Method for pulsed current assisted rolling of double-layered titanium steel clad plate

Abstract

The application discloses a method for pulsed current assisted rolling of double-layer composite thick titanium steel plate, which comprises the following steps: corrugated roller rolling, the steel plate is rolled by additional pulsed current, the corrugated morphology is formed on the surface of the steel plate, and local strong force is formed on the corrugated surface; a large pulsed electron beam is used to treat the composite surface of the steel plate and the titanium plate; the steel plate and the titanium plate are preliminarily assembled, so that the composite surface is in a vacuum state and oxidation is prevented; pressure is applied to the preliminarily assembled steel plate and titanium plate, and pulsed current is additionally applied to mechanically engage the steel plate and the titanium plate, so that a group of blanks is formed; the group of blanks is heated, and pulsed current is additionally applied to roll the composite plate; the corrugated steel plate is rolled, and a large pulsed electron beam is used for treatment, so that the corrugated steel plate and the titanium plate are mechanically engaged first, and then the composite plate is formed by heating and engaging; no oxide is formed on the interface after rolling, and the interface bonding strength of the composite plate is improved.

Description

Technical Field

[0001] This invention belongs to the field of composite plate rolling technology, and particularly relates to a method for rolling extra-thick titanium-steel double-layer composite plates with pulse current assistance. Background Technology

[0002] Current titanium / steel composite plate rolling methods employ symmetrical billet assembly, resulting in thick billets that place higher demands on rolling mill forces. Furthermore, it is difficult to separate the composite plates for reuse after rolling. Most critically, existing rolling technologies are largely suitable for thinner metal sheets, lacking effective rolling methods for extra-thick composite plates. In addition, titanium / steel composite plates face other challenges, including low post-rolling bonding strength, excessive interfacial compound formation severely limiting improved bonding strength, and insufficient diffusion of interfacial elements at low temperatures, hindering effective interfacial bonding.

[0003] Therefore, there is an urgent need to design a new process for rolling extra-thick titanium-steel double-layer composite plates using pulsed current assistance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for rolling extra-thick titanium-steel double-layer composite plates with pulsed current assistance, so as to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A method for pulsed current-assisted rolling of extra-thick titanium-steel double-layer composite plates, used for composite forming of steel plates and titanium plates, includes the following steps:

[0007] Corrugated roll rolling, which uses an additional pulsed current to assist in rolling the steel plate, forms a corrugated morphology on the surface of the steel plate so that a local strong force can be formed on the corrugated surface in the subsequent process;

[0008] The composite surface of the steel plate and titanium plate was treated with a large pulse electron beam.

[0009] The steel plate and titanium plate are initially assembled to place the composite surface in a vacuum state to prevent oxidation.

[0010] Pressure is applied to the pre-assembled steel plate and titanium plate, and a pulsed current is applied to make the steel plate and titanium plate mechanically engage to form a preform.

[0011] The billet is heated and a pulsed current is applied to roll the composite plate into shape.

[0012] The heating method used in the heating process of the billet assembly is electromagnetic induction heating.

[0013] The large pulse electron beam processing specifically includes:

[0014] The steel plate and the titanium plate are placed in a pulse electron beam emitting device, and the surface layer of the composite surface is ensured to be in the electron beam irradiation spot range.

[0015] The pulse electron beam emitting device uses a pulse electron beam with an acceleration voltage of 12-16 kV and a pulse current of 50-300 A to irradiate and bombard the surface layer of the composite surface, with a pulse duration of 1-10 μs, a pulse frequency of 0.1-15 Hz, and a pulse number of 1-80.

[0016] The pressure is applied to the preliminarily assembled and formed steel plate and titanium plate, and the pulse current is additionally applied to mechanically engage the steel plate and the titanium plate, specifically including: adjusting the pressure and the current to control the corrugated gap of the composite surface, so that the corrugated surface forms a local strong force to form a strong connection at the interface.

[0017] The pressure is 15-20 MPa, the pulse current is 100-650 A, the pulse frequency is 100-3000 Hz, the duty cycle is 10-60%, and the pressure is maintained for 1-60 min.

[0018] During the heating process of the assembled blank, the heating temperature of the steel plate is 68-950℃, and the heating temperature of the titanium plate is 380-600℃.

[0019] During the rolling process of the composite plate, the pulse current is a square wave pulse current with a pulse current of 200-550 A, a pulse frequency of 0-1500 Hz, and a duty cycle of 10-50%.

[0020] Compared with the prior art, the present application has the following advantages and technical effects: the present application uses large pulse electron beam treatment to make the corrugated steel plate and the titanium plate mechanically engaged first and then heated and engaged to form a composite plate, which ensures that there is no oxide at the interface after rolling and improves the interfacial bonding strength of the composite plate. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor:

[0022] Figure 1 It is a schematic diagram of the pulse current assisted rolling of the steel plate of the present application;

[0023] Figure 2 It is a schematic diagram of the large pulse electron beam treatment of the present application;

[0024] Figure 3 It is a schematic diagram of the preliminary assembly of the present application;

[0025] Figure 4 A schematic diagram of the assembly blank forming of the present application;

[0026] Figure 5 A schematic diagram of the arrangement after the assembly blank forming of the present application;

[0027] Figure 6 A schematic diagram of the heating assembly blank of the present application;

[0028] Figure 7 A schematic diagram of the composite plate rolling of the present application;

[0029] Figure 8 A schematic diagram of the force at different positions of the corrugated interface of the present application;

[0030] Wherein, 1-pulse power supply; 2-corrugated roller; 3-positive electrode brush; 4-flat roller; 5-negative electrode brush; 6-titanium plate; 7-steel plate; 8-vacuum extraction pipe; 9-first guide plate; 10-second guide plate; 11-first electromagnetic induction coil; 12-second electromagnetic induction coil. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0033] A method for pulse current assisted rolling of double-layer composite plate of extra-thick titanium steel, used for the composite forming of steel plate and titanium plate, comprising the following steps:

[0034] The corrugated roller is rolled by additional pulse current assisted rolling of the steel plate, and the surface of the steel plate forms a corrugated appearance, so as to form a local strong force on the corrugated surface subsequently;

[0035] A large pulse electron beam is used for processing the composite surface of the steel plate and the titanium plate;

[0036] The steel plate and the titanium plate are preliminarily assembled, and the composite surface is in a vacuum state to prevent oxidation;

[0037] Pressure is applied to the preliminarily assembled and formed steel plate and titanium plate, and additional pulse current is applied to mechanically engage the steel plate and the titanium plate to form an assembly blank;

[0038] The assembly blank is heated, and the composite plate is rolled and formed by additional pulse current.

[0039] The heating method used in the heating process of the billet assembly is electromagnetic induction heating.

[0040] The large pulse electron beam processing specifically includes:

[0041] The steel plate and titanium plate are placed in a pulsed electron beam emitting device, ensuring that the surface of the composite surface is within the range of the electron beam irradiation spot.

[0042] The pulsed electron beam emitting device uses a pulsed electron beam with an accelerating voltage of 12-16kV and a pulse current of 50-300A to irradiate and bombard the surface of the composite surface. The pulse duration is 1-10μs, the pulse frequency is 0.1-15Hz, and the number of pulses is 1-80.

[0043] Applying pressure to the pre-assembled steel plate and titanium plate, while simultaneously applying a pulsed current to mechanically engage the steel plate and titanium plate, specifically includes: controlling the corrugated gap of the composite surface by adjusting the pressure and current, so that the corrugated surface forms a strong local force to form a strong connection at the interface.

[0044] The pressure is 15-20 MPa, the pulse current is 100-650 A, 100-3000 Hz, and 10-60% duty cycle, and is maintained at the pressure for 1-60 minutes.

[0045] During the heating process of the billet, the heating temperature of the steel plate is 680-950℃; the heating temperature of the titanium plate is 380-600℃.

[0046] The additional pulse current is a square wave pulse current with a frequency of 200-550A, 0-1500Hz, and 10-50% duty cycle during the rolling process of the composite plate.

[0047] Example 1: As Figures 1-8 As shown, the specific steps of the rolling process are as follows: First, a corrugated morphology is prepared on the steel plate by means of pulse current assisted rolling + corrugated roll rolling.

[0048] In one embodiment of the present invention, such as Figure 1 As shown, a positive brush 3 and a negative brush 5 are respectively installed at both ends of the steel plate 7; the positive brush 3 and the negative brush 5 are respectively connected to the positive and negative terminals of the pulse power supply 1; a corrugated roll 2 and a flat roll 4 are respectively set on the top and bottom surfaces of the steel plate 7; a corrugated morphology is formed on the steel plate 1; the function of the pulse current is to enable the corrugated surface to form fine grains on one side, which is beneficial to the diffusion of elements in the subsequent rolling composite process; the function of the corrugated morphology is to form a strong local force at the interface in the subsequent rolling process, promote the extrusion friction of dissimilar metal interfaces, and form a strong connection at the interface.

[0049] Further, local strong force is formed at the position where the steel plate 7 and the titanium plate 6 first contact, and the local strong force is first generated at the wave crest at the initial stage of rolling.

[0050] Secondly, the prepared corrugated surface of the steel plate 7 and the surface to be compounded of the titanium plate 6 are treated by using a high-current pulsed electron beam (HCPEB).

[0051] In an embodiment of the present application, as shown in Figure 2 The HCPEB treatment can obtain a purified surface layer with nanocrystals, dislocations, stacking faults and vacancies, and the high-density grain boundaries, rich crystal defects and deformation structure with low diffusion activation energy can greatly accelerate the diffusion of atoms in the crystal lattice.

[0052] Thirdly, the prepared plate blanks are assembled, and the surrounding is welded and vacuumized, so that the contact interface is in a vacuum state and the interface oxidation is prevented.

[0053] In an embodiment of the present application, as shown in Figure 3 The corrugated surface of the steel plate 7 is buckled on the titanium plate 6, and a vacuum pipe 8 is connected at the compounded contact surface.

[0054] Further, the titanium is easily oxidized at high temperature, and the purpose of vacuumization is to make the interface in an oxygen-free state, so as to ensure that there is no oxide at the interface after rolling, and the poor interface bonding strength caused thereby is avoided.

[0055] Fourthly, different amplitude gaps are formed at the interface to be compounded by the method of pulse current assistance + pressure application, the gap size is adjusted by adjusting the pressure size, so that continuous local strong stress and continuous current tip effect are formed in the subsequent rolling, and the interface is rapidly combined. The pulse current acts to accelerate element diffusion and promote local contact preliminary connection in the pressure application process.

[0056] In an embodiment of the present application, as shown in Figure 4 After vacuumization, pressure F is applied to the steel plate with a preliminarily prepared corrugation and the flat titanium plate, and high-energy pulse current is applied to the blank at the same time. The size of the interface corrugation gap is controlled by controlling the size of the pressure and the current (the effect of applying the pulse current is to reduce the current resistance, promote metal fluidity, accelerate element diffusion in the contact area, and promote preliminary combination of the bimetal), so that local strong stress is formed in the subsequent rolling, and preliminary mechanical engagement is realized; the gap size will affect the current aggregation and tip effect in the subsequent rolling process.

[0057] Fifthly, the completed assembly is heated by electromagnetic induction, and the two materials will be raised to different temperatures in a short time due to the different magnetic conductivity of the two materials, forming a different temperature state; and the rolling is performed under the assistance of the pulse current, so that the composite plate is combined.

[0058] In one embodiment of the present application, as shown in Figures 5-7 The first and second leading plates 9 and 10 are respectively connected to the two ends of the steel plate, and the first and second electromagnetic induction coils 11 and 12 are respectively arranged on the side of the steel plate 7 and the titanium plate 8 away from each other. After heating, the first and second leading plates 9 and 10 are respectively connected to the positive and negative brush electrodes 3 and 5, and the positive and negative brush electrodes 3 and 5 are respectively electrically connected to the pulse power supply. One flat rolling mill 4 is arranged on each side of the blank.

[0059] In one embodiment of the present application, the composite effect of pulse current assisted rolling is that, in the rolling process, the effect of pulse current in the contact tip is used to soften the effect of changing the stress state and grain deformation state of the rolling interface, so as to promote the high-strength combination of the interface and break through the limitations of the traditional method.

[0060] Further, as shown in Figure 8 Due to the different stresses of the corrugated interface, the grains at each position of the interface will have different grain deformation states due to the stress difference.

[0061] In one embodiment of the present application, after the square wave pulse current is loaded, the directional moving electrons pass through the defective lattice point array, the vibration frequency and energy of the atoms increase, the temperature of the lattice point array at the defect is higher, a large number of "hot nuclei" with small size are formed in the material, which promotes the movement of dislocations and other defects, reduces stress concentration, and improves the diffusion ability of atoms after temperature rise. The "hot nuclei" apply compressive stress to the micro-holes and micro-cracks due to thermal expansion, so as to close and fill the micro-holes and micro-cracks, achieve the healing effect, and reduce the micro-defects in the titanium-steel composite plate.

[0062] In this embodiment, 304 stainless steel plate is selected as the substrate, and the size is 110*60*10mm; TC4 titanium plate is selected as the substrate, and the size is 100*55*4mm; a corrugated surface is prepared on the surface of the stainless steel plate by rolling, and a groove is milled in the TC4 to prepare for the subsequent process.

[0063] The prepared titanium plate and stainless steel plate are polished on the contact surface using a steel wire brush to remove the surface oxide layer and cleaned with alcohol or acetone. The cleaned plate is placed in the pulse electron beam emitting device, and the surface to be compounded is ensured to be within the electron beam irradiation spot. Then, the surface layer of the composite surface is irradiated and bombarded by a pulse electron beam with an acceleration voltage of 15kV and a pulse current of 130A, a pulse duration of 5μs, a pulse frequency of 5Hz, and a pulse number of 30 times; and then the plate is taken out.

[0064] The blank is sealed around the four sides and the connection between the welded pipe and the blank using argon protection to prevent the workpiece from being oxidized, and then the welded pipe is welded and sealed after the blank is vacuumed.

[0065] The pressure is 20 MPa, the pulse current is 200 A, the frequency is 1000 Hz, the duty cycle is 20%, and the interface is formed under the pressure for 1 min Figure 4 The interface morphology is shown, and the amplitude gap maximum value reaches 0.5 mm. (The amplitude of the interface formed under different pressure or pulse current parameters is different)

[0066] The prepared plate blank is placed in the electromagnetic induction heating coil, and the heating temperature of the stainless steel is set to 900 DEG C, and the temperature of the titanium plate is 500 DEG C. At this time, compared with the same temperature rolling, the deformation resistance of the two plates is closer, the rolling process is more easily deformed, and it is helpful to the rolling process of high strength combination.

[0067] The above heated composite plate is placed in the rolling mill, and the rolling experiment is carried out by pulse current auxiliary rolling. The rolling process is carried out by square wave pulse current with 350 A, 500 Hz, 50% duty cycle, 35% reduction and 50 r / min rolling speed.

[0068] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation to the present application.

[0069] The above-described embodiments are only preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for pulsed current-assisted rolling of extra-thick titanium-steel double-layer composite plates, used for composite forming of steel plates and titanium plates, characterized in that, Includes the following steps: Corrugated roll rolling involves rolling a steel plate with the assistance of an additional pulsed current, which creates a corrugated morphology on the surface of the steel plate, and subsequently generates a localized strong force on the corrugated surface. The composite surface of the steel plate and titanium plate was treated with a large pulse electron beam. The steel plate and titanium plate are initially assembled to place the composite surface in a vacuum state to prevent oxidation. Pressure is applied to the pre-assembled steel plate and titanium plate, and a pulsed current is applied to make the steel plate and titanium plate mechanically engage to form a preform. The billet is heated and a pulsed current is applied to roll the composite plate into shape; The large pulse electron beam processing specifically includes: The steel plate and titanium plate are placed in a pulsed electron beam emitting device, ensuring that the surface of the composite surface is within the range of the electron beam irradiation spot; The pulsed electron beam emitting device uses a pulsed electron beam with an accelerating voltage of 12-16kV and a pulse current of 50-300A to irradiate and bombard the surface of the composite surface. The pulse duration is 1-10μs, the pulse frequency is 0.1-15Hz, and the number of pulses is 1-80.

2. The method for pulse current-assisted rolling of extra-thick titanium-steel double-layer composite plates according to claim 1, characterized in that: The heating method used in the heating process of the billet assembly is electromagnetic induction heating.

3. The method for pulsed current assisted rolling of extra-thick titanium-steel double-layer composite plates according to claim 1, characterized in that: Applying pressure to the pre-assembled steel plate and titanium plate, while simultaneously applying a pulsed current to mechanically engage the steel plate and titanium plate, specifically includes: controlling the corrugated gap of the composite surface by adjusting the pressure and current, so that the corrugated surface forms a strong local force to form a strong connection at the interface.

4. The method for pulse current-assisted rolling of extra-thick titanium-steel double-layer composite plates according to claim 3, characterized in that: The pressure is 15-20 MPa, the pulse current is 100-650 A, 100-3000 Hz, and 10-60% duty cycle, and is maintained at the pressure for 1-60 minutes.

5. The method for pulse current-assisted rolling of extra-thick titanium-steel double-layer composite plates according to claim 1, characterized in that: During the heating process of the billet, the heating temperature of the steel plate is 680-950℃; the heating temperature of the titanium plate is 380-600℃.

6. The method for pulsed current assisted rolling of extra-thick titanium-steel double-layer composite plates according to claim 1, characterized in that: The additional pulse current is a square wave pulse current with a frequency of 200-550A, 0-1500Hz, and 10-50% duty cycle during the rolling process of the composite plate.

Images