failure of the bearing bush.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a bimetal bearing bush material with an arched joint surface and high fatigue resistance; the second purpose of the invention is to provide a preparation method of the bearing bush material.

The technical scheme is as follows: the anti-fatigue bimetallic bearing bush material comprises a steel substrate and a copper alloy layer, wherein the copper alloy layer is cladded on the surface of the steel substrate through arc deposition, the combination surface of the copper alloy layer and the steel substrate in the width direction is in an arch shape, the ratio of the thickness of the copper alloy layer in the middle part to the thickness of the copper alloy layers on the two side parts is 0.5-0.8, and the thickness range of the copper alloy layer in the middle part is 0.1-0.35 mm.

Further, the copper alloy layer comprises the following components in percentage by weight: 6-12%, Sn: 5-8%, Ag: 0.1-0.3%, Ti: 0.1-0.3%, B: 0.1-0.3%, and the balance of Cu. The steel substrate is made of low-carbon steel, and the carbon content is 0.1-0.3 wt%.

The invention also provides a preparation method of the fatigue bimetallic bearing bush material, which comprises the following steps:

step 1, preparing a flux-cored wire;

step 2, taking a steel substrate material, and cleaning the surface of the steel substrate material;

and 3, melting the flux-cored welding wire into molten drops under the action of the electric arc, dropping the molten drops onto the surface of the steel substrate, partially melting the surface of the steel substrate, forming a molten pool together with the molten drops, and cooling and solidifying the molten pool under the protective atmosphere to form the bimetallic bearing bush material.

Further, in the step 3: the current during arc deposition is 60-100A, the voltage is 5-10V, and the welding speed is 15-20 cm/min; the linear energy of arc deposition is 900-4000J/cm.

Further, in the step 3: the protective atmosphere is argon, and the gas flow is 15-20L/min.

Further, in the step 1, the specific preparation process of the flux-cored wire is as follows:

(1) putting high-purity bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder into a metal tank in proportion and carrying out preliminary stirring;

(2) putting the metal can filled with the mixed powder into a planetary high-energy ball mill for ball milling;

(3) and (3) wrapping the uniformly mixed metal powder into a flux-cored welding wire rough blank by using a red copper sheet, and then carrying out hot drawing to form the flux-cored welding wire.

Further, in the step (1), the mass ratio of bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder is 12: 8: 03: 0.3: 0.3: 45-50 parts of; wherein the granularity of each metal powder is 800-1000 meshes.

Further, in the step (2), the ball milling speed is 400-500 rad/min, and the ball milling time is 2-3 h.

Further, in the step 2, the thickness of the steel substrate is 1-3 mm.

The preparation principle of the invention is as follows: referring to fig. 1, during arc deposition, the weld end stays longer on both sides of the weld bead than in the middle of the weld bead, so the amount of molten steel substrate is greater at both sides and more copper is deposited on the steel substrate, eventually forming an arcuate interface. The arc of the arc interface is mainly influenced by the energy of an arc deposition line, the larger the line energy is, the larger the melting amount of a steel substrate and the deposition amount of copper are increased, and finally, the larger the arc of the arc is, the method for calculating the line energy is as follows: (voltage x current)/welding speed, calculated in units of V, A and cm/s, respectively. Generally, the energy of the arc deposition is preferably 900 to 4000J/cm because the energy of the arc deposition is as low as possible to ensure the formability. In the presence of the arched interface, the interface bonding force of two materials with larger physical property difference between copper and steel can be improved, and the problem of bearing bush failure caused by cracking and even stripping of a copper alloy layer under the coupling action of working condition factors such as stress, temperature and the like is reduced. The arch interface is also beneficial to dispersing the stress borne on the interface, so when the local internal stress of the interface is increased, the risk of interface cracking is reduced, the central part of the bearing bush is often thin in oil film, local specific pressure is higher, temperature is higher, the structural characteristics of the bearing bush can be damaged after copper alloy creep deformation, the instability probability of the rotating shaft is greatly increased, the thickness of the middle of the bimetallic material of the arch interface is small, the creep deformation amount is small, and the fatigue resistance of the bearing bush can be obviously improved. Generally, the greater the curvature of the arcuate interface, the better the load bearing, which also means that the copper layer is thinner in the middle and thicker on both sides. From the perspective of wear allowance, the thickness of the copper layer is not less than 0.1mm generally, and the copper layer cannot be too large, so that the phenomenon that the copper layer has too large thickness ratio and loses the contribution of the steel layer to keeping the structural rigidity of the bearing bush is avoided. Therefore, under the condition of keeping the copper/steel section proportion unchanged, the ratio of the thickness of the middle copper layer to the thickness of the copper layers at two sides is optimized to be 0.5-0.8 through the actual bearing performance and fatigue resistance performance test of the bearing bush, and the thickness range of the middle copper layer is 0.1-0.35 mm. In order to ensure that the subsequent machining processes such as turning and the like have enough copper layer thickness, the initial copper layer thickness of the bimetal sample prepared by the arc deposition process is more than 0.6 mm.

Meanwhile, the copper alloy layer of the invention adopts tin bronze containing Bi, but Bi is generally in a free state at a grain boundary in the copper alloy and has a coarse appearance, so that the Bi is easy to separate from the surface under the working condition of frictional wear to cause the wear rate of the material to be improved, and the mechanical property to be reduced; meanwhile, the three elements of Ag, Ti and B strengthen the crystal boundary and the Bi/Cu phase interface of the copper matrix, and the bonding strength of the copper/steel interface is improved, so that the mechanical property of the Bi-containing tin bronze can be greatly improved. The addition of the copper powder has the functions of supplementing the copper content and filling the internal gaps of the flux-cored wire.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: (1) the anti-fatigue bimetallic bearing bush provided by the invention is lead-free, environment-friendly and high in anti-fatigue performance, the production efficiency of the provided preparation method is high, the bonding strength of the bimetallic composite material can be obviously improved, and the prepared anti-fatigue bimetallic bearing bush material can be well applied to the bearing bush of an internal combustion engine; (2) according to the invention, by adding silver, titanium and boron into the copper alloy, the Bi phase can be refined, the grain boundary of a copper matrix and the Bi/Cu phase interface are strengthened, the wear resistance of the alloy is obviously improved, the hardness can reach more than 160HB, the yield strength can reach 280Mpa, and the bonding strength of the copper/steel interface can be improved by three elements, and can reach more than 300 MPa; (3) the invention can prepare the bimetallic bearing bush material with an arch-shaped joint surface by an electric arc additive manufacturing process, the bimetallic material with an arch-shaped interface has small middle thickness and small creep amount, the fatigue resistance of the bearing bush is obviously improved, and the fatigue limit of the bimetallic material sapphire reaches more than 190 MPa.

Drawings

FIG. 1 is a schematic view of a copper/steel arch junction surface;

FIG. 2 is a physical diagram of a copper/steel arch-shaped junction surface;

FIG. 3 is a pictorial representation of the bonding surface of comparative example 1;

FIG. 4 shows a Cu-10% Sn-5% Bi alloy block sintering process.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the accompanying drawings and examples.

Example 1

(1) Preliminary powder mixing: putting high-purity bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder with the powder granularity of 800-1000 meshes into a metal tank in proportion, and primarily stirring the powder in the tank by using a glass rod, wherein the proportion of each metal powder is 12: 8: 03: 0.3: 0.3: 47.7;

(2) ball milling and mixing: putting the pot filled with the mixed metal powder into a QM-3SP4 planetary high-energy ball mill for ball milling and mixing for 2 hours, so that the components are uniformly mixed, the rotating speed of the ball mill is 400rad/min during mixing, and the mixing is stopped for 20 minutes in the middle of 1 hour;

(3) and (3) wrapping the uniformly mixed metal powder into a flux-cored welding wire rough blank by using a red copper sheet, and carrying out hot drawing on the welding wire rough blank to obtain the flux-cored welding wire with the diameter of 1.2 mm.

(4) Pretreatment of a steel plate: selecting low-carbon steel with the carbon content of not more than 0.3 wt%, the mark Q235, the wall thickness of 2mm, the length of 200mm and the width of 20mm, and carrying out oil removal treatment on the surface;

(5) after the steel substrate is clamped and fixed, a copper alloy layer is arc-deposited on the steel substrate through a welding robot, the welding wire and the surface layer of the steel substrate are melted under the action of high-temperature arc to form a molten pool, the welding wire and the surface layer of the steel substrate are melted, and the molten pool is solidified to realize metallurgical bonding, so that the required anti-fatigue bimetallic bearing bush material can be obtained. Wherein the current is 80A, the voltage and the wire feeding speed are automatically matched with the current, the voltage is 8V, the welding speed is 18cm/min, and the control wire energy is 2100J/cm; high-purity argon is used as a protective gas, the gas flow is 18L/min, and the surface of the alloy is prevented from being oxidized in the deposition process.

Firstly, a sample with the total thickness of 2.5mm, the length of 200mm and the width of 20mm is prepared, the thickness of an initial copper layer is 0.7mm, and in order to ensure that the subsequent machining processes such as turning and the like have enough copper layer thickness, then the sample is milled and rolled, referring to a figure 1, a lead-free copper-based bimetal composite bearing bush material with the thickness of a middle copper layer of 0.2mm and the thickness of copper layers at two sides of 0.3mm is obtained, and referring to a figure 2, a copper/steel arch-shaped combination surface object diagram prepared in example 1 is obtained.

Example 2

(1) Preliminary powder mixing: putting high-purity bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder with the powder granularity of 800-1000 meshes into a metal tank in proportion, and primarily stirring the powder in the tank by using a glass rod, wherein the proportion of each metal powder is 12: 8: 03: 0.3: 0.3: 45, a first step of;

(2) ball milling and mixing: putting the pot filled with the mixed metal powder into a QM-3SP4 planetary high-energy ball mill for ball milling and mixing for 2 hours, so that the components are uniformly mixed, the rotating speed of the ball mill is 400rad/min during mixing, and the mixing is stopped for 20 minutes in the middle of 1 hour;

(3) and (3) wrapping the uniformly mixed metal powder into a flux-cored welding wire rough blank by using a red copper sheet, and carrying out hot drawing on the welding wire rough blank to obtain the flux-cored welding wire with the diameter of 1.2 mm.

(4) Pretreatment of a steel plate: selecting low-carbon steel with the carbon content of not more than 0.3 wt%, the mark Q235, the wall thickness of 2mm, the length of 200mm and the width of 20mm, and carrying out oil removal treatment on the surface;

(5) after the steel substrate is clamped and fixed, a copper alloy layer is arc-deposited on the steel substrate through a welding robot, the welding wire and the surface layer of the steel substrate are melted under the action of high-temperature arc to form a molten pool, the welding wire and the surface layer of the steel substrate are melted, and the molten pool is solidified to realize metallurgical bonding, so that the required anti-fatigue bimetallic bearing bush material can be obtained. Wherein the current is 60A, the voltage and the wire feeding speed are automatically matched with the current, the voltage is 5V, the welding speed is 20cm/min, and the energy of the control wire is 900J/cm; high-purity argon is used as protective gas, the gas flow is 20L/min, and the surface of the alloy is prevented from being oxidized in the deposition process. The thickness of the initial copper layer of the prepared bimetal sample is 0.6mm, and then the bimetal sample is milled and rolled to obtain the lead-free copper-based bimetal composite bearing bush material with the thickness of the middle copper layer of 0.2mm and the thickness of the copper layers at two sides of 0.25 mm.

Example 3

(1) Preliminary powder mixing: putting high-purity bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder with the powder granularity of 800-1000 meshes into a metal tank in proportion, and primarily stirring the powder in the tank by using a glass rod, wherein the proportion of each metal powder is 12: 8: 03: 0.3: 0.3: 50;

(2) ball milling and mixing: putting the pot filled with the mixed metal powder into a QM-3SP4 planetary high-energy ball mill for ball milling and mixing for 2.5 hours to uniformly mix the components, wherein the rotating speed of the ball mill is 450rad/min during mixing, and the ball mill is stopped for 20 minutes in the middle of 1 hour of mixing;

(3) and (3) wrapping the uniformly mixed metal powder into a flux-cored welding wire rough blank by using a red copper sheet, and carrying out hot drawing on the welding wire rough blank to obtain the flux-cored welding wire with the diameter of 1.2 mm.

(4) Pretreatment of a steel plate: selecting low-carbon steel with the carbon content of not more than 0.3 wt%, the mark Q235, the wall thickness of 2mm, the length of 200mm and the width of 20mm, and carrying out oil removal treatment on the surface;

(5) after the steel substrate is clamped and fixed, a copper alloy layer is arc-deposited on the steel substrate through a welding robot, the welding wire and the surface layer of the steel substrate are melted under the action of high-temperature arc to form a molten pool, the welding wire and the surface layer of the steel substrate are melted, and the molten pool is solidified to realize metallurgical bonding, so that the required anti-fatigue bimetallic bearing bush material can be obtained. Wherein the current is 100A, the voltage and the wire feeding speed are automatically matched with the current, the voltage is 10V, the welding speed is 15cm/min, and the energy of the control wire is 4000J/cm; high-purity argon is used as protective gas, the gas flow is 15L/min, and the surface of the alloy is prevented from being oxidized in the deposition process. The initial copper layer of the prepared bimetal sample is 0.9mm in thickness, and then the bimetal sample is milled and rolled to obtain the lead-free copper-based bimetal composite bearing bush material with the middle copper layer of 0.2mm in thickness and the copper layers on two sides of 0.4mm in thickness.

Example 4

(1) Preliminary powder mixing: putting high-purity bismuth powder, tin powder, silver powder, titanium powder, boron powder and copper powder with the powder granularity of 800-1000 meshes into a metal tank in proportion, and primarily stirring the powder in the tank by using a glass rod, wherein the proportion of each metal powder is 12: 8: 03: 0.3: 0.3: 47.7;

(2) ball milling and mixing: putting the pot filled with the mixed metal powder into a QM-3SP4 planetary high-energy ball mill for ball milling and mixing for 3 hours, so that the components are uniformly mixed, the rotating speed of the ball mill is 500rad/min during mixing, and the mixing is stopped for 20 minutes in the middle of 1 hour;

(3) and (3) wrapping the uniformly mixed metal powder into a flux-cored welding wire rough blank by using a red copper sheet, and carrying out hot drawing on the welding wire rough blank to obtain the flux-cored welding wire with the diameter of 1.2 mm.

(4) Pretreatment of a steel plate: selecting low-carbon steel with the carbon content of not more than 0.3 wt%, the mark Q235, the wall thickness of 2mm, the length of 200mm and the width of 20mm, and carrying out oil removal treatment on the surface;

(5) after the steel substrate is clamped and fixed, a copper alloy layer is arc-deposited on the steel substrate through a welding robot, the welding wire and the surface layer of the steel substrate are melted under the action of high-temperature arc to form a molten pool, the welding wire and the surface layer of the steel substrate are melted, and the molten pool is solidified to realize metallurgical bonding, so that the required anti-fatigue bimetallic bearing bush material can be obtained. Wherein the current is 80A, the voltage and the wire feeding speed are automatically matched with the current, the voltage is 8V, the welding speed is 15cm/min, and the energy of the control wire is 2560J/cm; high-purity argon is used as protective gas, the gas flow is 15L/min, and the surface of the alloy is prevented from being oxidized in the deposition process. The initial copper layer of the prepared bimetal sample is 0.75mm in thickness, and then the bimetal sample is milled and rolled to obtain the lead-free copper-based bimetal composite bearing bush material with the middle copper layer of 0.2mm in thickness and the copper layers on two sides of 0.32mm in thickness.

Comparative example 1

The components of the sample are Cu-10% Sn-7% Bi, and the sample is a lead-free copper-based high-performance bimetallic bearing bush prepared by a powder sintering method. The preparation process comprises the following steps: (1) preparing mixed powder from Cu powder, Sn powder and Bi powder according to a mass ratio, then filling the mixed powder into a planetary ball milling tank, and performing ball milling for 40 hours at a rotating speed of 450rpm and a process of ' ball milling for half an hour ', stopping the ball milling for half an hour '; (2) the alloy and the steel backing are compounded according to the process of powder laying, sintering, primary rolling, re-sintering and finish rolling: the powder spreading thickness is 1 mm; the initial rolling deformation amount is about 10 percent, the finish rolling deformation amount is about 5 percent, and the thickness of the final alloy strip is 2.50 +/-0.01 mm.

The cross section of the bearing bush sample prepared by the method is shown in figure 3, and is obviously different from the arched cross section of the embodiment 1. The sintering process parameters are shown in fig. 4, wherein (a) represents the first sintering process and (b) represents the block post-rolling re-sintering process.

The materials prepared in examples 1 to 4 and comparative example 1 were subjected to a performance test, wherein the sapphire fatigue limit test was carried out by performing a 30-minute no-load operation after the test bush was mounted on the sapphire bush fatigue testing machine, starting a load from 146MPa, detecting whether there was any macroscopic fatigue damage of the bush after 20 hours of operation, increasing a first-order load (7MPa) if there was no damage, continuing the test, and repeating the above steps until the fatigue damage of the bush was tested, and the bush load at the time of the fatigue damage of the bush was the fatigue strength of the material specimen on the sapphire bush fatigue testing machine. The hardness is tested by an FM-700 automatic microhardness measuring system, and the yield strength and the bonding strength are tested by a microcomputer control electronic universal tester with the model of CMT 5105. See table 1 for specific results.

TABLE 1 Performance test results of anti-fatigue bimetallic bearing bush materials

The results show that compared with the alloy components and the shape of the joint surface of the comparative example 1, the bearing bush material prepared by the components and the method of the embodiments 1-4 of the invention has better mechanical property, the sapphire fatigue limit can reach more than 190MPa, the hardness can reach more than 160HB, the yield strength can reach more than 280MPa, and the joint strength of the copper/steel interface can reach more than 300 MPa.

Comparative example 2

6 sets of parallel tests were designed, and the manufacturing process was the same as that of example 1 except that the line energy at the time of arc deposition in step (5) was 800, 1500, 2100, 2700, 3300, 3900, 4200J/cm, respectively, and the specific test results were shown in Table 2.

TABLE 2

As shown in table 2, the arc deposition line energy mainly affects the final shaping of the arch interface, when the line energy is too low, the arch shape is gentle, and when the line energy is too high, the arch shape is sharp, so the interface bonding strength is lower than 300MPa, and in order to achieve better interface bonding and improve the mechanical properties of the bearing bush material, the optimal line energy range is 900 to 4000J/cm.