A method for low cost production of copper-steel composite rods by vacuum hot pressing furnace

Abstract

The application discloses a method for preparing copper-steel composite rods at low cost through a vacuum hot pressing furnace, a plurality of graphite holes are processed on a graphite plate, a stainless steel pipe and a copper rod are assembled in each graphite hole, vacuum hot pressing welding is carried out, and a copper-steel composite rod is obtained after cooling; the assembly is that the stainless steel pipe is placed into the graphite hole, the copper rod is placed into the stainless steel pipe, and a guide column with the same diameter as the copper rod is placed at the top end of the copper rod, and the guide column is coaxial with the axis of the copper rod. The method is characterized in that the graphite plate with a plurality of graphite holes is adopted, the stainless steel pipe and the copper rod are assembled into the graphite hole, then the stainless steel pipe and the copper rod are connected through vacuum hot pressing welding, the copper-steel composite rod with stable quality is obtained, the copper-steel composite rod can be prepared in large quantities and at low cost, and the copper-steel composite rod is suitable for preparing copper-steel composite rods required in the fields of military industry, petroleum industry, aerospace industry, ocean industry and nuclear industry.

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, which is only applied to the copper rod, since the melting point of oxygen-free copper is 1083 DEG C, when the temperature is 920 DEG C to 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 is completely attached to the steel pipe and a certain pressure stress exists, 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 to 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 to 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 the copper-steel interface will have hole defects and affect the interface bonding quality if the pressure stress is insufficient, therefore, the gap between the stainless steel pipe and the copper rod is controlled to be 0.05mm to 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 to 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 to 700 DEG C at a rate of 1 DEG C / min to 10 DEG C / min and kept for 30min to 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 to 0.5mm / min after the temperature is raised to 650 DEG C to 700 DEG C.

[0014] 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 taken out of the furnace and air-cooled.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. The present application can mass-produce copper-steel composite rods by vacuum hot pressing welding, and different specifications of copper-steel composite rods can be prepared by adjusting the size of the graphite hole.

[0017] 2. The present application can realize the combination of the stainless steel pipe and the copper rod by making the copper and stainless steel materials diffuse unlimitedly at high temperature through vacuum hot pressing welding.

[0018] 3. The present application can obtain copper-steel composite rods with excellent interface quality and high yield by limiting the axial expansion of the copper rod at high temperature, forcing the copper rod to expand radially, utilizing the radial expansion of copper to realize the atomic diffusion between the copper-steel interface at high temperature and high pressure, and performing vacuum hot pressing welding in stages.

[0019] The technical solutions of the present application will be further described in detail below with the aid of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a structure diagram of the graphite plate of the present application.

[0021] Figure 2 It is a cross-sectional structure diagram of the assembled stainless steel pipe and copper rod in Example 1 of the present application.

[0022] Figure 3 It is a physical diagram of the copper-steel composite rod prepared in Example 1 of the present application.

[0023] Figure 4 It is a cross-sectional structure diagram of the assembled stainless steel pipe and copper rod in Example 2 of the present application.

[0024] Figure 5A physical diagram of the copper-steel composite rod prepared in Example 2 of the present application.

[0025] Reference signs:

[0026] 1 - graphite plate; 2 - graphite hole; 3 - stainless steel tube; 4 - copper rod; 5 - guide column; 6 - fixing ring. DETAILED DESCRIPTION

[0027] Example 1

[0028] The method for preparing the copper-steel composite rod in this example is as follows: a plurality of graphite holes 2 (as shown in Figure 1 ) are machined on a graphite plate 1, the stainless steel tube 3 and the copper rod 4 are ultrasonically cleaned with ethanol as the medium, then the stainless steel tube 3 and the copper rod 4 are assembled in each graphite hole 2, and vacuum hot pressing welding is performed; the outer diameter of the stainless steel tube 3 is 120 mm, and the diameter of the copper rod 4 is 65 mm;

[0029] As shown in Figure 2 , the assembly is as follows: the stainless steel tube 3 is placed into the graphite hole 2, the copper rod 4 is placed into 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 both controlled to be 0.05 mm to 0.1 mm, and a guide column 5 with the same diameter as the copper rod 4 is placed on the top end of the copper rod 4, and the height of the guide column 5 protruding from the graphite hole 2 is 5 mm to 10 mm; then a fixing ring 6 is provided outside the guide column 5, the fixing ring 6 is clamped between the guide column 5 and the graphite hole 2 to prevent the guide column 5 from moving in the horizontal direction; the materials of the guide column 5 and the fixing ring 6 are both graphite or molybdenum;

[0030] The vacuum hot pressing furnace is pumped to a vacuum of 10 -3 Pa or less, heated to 700℃ at a rate of 10℃ / min and kept for 30 min, and at the same time, a slow pressure of 3 MPa is applied to the guide column 5 through the pressure head of the vacuum hot pressing furnace after heating to 700℃; then heated to 920℃ at a rate of 10℃ / min and kept for 120 min, and at the same time, a slow pressure of 9 MPa is applied to the guide column 5 after heating to 920℃, then cooled to 200℃ and taken out of the furnace, and after air cooling, the copper-steel composite rod as shown in Figure 3 is obtained.

[0031] The copper-steel composite rod prepared in this example is as shown in Figure 3 , which is intact in appearance and well combined, the UT flaw detection is 100% combined, and the interface compression shear strength is between 160 MPa and 180 MPa.

[0032] Example 2

[0033] The method for preparing the copper-steel composite rod in this example is as follows: a plurality of graphite holes 2 (as shown in Figure 1As shown, the non-equal diameter stainless steel tube 3 and the non-equal diameter copper rod 4 are ultrasonically cleaned with ethanol as the medium. Then, the non-equal diameter stainless steel tube 3 and the non-equal diameter copper rod 4 are assembled in each graphite hole 2 and then vacuum hot-pressed welded. The non-equal diameter stainless steel tube 3 and the non-equal diameter copper rod 4 are fitted with a clearance after assembly. The non-equal diameter copper rod 4 is composed of a large cylinder and a small cylinder, wherein the diameter of the large cylinder is 65mm and the diameter of the small cylinder is 50mm. The outer diameter of the non-equal diameter stainless steel tube 3 is 120mm, which is the same at all heights.

[0034] like Figure 4 As shown, the assembly involves placing a non-uniform diameter stainless steel tube 3 into a graphite hole 2, and a non-uniform diameter copper rod 4 into the stainless steel tube 3. The gaps between the non-uniform diameter stainless steel tube 3 and the non-uniform diameter copper rod 4, and between the non-uniform diameter stainless steel tube 3 and the graphite hole 2, are controlled to be 0.05mm~0.1mm. A guide post 5 with the same diameter as the non-uniform diameter copper rod 4 is placed at the top of the non-uniform diameter copper rod 4. The axis of the guide post 5 coincides with that of the non-uniform diameter 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 fitted over the guide post 5, which is engaged between the guide post 5 and the graphite hole 2 to prevent the guide post 5 from moving horizontally. Both the guide post 5 and the fixing ring 6 are made of graphite or molybdenum.

[0035] Evacuate the vacuum hot press furnace to 10°C. -3 Below Pa, the temperature is increased to 650℃ at a rate of 1℃ / min and held for 60 min. Simultaneously, after reaching 650℃, a pressure of 3 MPa is slowly applied to the guide column 5 through the pressure head of a vacuum hot press furnace. Then, the temperature is increased to 930℃ at a rate of 5℃ / min and held for 120 min. Simultaneously, after reaching 930℃, a pressure of 10 MPa is slowly applied to the guide column 5. The column is then cooled to 200℃ and removed from the furnace. After air cooling, the desired result is obtained as shown below. Figure 5 The copper-steel composite rod shown.

[0036] The copper-steel composite rod prepared in this embodiment is as follows: Figure 5 As shown, the surface is undamaged, the bond is good, and the UT test shows 100% bonding. The interfacial compressive and shear strength is between 160MPa and 180MPa.

[0037] Example 3

[0038] The difference between this embodiment and Embodiment 1 is that the vacuum hot press furnace is evacuated to 10... -3Pa or below, the temperature is increased to 680℃ at a rate of 5℃ / min, and the guide column 5 is slowly pressed to 3MPa by the vacuum hot press furnace pressure head after the temperature is increased to 680℃; then the temperature is increased to 925℃ at a rate of 8℃ / min, and the guide column 5 is slowly pressed to 7MPa after the temperature is increased to 925℃, and then the furnace is cooled to 200℃, and then the copper-steel composite rod is obtained after air cooling.

[0039] 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 160MPa and 180MPa.

[0040] The above is only a preferred embodiment of the present application, and does not limit the present application, and 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 low cost production of copper-steel composite rods by vacuum hot pressing furnace, characterized by, By machining a plurality of graphite holes (2) on a graphite plate (1), assembling a stainless steel pipe (3) and a copper rod (4) in each graphite hole (2), and then performing vacuum hot-press welding, a copper-steel composite rod is obtained after cooling; the assembling is placing the stainless steel pipe (3) into the graphite hole (2), placing the copper rod (4) into the stainless steel pipe (3), and placing a guide column (5) with the same diameter as the copper rod (4) on the top end of the copper rod (4), the guide column (5) is coaxial with the copper rod (4); the gap between the stainless steel pipe (3) and the copper rod (4) after the assembling is 0.05mm~0.1mm, the gap between the stainless steel pipe (3) and the graphite hole (2) is 0.05mm~0.1mm, the height of the stainless steel pipe (3) and the copper rod (4) is lower than the depth of the graphite hole (2) by 5mm~10mm, and the height of the guide column (5) protruding from the graphite hole (2) is 5mm~10mm; The method of vacuum hot press welding is to heat to 650-700℃ at a rate of 1-10℃ / min in an environment with a vacuum degree of 10 -3 In an environment with a pressure of 0.1-0.5MPa, the temperature is raised to 650-700℃ at a rate of 1-10℃ / min, and the pressure is applied to the guide column (5) at a rate of 0.1-0.5mm / min to 3MPa by the pressure head of the vacuum hot press furnace after the temperature is raised to 650-700℃. then heating at a rate of 5℃ / min~10℃ / min to 920℃~930℃ and keeping for 120min or more, while applying a pressure of 7MPa~10MPa to the guide column (5) at a rate of 0.1mm / min~0.5mm / min after heating to 920℃~930℃, and then cooling to 200℃ and discharging from the furnace, and air cooling to obtain the copper-steel composite rod.

2. A method of low cost production of copper-steel composite rods by vacuum hot pressing furnace as claimed in claim 1 wherein, The stainless steel pipe (3) and the copper rod (4) are ultrasonically cleaned with ethanol as the medium before assembling.

3. A method of low cost production of copper-steel composite rods by vacuum hot pressing furnace as claimed in claim 1 wherein, The guide column (5) is provided with a fixing ring (6) for fixing the horizontal position of the guide column (5), and the material of the guide column (5) is graphite or molybdenum.

4. A method of low cost production of copper-steel composite rods by vacuum hot pressing furnace as claimed in claim 3 wherein, The material of the fixing ring (6) is graphite or molybdenum.

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