阅读说明：本技术 一种高硬度硬质合金的焊接工艺 (Welding process of high-hardness hard alloy ) 是由 何平 于 2021-07-08 设计创作，主要内容包括：本发明提出了一种高硬度硬质合金的焊接工艺,涉及焊接技术领域。该高硬度硬质合金的焊接工艺包括如下步骤：将预处理后的合金片点焊在预处理后的钢件基体上,再经等离子粉末堆焊填充钢件基体和合金片之间的缝隙,所述粉末中包括碳化钨和镍,所述碳化钨的质量百分比为30％～60％,所述镍的质量百分比为40％～70％。本发明的优点在于,该焊接工艺可加工高硬度硬质合金,加工出来的工件基体和合金之间无缝隙,力学性能良好。(The invention provides a welding process of high-hardness hard alloy, and relates to the technical field of welding. The welding process of the high-hardness hard alloy comprises the following steps: the method comprises the following steps of spot welding a pretreated alloy sheet on a pretreated steel piece substrate, and filling a gap between the steel piece substrate and the alloy sheet through plasma powder surfacing, wherein the powder comprises 30-60% by mass of tungsten carbide and 40-70% by mass of nickel. The welding process has the advantages that the welding process can be used for processing high-hardness hard alloy, no gap exists between the processed workpiece matrix and the alloy, and the mechanical property is good.)

1. A welding process of high-hardness hard alloy comprises the following steps: the method comprises the following steps of spot welding a pretreated alloy sheet on a pretreated steel piece substrate, and filling a gap between the steel piece substrate and the alloy sheet through plasma powder surfacing, wherein the powder comprises 30-60% by mass of tungsten carbide and 40-70% by mass of nickel.

2. The welding process according to claim 1, wherein the spot welding is followed by heat preservation at 400-500 ℃ for 1-3 hours.

3. The welding process of claim 1, wherein the alloy sheet has a hardness HRA of 88 to 92 and a density of greater than 15.1g/cm³The bending strength is 52-57 Kg/mm²。

4. The welding process of claim 1, wherein the steel member base material comprises any one of ASTM4140, ASTM4145, 42CrMo, and 40 CrMo.

5. Welding process according to claim 1, characterized in that said pre-treatment comprises the following steps: cleaning the steel part matrix and the alloy with a cleaning agent until the steel part matrix and the alloy are soaked, obtaining the cleaned steel part matrix and the alloy, roughening the cleaned steel part matrix, obtaining a roughened steel part matrix, and carrying out spot welding on the roughened steel part matrix and the cleaned alloy within 2 hours after cleaning.

6. The welding process of claim 5, wherein the cleaning agent is ethanol or acetone.

7. The welding process of claim 5, wherein the material used for roughening is 10 mesh white corundum.

8. The welding process according to claim 1, 2 or 5, wherein the pressure of a welding machine used for spot welding is 5-10 MPa, a rolling bracket is used for fixing the steel piece base body during spot welding, and the contact time of the positive electrode and the negative electrode is set to be 1-3 seconds.

9. The welding process according to claim 8, wherein the current for plasma powder surfacing is 100-120A, the voltage is 36-40V, the powder feeding amount is 50-80 g/min, the protective pressure is 0.2-0.4 MPa, and the temperature of the matrix in the plasma surfacing process is 400-500 ℃.

10. The welding process according to claim 9, further comprising the following steps of after the plasma powder surfacing is completed, placing the workpiece into a resistance furnace, keeping the temperature for 8 hours at 300-400 ℃, naturally cooling the workpiece to room temperature, and then vibrating the workpiece up and down in a vibration disc for 0-6 min, wherein the vibration frequency is 40-60 times/min.

Technical Field

The invention relates to the technical field of welding, in particular to a welding process of high-hardness hard alloy.

Background

At present, workpieces in some special fields have high requirements on hardness or temperature. Taking the radial bearing of the down-hole screw drill tool used in the traditional manufacturing industry as an example, the radial bearing is generally prepared by adopting a sintering process at present. Common sintering equipment is a resistance furnace, a muffle furnace and the like, and the types of the common sintering equipment are divided into a bell-type electric furnace, a horizontal electric furnace and the like. Specifically, the YG8 hard alloy sheet with the specification of 15 × 15 × 3 or 20 × 6 × 3 or specially customized specification is pasted on a base steel piece by glue, the steel piece is sleeved by a die after the pasting, and a distance of about 1mm is left between the steel sleeve and the alloy so as to pour and sinter the required powder. And then, pouring the mixed tungsten carbide powder into the gap, wherein the closer the pouring is, the more the subsequent sintering quality is ensured. And then the filled radial bearing is placed into an electric furnace for sintering. The sintering process generally comprises the following steps: heating to 1050-1250 deg.c, maintaining for one hour, lowering the temperature step by step and taking out after the temperature inside the furnace is lowered to 100 deg.c. After sintering, subsequent processing is needed to be carried out, namely, the steel sleeve on the outer circle or the inner wall is turned off. If the welding process is used, the steel sleeve does not need to be turned off, so the processing cost of turning the steel sleeve is increased by the sintering process. In addition, the radial bearing produced by the sintering process and the welding process has great difference in quality and service life. The method comprises the following specific steps:

(1) because the sintering is not performed in a vacuum state, the metal oxidation is seriously damaged, and the mechanical property of the produced radial bearing is greatly influenced.

(2) During sintering, some refractory metals cannot be fully fused with the base steel part at 1050 ℃ to 1250 ℃, so that the difference between the produced radial bearing and the model is large.

(3) During sintering, the mixed powder contains certain oxygen which cannot be completely and effectively removed from the workpiece, so that the radial bearing has high porosity and poor compactness.

(4) The hardness of the matrix steel part is reduced at the sintering temperature of 1050-1250 ℃ and cannot reach HB310-330, certain quality hidden trouble exists, and the standard of the early-stage modulation process is reduced.

(5) The surface smoothness and the aesthetic degree of the prepared radial bearing are not enough, and compared with a welding process, the surface smoothness and the aesthetic degree of the prepared radial bearing have a difference visible to the naked eye.

At present, the service life of the radial bearing produced by the traditional sintering process at home and abroad is about 200-300 hours, and the service life of the bearing produced by the welding process can reach 500-700 hours. In addition to radial bearings, the oil industry downhole centralizers also currently suffer from certain processing deficiencies. At present, a cold setting process rather than a welding process is generally adopted for the drill collar centralizer to fix the hard alloy on the steel member substrate. The process has the defects that no filler exists between the matrix and the alloy, so the bonding force belongs to physical property, the welding process is metallurgical bonding, and the bonding effect is not in one grade. Secondly, the hardness difference between the base body and the alloy is too large (the base body is generally HRC45 or so, the alloy can reach HRA89), so that the base body is worn quickly under the condition that the alloy is not worn so much, the whole product fails, and the service life is short.

However, the hardness of the workpiece which cannot be processed by the current welding process is insufficient, and the over-hard material cannot be well welded by the common welding process, so that the requirement of the working environment cannot be met. Therefore, it is necessary to develop a welding process for high hardness cemented carbide.

Disclosure of Invention

The invention aims to provide a welding process of high-hardness hard alloy, which can be used for processing the high-hardness hard alloy, and the processed workpiece has no gap between the matrix and the alloy and has good mechanical property.

The technical problem to be solved by the invention is realized by adopting the following technical scheme.

The embodiment of the application provides a welding process of high-hardness hard alloy, which comprises the following steps: the method comprises the following steps of spot welding a pretreated alloy sheet on a pretreated steel piece substrate, and filling a gap between the steel piece substrate and the alloy sheet through plasma powder surfacing, wherein the powder comprises 30-60% by mass of tungsten carbide and 40-70% by mass of nickel.

Compared with the prior art, the embodiment of the invention has at least the following advantages or beneficial effects:

according to the invention, the alloy is firstly welded on the substrate by spot welding, and then specific powder is subjected to plasma powder surfacing, so that seamless connection between the alloy sheet and the substrate is realized, and the mechanical property of the prepared workpiece is improved. The welding process of the high-hardness hard alloy provided by the invention can be used for welding workpieces such as an upper radial bearing, a lower radial bearing, a wear-resistant sleeve, a drill collar centralizer and the like on a down-hole screw drill in the petroleum industry, can also be used for welding various wear-resistant plates, wear-resistant rods and the like in the mine industry, and can also be used for welding high-temperature dies special for high-temperature furnace mouths and the like with higher requirements on temperature in the steel industry.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a spot welding process in example 1 of the present invention;

FIG. 2 is a workpiece with the mold removed after completion of spot welding in example 1 of the present invention;

FIG. 3 is a plasma powder deposition process in example 1 of the present invention;

FIG. 4 is a workpiece after plasma powder deposition welding in example 1 of the present invention;

fig. 5 shows the radial bearing after finishing the refining in embodiment 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to specific examples.

The embodiment of the application provides a welding process of high-hardness hard alloy, which comprises the following steps: the method comprises the following steps of spot welding a pretreated alloy sheet on a pretreated steel piece substrate, and filling a gap between the steel piece substrate and the alloy sheet through plasma powder surfacing, wherein the powder comprises 30-60% by mass of tungsten carbide and 40-70% by mass of nickel.

In some embodiments of the invention, in the welding process, the temperature is kept at 400-500 ℃ for 1-3 hours after spot welding.

In some embodiments of the invention, in the welding process, the alloy sheet has a hardness HRA of 88-92 and a density of more than 15.1g/cm³The bending strength is 52-57 Kg/mm²。

In some embodiments of the present invention, in the welding process, the base material of the steel member includes any one of ASTM4140, ASTM4145, 42CrMo and 40 CrMo.

In some embodiments of the invention, in the welding process, the pretreatment comprises the following steps: cleaning the steel part matrix and the alloy with a cleaning agent until the steel part matrix and the alloy are soaked, obtaining the cleaned steel part matrix and the alloy, roughening the cleaned steel part matrix, obtaining a roughened steel part matrix, and carrying out spot welding on the roughened steel part matrix and the cleaned alloy within 2 hours after cleaning.

In some embodiments of the present invention, in the welding process, the cleaning agent is ethanol or acetone.

In some embodiments of the present invention, the material used for the roughening of the welding process is 10-mesh white corundum.

In some embodiments of the invention, in the welding process, the pressure of a welding machine used for spot welding is 5-10 mpa, a rolling bracket is used for fixing the steel member substrate during spot welding, and the contact time of the anode and the cathode of the electrode is set to be 1-3 seconds.

In some embodiments of the invention, in the welding process, the current for the plasma powder surfacing is 100-120A, the voltage is 36-40V, the powder feeding amount is 50-80 g/min, and the protective gas pressure is 0.2-0.4 Mpa; in order to prevent and reduce the occurrence of welding cracks, the temperature of the matrix in the plasma surfacing process is 400-500 ℃.

In some embodiments of the invention, in the welding process, after the plasma powder surfacing is completed, the method further comprises the following steps of putting the workpiece into a resistance furnace, keeping the temperature of the workpiece at 300-400 ℃ for 8 hours, naturally cooling the workpiece to room temperature, and then vibrating the workpiece in a vibration disc up and down for 0-6 min at a vibration frequency of 40-60 times/min.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The present embodiment aims to provide a welding process for a high-hardness cemented carbide, and the present embodiment takes the machining of a radial bearing as an example, and specifically includes the following steps:

1. material preparation

The steel part base material: american standard ASTM4140 or ASTM4145 can be used, and corresponding domestic brand 42CrMo or 40CrMo specific for downhole tools can also be used.

Alloy patch material: the temperature of the traditional sintering process is about 1050-1250 ℃, plasma welding is adopted in the embodiment, the arc flame temperature of plasma can reach 5000 ℃, and almost all refractory metals can be melted. Therefore, the material performance of the hard alloy patch of the welding process is far higher than that of the hard alloy patch of the traditional sintering process, so that the base body and the alloy can be fully welded together. Therefore, the HRA is 88 to 92, and the density is more than 15.1g/cm³The bending strength is 52-57 Kg/mm². The radial bearing welded by the alloy patch with the quality has no defects of cracks, holes, falling blocks or edge breakage and the like.

Welding powder materials: the powder of the welding process is also very different compared to the conventional sintering process. The traditional sintering process uses alloy powder (copper and a leaching alloy are used as main ingredients) with good self-fluxing property and low melting point as a filler, the powder used for welding in the embodiment is based on tungsten carbide, and also comprises nickel and other metals with high wear resistance, wherein the mass percent of the tungsten carbide is 30-60%, and the mass percent of the nickel is 40-70%.

2. Preparation before welding

The steel part substrate and the alloy are cleaned by ethanol or acetone, the cleaning time has no specific requirement, and the steel part substrate and the alloy are only required to be cleaned until the steel part substrate and the alloy are soaked and cleaned, but alloy spot welding is required to be carried out within 2 hours after cleaning. The surface of the substrate was roughened with 10 mesh white corundum by a pressure type sand blasting machine. The die is wrapped on the steel part by a metal wire and fixed. The die is carved by high-temperature resistant materials (polytetrafluoroethylene), and the flexibility is good.

3. Spot welding process

Labor and protective articles, especially goggles, must be worn before welding to prevent arc light from burning eyes, and an air draft circulating system must be started to ensure air flow in a workshop. Argon arc welding or resistance welding is selected according to different shapes of the alloy sheets. Removing impurities on the surface of the alloy sheet before spot welding, adjusting the pressure of a welding machine to 5-10 MPa, supporting a base body by using a rolling type bracket, setting the contact time of a positive electrode and a negative electrode of the electrode to be 1-3 seconds, and then welding the alloy sheet to the pit position of the typesetting mould one by one. After spot welding is finished, the metal wires are taken out, the die can be loosened naturally, and then the die and the substrate can be separated easily by hands. And putting the combination of the matrix and the alloy block into an electric furnace, heating to 400-500 ℃, and then preserving heat for 1-3 hours.

4. Plasma welding process

Filling welding powder into a powder feeding tank, and confirming the sealing property of the welding powder; the gas was checked for sufficiency (oxygen, acetylene and argon). And taking the spot-welded radial bearing out of the heat insulation box, visually confirming whether the alloy is complete or not and whether the condition of obvious block falling exists or not, and then placing the radial bearing on a plasma fusion welding machine for welding powder fillers. Plasma welding is a fully automated process, requiring only process parameters set prior to welding and close observation during welding. The welding process parameters of the radial bearing are as follows:

current: 100-120A, voltage: 36-40V, powder feeding and protective gas pressure (argon): 0.2-0.4 Mpa, powder feeding amount: and 50-80 g/min, wherein the stroke path of the welding gun is set according to the size of the radial bearing.

In order to prevent and reduce the occurrence of welding cracks, the temperature of the base body is ensured to be between 400 and 500 ℃ by combustion gas heat preservation in the welding process.

The following should also be noted during the welding process: stopping for 1 time every welding circle; if the emergency situation such as powder feeding blockage, ineffective protection after gas exhaustion and the like occurs, the emergency stop switch is required to be pressed in time to suspend operation. And starting welding after the fault is cleared.

After welding, the steel plate is put into a resistance furnace for heat preservation for 8 hours at the temperature of 300-400 ℃.

5. Post weld inspection

After welding, the workpiece is naturally cooled to room temperature, and then is placed in a vibration disc to vibrate for about 4-6 minutes, wherein the vibration frequency is 40-60 times per minute, and the mode is vertical vibration, so that the stress of the welded matrix is fully released, and the possibility of subsequent cracks is reduced. Then flaw detection is carried out to confirm whether the alloy has cracks or not and whether the filler has holes or not. And (4) performing inspection by dye check, uniformly spraying a red coloring agent on the surface of the workpiece, wiping the workpiece clean after 10 minutes, then spraying a developer, and observing whether the surface has red spots after 10 minutes. If no red spot appears, no crack, hole and other defects are shown.

6. Finish grinding

And finally processing the workpiece without the defects of cracks, cavities and the like after inspection, namely machining the workpiece to the size of the drawing according to the drawing, and obtaining the hard alloy radial bearing with high hardness.

Example 2

The present embodiment aims to provide a welding process for high-hardness cemented carbide, and the present embodiment takes the processing of a drill collar centralizer as an example, and specifically includes the following steps:

1. material preparation

The steel part base material: american standard ASTM4140 or ASTM4145 can be used, and corresponding domestic brand 42CrMo or 40CrMo specific for downhole tools can also be used.

Alloy patch material: the temperature of the traditional sintering process is about 1050-1250 ℃, plasma welding is adopted in the embodiment, the arc flame temperature of plasma can reach 5000 ℃, and almost all refractory metals can be melted. Therefore, the material performance of the hard alloy patch of the welding process is far higher than that of the hard alloy patch of the traditional sintering process, so that the base body and the alloy can be fully welded together. Therefore, the HRA is 88 to 92, and the density is more than 15.1g/cm³The bending strength is 52-57 Kg/mm². In the drill collar centralizer welded by the alloy patches with the quality, cracks, holes, falling blocks or the like can not occurEdge chipping and the like.

Welding powder materials: the powder of the welding process is also very different compared to the conventional sintering process. The traditional sintering process uses alloy powder (copper and a leaching alloy are used as main ingredients) with good self-fluxing property and low melting point as a filler, the powder used for welding in the embodiment is based on tungsten carbide, and also comprises nickel and other metals with high wear resistance, wherein the mass percent of the tungsten carbide is 30-60%, and the mass percent of the nickel is 40-70%.

2. Preparation before welding

The steel part substrate and the alloy are cleaned by ethanol or acetone, the cleaning time has no specific requirement, and the steel part substrate and the alloy are only required to be cleaned until the steel part substrate and the alloy are soaked and cleaned, but alloy spot welding is required to be carried out within 2 hours after cleaning. The surface of the substrate was roughened with 10 mesh white corundum by a pressure type sand blasting machine. The die is wrapped on the steel part by a metal wire and fixed. The die is carved by high-temperature resistant materials (polytetrafluoroethylene), and the flexibility is good.

3. Spot welding process

Labor and protective articles, especially goggles, must be worn before welding to prevent arc light from burning eyes, and an air draft circulating system must be started to ensure air flow in a workshop. Argon arc welding or resistance welding is selected according to different shapes of the alloy sheets. Removing impurities on the surface of the alloy sheet before spot welding, adjusting the pressure of a welding machine to 5-10 MPa, supporting a base body by using a rolling type bracket, setting the contact time of a positive electrode and a negative electrode of the electrode to be 1-3 seconds, and then welding the alloy sheet to the pit position of the typesetting mould one by one. After spot welding is finished, the metal wires are taken out, the die can be loosened naturally, and then the die and the substrate can be separated easily by hands. And putting the combination of the matrix and the alloy block into an electric furnace, heating to 400-500 ℃, and then preserving heat for 1-3 hours.

4. Plasma welding process

Filling welding powder into a powder feeding tank, and confirming the sealing property of the welding powder; the gas was checked for sufficiency (oxygen, acetylene and argon). And taking the drill collar centralizer after spot welding out of the heat insulation box, visually confirming whether the alloy is complete or not and whether the alloy obviously falls off or not, and then placing the drill collar centralizer on a plasma fusion welding machine for welding the powder filler. Plasma welding is a fully automated process, requiring only process parameters set prior to welding and close observation during welding. The welding technological parameters of the drill collar centralizer are as follows:

current: 100-120A, voltage: 36-40V, powder feeding and protective gas pressure (argon): 0.2-0.4 Mpa, powder feeding amount: and 50-80 g/min, wherein the travel path of the welding gun is set according to the size of the drill collar centralizer.

In order to prevent and reduce the occurrence of welding cracks, the temperature of the base body is ensured to be between 400 and 500 ℃ by combustion gas heat preservation in the welding process.

The following should also be noted during the welding process: stopping for 1 time every welding circle; if the emergency situation such as powder feeding blockage, ineffective protection after gas exhaustion and the like occurs, the emergency stop switch is required to be pressed in time to suspend operation. And starting welding after the fault is cleared.

After welding, the steel plate is put into a resistance furnace for heat preservation for 8 hours at the temperature of 300-400 ℃.

5. Post weld inspection

After welding, the workpiece is naturally cooled to room temperature, inspection is carried out by dye check, a red coloring agent is uniformly sprayed on the surface of the workpiece, after 10 minutes, the workpiece is wiped clean, then a developer is sprayed, and after 10 minutes, whether red spots exist on the surface is observed. If no red spot appears, no crack, hole and other defects are shown.

6. Finish grinding

And finally processing the workpiece without the defects of cracks, cavities and the like after inspection, namely machining the workpiece to the size of the drawing according to the drawing to obtain the hard alloy drill collar centralizer with high hardness.

Example 3

The present embodiment aims to provide a welding process for a high-hardness cemented carbide, and the present embodiment takes the machining of a wear-resistant sleeve as an example, and specifically includes the following steps:

1. material preparation

The steel part base material: american standard ASTM4140 or ASTM4145 can be used, and corresponding domestic brand 42CrMo or 40CrMo specific for downhole tools can also be used.

Alloy pasteSheet material: the temperature of the traditional sintering process is about 1050-1250 ℃, plasma welding is adopted in the embodiment, the arc flame temperature of plasma can reach 5000 ℃, and almost all refractory metals can be melted. Therefore, the material performance of the hard alloy patch of the welding process is far higher than that of the hard alloy patch of the traditional sintering process, so that the base body and the alloy can be fully welded together. Therefore, the HRA is 88 to 92, and the density is more than 15.1g/cm³The bending strength is 52-57 Kg/mm². The wear-resistant sleeve welded by the alloy patch with the quality has no defects of cracks, holes, falling blocks, edge breakage and the like.

Welding powder materials: the powder of the welding process is also very different compared to the conventional sintering process. The traditional sintering process uses alloy powder (copper and a leaching alloy are used as main ingredients) with good self-fluxing property and low melting point as a filler, the powder used for welding in the embodiment is based on tungsten carbide, and also comprises nickel and other metals with high wear resistance, wherein the mass percent of the tungsten carbide is 30-60%, and the mass percent of the nickel is 40-70%.

2. Preparation before welding

The steel part substrate and the alloy are cleaned by ethanol or acetone, the cleaning time has no specific requirement, and the steel part substrate and the alloy are only required to be cleaned until the steel part substrate and the alloy are soaked and cleaned, but alloy spot welding is required to be carried out within 2 hours after cleaning. The surface of the substrate was roughened with 10 mesh white corundum by a pressure type sand blasting machine. The die is wrapped on the steel part by a metal wire and fixed. The die is carved by high-temperature resistant materials (polytetrafluoroethylene), and the flexibility is good.

3. Spot welding process

Labor and protective articles, especially goggles, must be worn before welding to prevent arc light from burning eyes, and an air draft circulating system must be started to ensure air flow in a workshop. Argon arc welding or resistance welding is selected according to different shapes of the alloy sheets. Removing impurities on the surface of the alloy sheet before spot welding, adjusting the pressure of a welding machine to 5-10 MPa, supporting a base body by using a rolling type bracket, setting the contact time of a positive electrode and a negative electrode of the electrode to be 1-3 seconds, and then welding the alloy sheet to the pit position of the typesetting mould one by one. After spot welding is finished, the metal wires are taken out, the die can be loosened naturally, and then the die and the substrate can be separated easily by hands. And putting the combination of the matrix and the alloy block into an electric furnace, heating to 400-500 ℃, and then preserving heat for 1-3 hours.

4. Plasma welding process

Filling welding powder into a powder feeding tank, and confirming the sealing property of the welding powder; the gas was checked for sufficiency (oxygen, acetylene and argon). And taking the spot-welded wear-resistant sleeve out of the heat insulation box, visually confirming whether the alloy is complete or not and whether the alloy obviously falls off or not, and then placing the wear-resistant sleeve on a plasma fusion welding machine for welding the powder filler. Plasma welding is a fully automated process, requiring only process parameters set prior to welding and close observation during welding. The welding technological parameters of the wear-resistant sleeve are as follows:

current: 100-120A, voltage: 36-40V, 0.2-0.4 Mpa of powder feeding and protective pressure (argon), 50-80 g/min of powder feeding amount, and the stroke path of the welding gun is set according to the size of the wear-resistant sleeve.

In order to prevent and reduce the occurrence of welding cracks, the temperature of the base body is ensured to be between 400 and 500 ℃ by combustion gas heat preservation in the welding process.

The following should also be noted during the welding process: stopping for 1 time every welding circle; if the emergency situation such as powder feeding blockage, ineffective protection after gas exhaustion and the like occurs, the emergency stop switch is required to be pressed in time to suspend operation. And starting welding after the fault is cleared.

After welding, the steel plate is put into a resistance furnace for heat preservation for 8 hours at the temperature of 300-400 ℃.

5. Post weld inspection

After welding, the workpiece is naturally cooled to room temperature, and then is placed in a vibration disc to vibrate for about 4-6 minutes, wherein the vibration frequency is 40-60 times per minute, and the mode is vertical vibration, so that the stress of the welded matrix is fully released, and the possibility of subsequent cracks is reduced. Then flaw detection is carried out to confirm whether the alloy has cracks or not and whether the filler has holes or not. And (4) performing inspection by dye check, uniformly spraying a red coloring agent on the surface of the workpiece, wiping the workpiece clean after 10 minutes, then spraying a developer, and observing whether the surface has red spots after 10 minutes. If no red spot appears, no crack, hole and other defects are shown.

6. Finish grinding

And finally processing the workpiece without the defects of cracks, cavities and the like after inspection, namely machining the workpiece to the size of the drawing according to the drawing to obtain the hard alloy wear-resistant sleeve with high hardness.

Examples of effects

The purpose of this effect example is to verify the performance of the workpiece produced by the welding process of the high hardness cemented carbide provided in the foregoing examples.

1. Test group parameters

The respective groups of workpieces were prepared according to the preparation methods described in examples 1 to 3, with the parameters shown in table 1. The parameters are shown in table 1:

TABLE 1

2. Performance of the workpieces in each test set

Corresponding performance measurements were carried out according to the parameters shown in Table 2, the criteria and results are shown in the following table:

TABLE 2

As can be seen from the table above, the performance of the workpiece obtained in each test example (test examples 1, 2 and 3) of the radial bearing, the drill collar centralizer and the wear-resistant sleeve is better and far higher than that of the workpiece prepared by the traditional sintering process, and the average range of various performance parameters of the workpiece prepared by the novel welding process provided by the application can be reached.

In summary, the welding process for the high-hardness cemented carbide provided by the embodiment of the invention has the following advantages:

plasma powder welding is a surface treatment process which takes plasma arcs as a heat source, applies high temperature generated by the plasma arcs, rapidly heats alloy powder to the surface of gas, simultaneously melts, mixes, diffuses, solidifies and is qualified after ion beams leave, forms a high-performance alloy layer and realizes the surface strengthening and hardening of parts. The plasma arc has good arc temperature, thermal conductivity and stability, so that the melt depth can be adjusted, and after the plasma powder is subjected to surface treatment, a fusion interface is formed between a gas material and a surface material, so that the bonding strength is high. The surface layer has compact structure, corrosion resistance and good wear resistance. The gas material and the surface material are less diluted, and the change of the material characteristics is small. According to the invention, the alloy is firstly welded on the substrate by spot welding, and then specific powder is subjected to plasma powder surfacing, so that seamless connection between the alloy sheet and the substrate is realized, and the mechanical property of the prepared workpiece is improved.

The welding process of the high-hardness hard alloy provided by the invention can be used for welding workpieces such as an upper radial bearing, a lower radial bearing, a wear-resistant sleeve, a drill collar centralizer and the like on a down-hole screw drill in the petroleum industry, can also be used for welding various wear-resistant plates and wear-resistant rods in the mine industry, and can also be used for welding high-temperature dies special for high-temperature furnace mouths and the like with higher requirements on temperature in the steel industry.

In addition, it should be noted that in addition to the base material used in the test examples, 40CrMo can be used to prepare various types of workpieces.

The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. 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.