Method for eliminating residual stress during explosion of titanium alloy welding part

Abstract

The invention relates to a method for eliminating residual stress during explosion of a titanium alloy welding part. The method comprises the following steps: firstly, fixing a buffer pad along the length direction of a welding seam to cover the welding seam, arranging an explosive strip on the buffer pad, fixedly attaching the explosive strip to the buffer pad through a shaped charge sizing cover, and forming two explosive shock waves at the welding seam to eliminate the residual stress. The welding residual stress can be eliminated without a large heat treatment device, and the stress elimination treatment process of the large titanium alloy welding part is simplified. Meanwhile, the energy-gathered charging shaping cover is utilized to generate an energy-gathered effect on explosives, two shock waves can be generated through one-time explosion, the utilization efficiency of explosive shock wave energy of the explosives is greatly improved, the effective action range of eliminating residual stress is effectively widened, the use amount of the explosives is reduced, and the explosive efficiency is greatly improved under the condition of the same explosive amount. And the elimination effect of the overall residual stress of the material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to a method for explosion eliminating residual stress of titanium alloy welded parts, and more particularly to a method for explosion eliminating residual stress of large-thickness titanium alloy welded parts. BACKGROUND

[0002] In the prior art, annealing and ultrasonic wave are usually used to eliminate residual stress of metal parts after welding.

[0003] The annealing usually needs to place the whole welded part in a heating furnace for heating, holding and cooling. For large parts and welded parts which are not suitable for heat treatment equipment before welding, the annealing process is difficult to implement. In addition, stress relieving annealing can only reduce the residual stress of welding, and usually retains more than 15% of the residual stress. Moreover, the heat treatment of titanium alloy has strict requirements on the process. The ultrasonic wave stress relieving is usually suitable for stress relieving treatment of small and thin parts, and is easy to damage the weld surface.

[0004] There are also methods for eliminating residual stress of welded parts by explosion, but if not properly controlled, it is easy to damage the welded parts and cause safety accidents.

[0005] Therefore, there is an urgent need for an explosion stress relieving device that can be used conveniently and is not limited by the structure size, so as to facilitate the stress relieving treatment of large-thickness titanium alloy large welded parts. SUMMARY

[0006] The purpose of the present application is to provide an improved method for explosion eliminating residual stress of titanium alloy welded parts. Through the improvement of the method, the stress relieving treatment process of large-thickness titanium alloy welded parts is simplified, the residual stress of welding can be effectively eliminated, the weld surface is not easy to be damaged, and the treatment cost is reduced.

[0007] In order to achieve the above purpose, the technical scheme of the present application is as follows: a method for explosion eliminating residual stress of titanium alloy welded parts, characterized in that the method comprises the following steps: a, setting a buffer pad: after welding of a titanium alloy metal part, a buffer pad is fixed along the length direction of the weld joint area of the welded joint of the titanium alloy metal part to cover the weld; b, setting an explosive: an explosive strip is set on the buffer pad, and then the explosive strip is fixed and attached to the buffer pad through an energy-gathering charge shaping cover; c, detonating the explosive, forming two explosion shock waves at the weld to eliminate residual stress.

[0008] Preferably, in step a, the buffer pad has a strip structure, is arranged along the weld direction, has a length equal to the weld, and has a width covering the weld.

[0009] Further, when the welding thickness of the titanium alloy welded part is greater than or equal to 30 mm, buffer pads and explosive strips are arranged on the front and back surfaces of the weld respectively, and residual stress is effectively eliminated by double-side detonation.

[0010] Furthermore, in step b, the explosive strips are laid along the weld direction, with a length flush with the weld. The explosive strips use a flexible, adhesive gel-like explosive with RDX as the main explosive agent. The explosive strips have the following weight percentage composition: 89%–92% RDX, 6%–8% fluororubber, 1%–2% dioctyl sebacate, and 1% liquid paraffin.

[0011] Further, in step b, the relationship between the unit charge V of the explosive strip, the weld width W, and the yield strength σY of the metal component is: V = (0.002 - 0.005)·W·σY, where the unit charge V is measured in g / m, the weld width W in mm, and the yield strength σY of the metal component in MPa. The shaped charge shroud is a PVC semi-circular shroud, and the explosive strip is encapsulated inside the shaped charge shroud. The density of the explosive is 0.9 g / cm³. 3 -1.5g / cm 3 The detonation velocity of the explosive is 4800m / s to 7000m / s.

[0012] Furthermore, in step c, when the explosive bar explodes, it generates impacts in all directions. The shock wave toward the weld is the first shock wave, causing the metal material at the weld to undergo plastic deformation. The impact toward the shaped charge shroud is reflected to form a second shock wave, which penetrates the surface of the metal weld, causing the metal material at the weld to undergo plastic deformation again, thus eliminating residual welding stress.

[0013] Compared with the prior art, the technical solution of the present invention not only improves the overall technical solution, but also includes many improvements in details. Specifically, it has the following beneficial effects: 1. The improved solution of the present invention fixes a buffer pad along the length of the weld in the joint area of ​​the metal part welding, sets an explosive strip on the buffer pad, and then fixes the explosive strip to the buffer pad by a shaped charge shaping cover, detonates the explosive, and forms two explosive shock waves at the weld to eliminate residual stress. It can eliminate welding residual stress without the need for a large heat treatment device, and simplifies the stress relief process of large titanium alloy welded parts, reducing manufacturing process costs. 2. In the method of the present invention, the shaped charge shroud is used to generate a shaped charge effect on the explosive, which can generate two shock waves, greatly improving the utilization efficiency of the explosive shock wave energy, effectively increasing the effective range of residual stress elimination, reducing the amount of explosive used, and improving the overall residual stress elimination effect of the material under the same explosive charge. 3. In the method of the present invention, when the welding thickness of the titanium alloy welded part is ≥30mm, buffer pads and explosive strips are respectively arranged on the front and back sides of the weld, and the residual stress is effectively eliminated by double-sided detonation, which further increases the stress elimination effect and improves efficiency. 4. The method of the present invention is easy to implement and convenient to deploy. It does not require large-scale setup, has wide applicability, and can be applied to various sizes and specifications, making it easy to promote and utilize. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention.

[0015] Figure 2 This is a schematic diagram of the structure of the present invention, which involves laying a buffer pad along the weld seam.

[0016] Figure label: 1. Titanium alloy welded parts, 2. Buffer pad, 3. Shaped charge housing containing explosive strips. Detailed Implementation

[0017] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a method for explosively eliminating residual stress in titanium alloy welded parts, see details below. Figure 1 The difference between this method and existing technologies lies in the following steps: a) Setting a buffer pad: After welding the titanium alloy metal parts, a buffer pad is fixed along the length of the weld in the joint area to cover the weld; b) Setting explosives: Explosive strips are set on the buffer pad, and then the explosive strips are fixed to the buffer pad by a shaped charge shroud; c) Detonating the explosives to form two explosive shock waves at the weld to eliminate residual stress.

[0019] In use, the explosive charge placed on the weld seam is detonated, creating two explosive shock waves at the weld seam to eliminate residual stress. This eliminates welding residual stress without the need for large heat treatment equipment and simplifies the stress relief process for large titanium alloy welded parts. Simultaneously, the shaped charge shroud provides focused energy to the explosive, generating two shock waves in a single detonation. This significantly improves the utilization efficiency of the explosive shock wave energy, effectively increasing the effective range for eliminating residual stress, reducing the amount of explosive used, and improving the overall residual stress elimination effect on the material with the same amount of explosive.

[0020] Example 1 This embodiment describes a method for eliminating residual stress in titanium alloy welded parts by explosion. The method includes the following steps: a) setting a buffer pad: after welding the titanium alloy metal parts, a buffer pad is fixed along the length of the weld in the joint area to cover the weld; b) setting explosives: an explosive strip is set on the buffer pad, and then the explosive strip is fixed to the buffer pad by a shaped charge shroud; c) detonating the explosives to form two explosive shock waves at the weld to eliminate residual stress.

[0021] Specifically, in step a, the thickness of the thick titanium alloy welded part 1 is ≥20mm. The buffer pad 2 has a strip-shaped structure, arranged along the weld direction, with its length flush with the weld and its width covering the weld. The explosive strip is also arranged along the weld direction, with its length flush with the weld. The explosive strip uses a flexible adhesive gel explosive with RDX as the main explosive agent. By setting a shaped charge shaping cover outside the explosive strip, a shaped charge shaping cover 3 containing the explosive strip is formed.

[0022] Furthermore, when the weld thickness of the titanium alloy weldment is ≥30mm, buffer pads and explosive strips are simultaneously placed on both sides of the weld, and residual stress is effectively eliminated by double-sided detonation.

[0023] In step b, the relationship between the unit charge V of the explosive strip, the weld width W, and the yield strength σY of the metal component is: V = (0.002 - 0.005)·W·σY, where the unit charge V is measured in g / m, the weld width W in mm, and the yield strength σY of the metal component in MPa. The shaped charge shroud is a PVC semi-circular shroud, and the explosive strip is encapsulated inside the shaped charge shroud. The density of the explosive is 0.9 g / cm³. 3 -1.5g / cm 3 The detonation velocity of the explosive ranges from 4800 m / s to 7000 m / s. The explosive performance is related to its density and detonation velocity. Increasing the density of the explosive increases the energy density per unit volume and simultaneously increases the detonation velocity. Explosives with different detonation velocities induce different stress wave parameters in metal components. The energy-concentrating effect of the shaped charge can also effectively improve the work efficiency with the same charge weight. Flexible bonded gel explosives use hexylene as the main explosive agent, with added polymers and plasticizers to bind the high-energy explosive components into a plastic explosive with specific mechanical properties. It exhibits stable detonation performance, low density, reliable initiation and propagation, and easy shaping. The hexylene content is 89%–92% by weight, fluororubber 6%–8%, dioctyl sebate 1%–2%, and 1% liquid paraffin as a desensitizer to reduce sensitivity and improve safety.

[0024] Furthermore, in step c, when the explosive detonates, it generates impacts in all directions. The shock wave directed towards the weld is the first shock wave, causing plastic deformation of the metal material at the weld. The impact directed towards the shaped charge shroud, after reflection, forms a second shock wave that penetrates the surface of the metal weld, causing the metal material at the weld to generate reflected waves. The Mach wave synthesized from the incident and reflected waves causes the metal component to undergo further plastic deformation. Both shock waves act on the metal component, improving the utilization rate of the explosive detonation shock wave energy and achieving a stress relief effect.

[0025] Example 2 In this embodiment, titanium alloy welded components are used, and the welding test plate is 500mm long, 400mm wide, and 30mm thick. During welding, matching titanium alloy welding wire is selected, and a double-sided alternating manual TIG welding process is used to form a strip-shaped weld.

[0026] Specifically, the 30mm thick titanium alloy has a yield strength of 795MPa, a weld width of 15mm, and the explosive is a flexible, binder-like explosive primarily composed of RDX, with a density of 1.2g / cm³. 3 Using the formula: V=(0.002-0.005)·W·σY, where the unit of measurement for the explosive charge V is g / m, the unit of measurement for the weld width W is mm, and the unit of measurement for the yield strength σY of the metal part is MPa, the calculation coefficient for the unit charge of the explosive is taken as 0.003, the unit charge of the explosive used is 36g / m, and the charge of each explosive strip is 42g (the change in material yield strength and weld width makes V increase by 2 times). Two 42g portions of explosive are respectively made into semi-circular explosive strips with a width of 20mm, a thickness of 3.5mm, and a length of 500mm.

[0027] Two buffer pads with a thickness of 3mm are fixed with glue on both sides of the weld on the upper surface of the welding test plate, and the two ends of the two buffer pads extend to be flush with the two ends of the weld. Two explosive strips are fixed with glue to the upper surfaces of the two buffer pads, and the two ends of the two explosive strips are flush with the two ends of the weld. The explosives are detonated in the air.

[0028] The residual stress at the center of the weld was measured before and after the explosion treatment, as shown in Table 1 and Table 2.

[0029] Table 1 shows the residual stress at the weld center before the explosive treatment. Table 2 shows the residual stress at the weld center before the explosive treatment. The following conclusions can be drawn from the data in Tables 1 and 2: Before the workpiece was exploded, the average stress value of the maximum principal stress at the four points was 238.82 MPa. After the explosion, the average stress value of the maximum principal stress at the four points was 88.29 MPa, and the residual stress elimination rate was 63.03%. After the workpiece was exploded, the residual stress at the four points was tested using the X-ray method. The test location was the center of the weld, perpendicular to the weld direction; the average stress at the four points was -169.33 MPa.

[0030] In actual production, when eliminating welding stress on small and medium-sized metal parts, buffer strips and explosives can be fixed to the metal parts and then detonated using the enhanced effect of shaped charge blasting. When eliminating welding stress on large components, the amount of explosives can be adjusted according to the thickness and size of the large components to effectively eliminate welding residual stress on water-immersed objects, such as the bottom plate of ships and offshore drilling platforms, thus expanding the scope of application of the explosive method for eliminating welding residual stress.

[0031] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for explosively eliminating residual stress in titanium alloy welded parts, characterized in that: The method includes the following steps: a) Setting a buffer pad: After welding the titanium alloy metal parts, a buffer pad is fixed along the length of the weld in the joint area to cover the weld; b) Setting explosives: Explosive strips are set on the buffer pads, and then the explosive strips are fixed to the buffer pads by a shaped charge shroud; c) Detonating the explosives to form two explosive shock waves at the weld to eliminate residual stress.

2. The method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: In step a, the buffer pad is a strip structure, laid along the weld direction, with its length flush with the weld and its width covering the weld.

3. The method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: When the weld thickness of titanium alloy welded parts is ≥30mm, buffer pads and explosive strips are placed on both sides of the weld, and residual stress is effectively eliminated by double-sided detonation.

4. The method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: In step b, the explosive strips are laid along the direction of the weld, with the length flush with the weld. The explosive strips use a flexible adhesive gel explosive with RDX as the main explosive agent.

5. The method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: In step b, the relationship between the unit charge V of the explosive strip, the weld width W, and the yield strength σY of the metal part is: V = (0.002 - 0.005)·W·σY, where the unit charge V is measured in g / m, the weld width W is measured in mm, and the yield strength σY of the metal part is measured in MPa.

6. The method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: In step b, the shaped charge shroud is a PVC semi-circular shroud, and the explosive strip is sealed inside the shaped charge shroud.

7. The method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: In step c, when the explosive bar detonates, it generates impacts in all directions. The shock wave toward the weld is the first shock wave, which causes plastic deformation of the metal material at the weld. The impact toward the shaped charge shroud is reflected to form the second shock wave, which enters the surface of the metal weld and causes plastic deformation of the metal material at the weld again, eliminating residual welding stress.

8. The method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: In step b, the density of the explosive is 0.9 g / cm³. 3 -1.5g / cm 3 The detonation velocity of the explosive is 4800m / s to 7000m / s.

9. A method for explosively eliminating residual stress in titanium alloy welded parts according to claim 1, characterized in that: In step b, the weight percentage of the explosive strips is as follows: It contains 89%–92% thiocyanate, 6%–8% fluororubber, 1%–2% dioctyl sebacate and 1% liquid paraffin.

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