Method for preparing copper-steel composite rod at low cost through vacuum hot pressing furnace

Abstract

The invention discloses a method for preparing a copper-steel composite rod at low cost through a vacuum hot pressing furnace, which comprises the following steps: processing a plurality of graphite holes in a graphite plate, assembling a stainless steel pipe and a copper rod in each graphite hole, carrying out vacuum hot pressing welding, and cooling to obtain the copper-steel composite rod; the stainless steel pipe is placed in the graphite hole, the copper bar is placed in the stainless steel pipe, a guide column with the same diameter as the copper bar is placed at the top end of the copper bar, and the guide column coincides with the axis of the copper bar. According to the method, the graphite plate with the multiple graphite holes is adopted, the stainless steel pipe and the copper rod are assembled into the graphite holes, then the stainless steel pipe and the copper rod are connected through vacuum thermocompression welding, the copper-steel composite rod stable in quality is obtained, large-batch and low-cost preparation of the copper-steel composite rod can be achieved, and the production cost is reduced. The method is suitable for preparing copper-steel composite rods required in the fields of military industry, petroleum, aerospace, marine industry, nuclear industry and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite rod preparation, and particularly relates to a method for preparing copper-steel composite rods at low cost through a vacuum hot-pressing furnace. BACKGROUND

[0002] Explosion welding is an advanced solid-state welding technology, which uses high pressure generated by explosive detonation as energy to realize the metallurgical bonding between the metals to be welded. The explosion welding technology has the characteristics of realizing high-quality welding between heterogeneous metals, manufacturing various metal composite materials with wide application, high welding strength and low welding cost. Therefore, the explosion welding technology is increasingly widely applied in the manufacturing field. In recent years, the composite metal pipes or rods manufactured by using the explosion welding technology have been widely applied in the fields of military industry, petroleum, aerospace, marine industry and nuclear industry.

[0003] However, the explosion welding of the composite rods has the following technical problems: 1) due to the limitation of the process itself, the wall thickness of the steel pipe is generally not more than 5 mm; 2) due to the limitation of the principle of the explosion welding itself, the copper rod can only be an equal-diameter copper rod; 3) the length of the rod is limited by the process, and the longer the length is, the more unstable the interface quality is, and the explosion welding is difficult to realize when the length exceeds 120 mm; 4) the explosion welding of the composite rods is carried out one by one, and artificial explosive distribution is required before each explosion of the composite rods, the product quality is unstable, the product qualification rate is greatly affected by the manual operation, the production cycle is affected by the natural environment such as weather, and the cost is higher; 5) the explosion welding needs to use flammable and explosive materials such as explosives and detonators, and the explosion welding process produces toxic and harmful substances such as sound waves and smoke to pollute the environment. SUMMARY

[0004] The present application aims at overcoming the above-mentioned deficiencies in the prior art, and provides a method for preparing copper-steel composite rods at low cost through a vacuum hot-pressing furnace. The method assembles the stainless steel pipe and the copper rod into the graphite hole by using the graphite plate with a plurality of graphite holes, and then connects the stainless steel pipe and the copper rod by using vacuum hot-pressing welding to obtain the copper-steel composite rods with stable quality. The method can be used for mass production of the copper-steel composite rods, and solves the problems of low qualification rate and difficulty in mass production of the copper-steel composite rods prepared by using the explosion welding.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a method for preparing copper-steel composite rods at low cost through a vacuum hot-pressing furnace, which comprises the following steps: machining a plurality of graphite holes on a graphite plate, assembling the stainless steel pipe and the copper rod in each graphite hole, and then performing vacuum hot-pressing welding to obtain the copper-steel composite rods after cooling; the assembling comprises the following steps: placing the stainless steel pipe into the graphite hole, placing the copper rod into the stainless steel pipe, and placing a guide column with the same diameter as the copper rod on the top end of the copper rod, wherein the guide column is coaxial with the axis of the copper rod.

[0006] The application places a guide column with the same diameter as the copper rod on the top of the copper rod to control the pressure in the vacuum hot pressing, only the copper rod is applied, since the melting point of oxygen-free copper is 1083 DEG C, when the temperature is 920 DEG C ~ 930 DEG C, the copper rod is extremely soft and obvious volume expansion occurs, the pressure applied to the copper rod can avoid the copper rod extending upward and force the copper rod to expand along the radial direction, the copper rod and the steel pipe are completely attached and there is a certain pressure stress, which can provide conditions for the sufficient diffusion of copper and iron atoms.

[0007] The method for preparing the copper-steel composite rod at low cost through the vacuum hot pressing furnace, the stainless steel pipe and the copper rod are ultrasonically cleaned with ethanol as the medium before being assembled.

[0008] The method for preparing the copper-steel composite rod at low cost through the vacuum hot pressing furnace, the gap between the stainless steel pipe and the copper rod after being assembled and the gap between the stainless steel pipe and the graphite hole are 0.05mm~0.1mm, and the height of the stainless steel pipe and the copper rod is lower than the depth of the graphite hole by 5mm~10mm.

[0009] Although the volume expansion of the copper rod at high temperature is large, it is limited, and a certain pressure stress needs to be maintained between the copper rod and the steel pipe after the gap is filled, so as to ensure that sufficient atomic diffusion occurs at the copper-steel interface, and insufficient pressure stress will cause hole defects at the copper-steel interface, affecting the interface bonding quality; therefore, the gap between the stainless steel pipe and the copper rod is controlled to be 0.05mm~0.1mm, the gap is as small as possible under the premise of ensuring assembly, so as to ensure that sufficient atomic diffusion occurs at the copper-steel interface.

[0010] The method for preparing the copper-steel composite rod at low cost through the vacuum hot pressing furnace, the height of the guide column protruding from the graphite hole is 5mm~10mm.

[0011] The method for preparing the copper-steel composite rod at low cost through the vacuum hot pressing furnace, a fixing ring for fixing the horizontal position of the guide column is arranged on the outer sleeve of the guide column, and the material of the guide column is graphite or molybdenum.

[0012] The method for preparing the copper-steel composite rod at low cost through the vacuum hot pressing furnace, the material of the fixing ring is graphite or molybdenum.

[0013] The method for preparing the copper-steel composite rod at low cost through the vacuum hot pressing furnace, in an environment with a vacuum degree of 10 -3 Pa or below, the temperature is raised to 650 DEG C ~ 700 DEG C at a rate of 1 DEG C / min ~ 10 DEG C / min and kept for 30min~60min, and the pressure of 3MPa is applied to the guide column by the pressure head of the vacuum hot pressing furnace at a rate of 0.1mm / min~0.5mm / min after the temperature is raised to 650 DEG C ~ 700 DEG C. Then, the temperature is increased at a rate of 5℃ / min~10℃ / min to 920℃~930℃ and kept for 120min or more, while a pressure of 7MPa~10MPa is applied to the guide column at a rate of 0.1mm / min~0.5mm / min after the temperature is increased to 920℃~930℃, and then the copper-steel composite rod is obtained by cooling to 200℃ and then discharging from the furnace and air cooling.

[0014] Compared with the prior art, the present application has the following advantages: 1. The copper-steel composite rod can be mass-produced by vacuum hot pressing welding, and different specifications of copper-steel composite rods can be prepared by adjusting the size of the graphite hole. Compared with explosive welding, the interface quality of the copper-steel composite rod with a diameter of 120mm or more prepared by the method of the present application is stable, and the preparation process is green and environmentally friendly, without producing toxic and harmful substances such as sound waves and smoke to pollute the environment.

[0015] 2. The method of the present application enables the copper and stainless steel to diffuse at high temperature, realizes the combination of the stainless steel pipe and the copper rod, and avoids the difficulty of filler filling when using non-equivalent diameter copper rods as raw materials.

[0016] 3. The copper-steel composite rod prepared by the method of the present application has excellent interface quality and high yield, and the UT flaw detection (ultrasonic flaw detection) of the copper-steel composite rod prepared by the method of the present application is 100% combined, and the interface compression shear strength is 160MPa~180MPa.

[0017] The technical solutions of the present application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a structure diagram of the graphite plate of the present application.

[0019] Figure 2 The figure is a cross-sectional structure diagram of the stainless steel pipe and the copper rod after assembly in Example 1 of the present application.

[0020] Figure 3 The figure is a physical diagram of the copper-steel composite rod prepared in Example 1 of the present application.

[0021] Figure 4 The figure is a cross-sectional structure diagram of the stainless steel pipe and the copper rod after assembly in Example 2 of the present application.

[0022] Figure 5This is a physical picture of the copper-steel composite rod prepared in Example 2 of the present invention.

[0023] Reference numerals: 1—graphite plate; 2—graphite hole; 3—stainless steel tube; 4—copper rod; 5—guide column; 6—fixing ring. DETAILED DESCRIPTION

[0024] Example 1 The method for preparing the copper-steel composite rod in this embodiment is as follows: a plurality of graphite holes 2 (such as Figure 1 As shown), the stainless steel tube 3 and the copper rod 4 are ultrasonically cleaned with ethanol as a medium, and then the stainless steel tube 3 and the copper rod 4 are assembled in each graphite hole 2, and then vacuum hot-pressed; the outer diameter of the stainless steel tube 3 is 120 mm, and the diameter of the copper rod 4 is 65 mm; like Figure 2 As shown, the assembly is as follows: the stainless steel tube 3 is placed in the graphite hole 2, the copper rod 4 is placed in the stainless steel tube 3, the gap between the stainless steel tube 3 and the copper rod 4, and the gap between the stainless steel tube 3 and the graphite hole 2 are controlled to be 0.05mm~0.1mm, and a guide post 5 with the same diameter as the copper rod 4 is placed on the top of the copper rod 4, and the height of the guide post 5 protruding from the graphite hole 2 is 5mm~10mm; then a fixing ring 6 is arranged on the outer surface of the guide post 5, and the fixing ring 6 is clamped between the guide post 5 and the graphite hole 2 to prevent the guide post 5 from moving in the horizontal direction; the guide post 5 and the fixing ring 6 are both made of graphite or molybdenum; The vacuum hot press furnace was evacuated to 10 -3 Pa, the temperature was raised to 700°C at a rate of 10°C / min and kept for 30 minutes, and at the same time, after the temperature was raised to 700°C, a pressure of 3 MPa was slowly applied to the guide pillar 5 by the pressure head of the vacuum hot pressing furnace; then the temperature was raised to 920°C at a rate of 10°C / min and kept for 120 minutes, and at the same time, after the temperature was raised to 920°C, a pressure of 9 MPa was slowly applied to the guide pillar 5, and then the product was cooled to 200°C and taken out of the furnace. After air cooling, the product was obtained as shown in FIG. Figure 3 Copper-steel composite rod shown.

[0025] The copper-steel composite rod prepared in this embodiment is as follows Figure 3 As shown, the surface is intact and the bonding is good. UT testing shows 100% bonding, and the interface compressive shear strength is between 160MPa and 180MPa.

[0026] Example 2 The method for preparing the copper-steel composite rod in this embodiment is as follows: a plurality of graphite holes 2 (such as Figure 1As shown in FIG. 1, the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are ultrasonically cleaned in ethanol as a medium, and then the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are assembled in each graphite hole 2 and then vacuum hot-press welded; the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are assembled with a gap fit; the non-equal-diameter copper rod 4 is composed of a large cylinder and a small cylinder, wherein the large cylinder has a diameter of 65 mm and the small cylinder has a diameter of 50 mm; the non-equal-diameter stainless steel pipe 3 has an equal outer diameter of 120 mm at each height; As shown in FIG. 1, the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are ultrasonically cleaned in ethanol as a medium, and then the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are assembled in each graphite hole 2 and then vacuum hot-press welded; the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are assembled with a gap fit; the non-equal-diameter copper rod 4 is composed of a large cylinder and a small cylinder, wherein the large cylinder has a diameter of 65 mm and the small cylinder has a diameter of 50 mm; the non-equal-diameter stainless steel pipe 3 has an equal outer diameter of 120 mm at each height; Figure 4 As shown in FIG. 1, the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are ultrasonically cleaned in ethanol as a medium, and then the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are assembled in each graphite hole 2 and then vacuum hot-press welded; the non-equal-diameter stainless steel pipe 3 and the non-equal-diameter copper rod 4 are assembled with a gap fit; the non-equal-diameter copper rod 4 is composed of a large cylinder and a small cylinder, wherein the large cylinder has a diameter of 65 mm and the small cylinder has a diameter of 50 mm; the non-equal-diameter stainless steel pipe 3 has an equal outer diameter of 120 mm at each height; The vacuum hot-pressing furnace is vacuumed to 10 -3 Pa or below, heated to 650℃ at a rate of 1℃ / min and kept for 60 min, and at the same time, the guide column 5 is slowly pressed to 3 MPa by the pressure head of the vacuum hot-pressing furnace after being heated to 650℃, then heated to 930℃ at a rate of 5℃ / min and kept for 120 min, and at the same time, the guide column 5 is slowly pressed to 10 MPa after being heated to 930℃, and then cooled to 200℃ and discharged from the furnace, and the copper-steel composite rod as shown in FIG. 2 is obtained after air cooling. Figure 5 The copper-steel composite rod prepared in this embodiment is as shown in FIG. 2, which is not damaged on the outer surface, has good bonding, and has 100% bonding after UT detection, and the interface compression shear strength is between 160 MPa and 180 MPa.

[0027] The copper-steel composite rod prepared in this embodiment is as shown in FIG. 2, which is not damaged on the outer surface, has good bonding, and has 100% bonding after UT detection, and the interface compression shear strength is between 160 MPa and 180 MPa. Figure 5 The copper-steel composite rod prepared in this embodiment is as shown in FIG. 2, which is not damaged on the outer surface, has good bonding, and has 100% bonding after UT detection, and the interface compression shear strength is between 160 MPa and 180 MPa.

[0028] Example 3 The difference between this embodiment and Example 1 is that the vacuum hot-pressing furnace is vacuumed to 10 -3 Pa or below, heated to 680℃ at a rate of 5℃ / min and kept for 40 min, and at the same time, the guide column 5 is slowly pressed to 3 MPa by the pressure head of the vacuum hot-pressing furnace after being heated to 680℃, then heated to 925℃ at a rate of 8℃ / min and kept for 120 min, and at the same time, the guide column 5 is slowly pressed to 7 MPa after being heated to 925℃, and then cooled to 200℃ and discharged from the furnace, and the copper-steel composite rod is obtained after air cooling.

[0029] The copper-steel composite rod prepared in the embodiment has no damage on the outer surface, good combination, 100% combination after UT detection, and the interface compression shear strength is between 160 MPa and 180 MPa.

[0030] The above is only the preferred embodiment of the present application, and does not limit the present application. Any simple modification, change and equivalent structure change of the above embodiment according to the technical essence of the present application are still within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing copper-steel composite rods at low cost by using a vacuum hot pressing furnace, characterized in that: A plurality of graphite holes (2) are machined on a graphite plate (1), a stainless steel tube (3) and a copper rod (4) are assembled in each graphite hole (2), vacuum hot pressing welding is performed, and a copper-steel composite rod is obtained after cooling; the assembly comprises placing the stainless steel tube (3) into the graphite hole (2), placing the copper rod (4) into the stainless steel tube (3), and placing a guide column (5) having the same diameter as the copper rod (4) at the top end of the copper rod (4), wherein the guide column (5) coincides with the axis of the copper rod (4).

2. The method for preparing copper-steel composite rods at low cost by using a vacuum hot pressing furnace according to claim 1, characterized in that: The stainless steel tube (3) and the copper rod (4) are ultrasonically cleaned using ethanol as a medium before assembly.

3. The method for preparing copper-steel composite rods at low cost by using a vacuum hot pressing furnace according to claim 1, characterized in that: After assembly, the gap between the stainless steel tube (3) and the copper rod (4), and the gap between the stainless steel tube (3) and the graphite hole (2) are both 0.05 mm to 0.1 mm, and the height of the stainless steel tube (3) and the copper rod (4) is 5 mm to 10 mm lower than the depth of the graphite hole (2).

4. The method for preparing copper-steel composite rods at low cost by using a vacuum hot pressing furnace according to claim 1, wherein: The height of the guide pillar (5) protruding from the graphite hole (2) is 5 mm to 10 mm.

5. The method for preparing copper-steel composite rods at low cost by using a vacuum hot pressing furnace according to claim 1, characterized in that: The outer sleeve of the guide post (5) is provided with a fixing ring (6) for fixing the horizontal position of the guide post (5), and the material of the guide post (5) is graphite or molybdenum.

6. The method for preparing copper-steel composite rods at low cost by using a vacuum hot pressing furnace according to claim 5, characterized in that: The material of the fixing ring (6) is graphite or molybdenum.

7. The method for preparing copper-steel composite rods at low cost by using a vacuum hot pressing furnace according to claim 1, characterized in that: The vacuum hot pressing welding method is as follows: -3 In an environment below Pa, the temperature is raised to 650°C~700°C at a rate of 1°C / min~10°C / min and kept at this temperature for 30min~60min. At the same time, after the temperature is raised to 650°C~700°C, a pressure of 0.1mm / min~0.5mm / min is applied to the guide pillar (5) by the pressure head of the vacuum hot pressing furnace to a pressure of 3MPa; Then, the temperature is raised to 920°C~930°C at a rate of 5°C / min~10°C / min and kept at this temperature for more than 120 minutes. At the same time, after the temperature is raised to 920°C~930°C, a pressure of 7MPa~10MPa is applied to the guide pillar (5) at a rate of 0.1mm / min~0.5mm / min. The copper-steel composite rod is then cooled to 200°C and taken out of the furnace and air-cooled to obtain the copper-steel composite rod.

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