Welding sealing method for titanium alloy shell and stainless steel igniter

Abstract

A welding and sealing method for a titanium alloy shell and a stainless steel igniter comprises the steps that brazing filler metal containing scaling powder is placed at the position, to be welded, of a titanium alloy ring, a stainless steel ring is assembled through a limiting tool, overflowing objects are cleaned up, and an adapter ring structure is obtained; the adapter ring structure is integrally placed in a vacuum brazing furnace, and the vacuum degree, the temperature, the heat preservation time and the pressure applied to the whole are set; residues at the brazed position of the adapter ring are polished and cleaned; detecting the air tightness of the adapter ring by using an air tightness detection device; sleeving the adapter ring into the igniter, and performing laser welding sealing on the igniter and the stainless steel ring side of the adapter ring; the igniter with the adapter ring is installed in the titanium alloy shell, and laser welding sealing is conducted on the titanium alloy shell and the titanium alloy ring side of the adapter ring; introducing gas with required pressure into the input end of the titanium alloy shell, maintaining the pressure for a certain period of time, and detecting that the laser welding and brazing positions have no gas leakage phenomenon; and cleaning the welding seam, coating a layer of three-proofing protective agent at each welding position, and curing at room temperature.

Description

Technical Field

[0001] The invention relates to a welding sealing method for a titanium alloy shell and a stainless steel igniter, which is suitable for sealing connection between a shell and an igniter of a starter product and belongs to the field of pyrotechnics. Background Art

[0002] After the starter-type pyrotechnics work, the high-temperature and high-pressure gas in the working chamber needs to be sealed for a long time. The shell of the combustion chamber is usually made of high-strength titanium alloy material, and the igniter connected to it is usually made of stainless steel. Metal gaskets are used at the connection between the two, and a large torque is applied for sealing. Under the action of high temperature and high pressure (≥300℃, ≥10MPa) for a long time, it is difficult to maintain a stable and good sealing effect. In addition, the method of sealing by torque loading has the risk of stress relaxation after long-term storage of the product, and a stable sealing effect cannot be achieved during long-term storage.

[0003] Based on this, it is proposed to use welding to achieve a long-term sealed connection between the titanium alloy starter shell and the stainless steel igniter. Since both the titanium alloy shell and the stainless steel igniter contain explosives and other non-metallic devices, they cannot be directly brazed at high temperature (≥150°C), and low thermal effect fusion welding (laser welding, electron beam welding) cannot stably achieve high-strength sealing of the two. Therefore, it is proposed to first braze a dissimilar metal sealing ring, and then laser weld it to the titanium alloy shell and the stainless steel igniter respectively. Finally, a stable sealed connection between the two is achieved.

[0004] Patent CN110421223A discloses a method for high-strength laser welding of titanium alloy and stainless steel using copper-based brazing filler metal. This method places a 0.2 mm thick copper-based brazing filler metal sheet between the stainless steel and titanium alloy joints, and uses a continuous fiber laser to laser weld the dissimilar metal joints. The control method is that the laser deflects (1 to 1.5) mm to the stainless steel side, and the laser melts the stainless steel and copper-based brazing filler metal, so that the copper-based brazing filler metal is wetted on the titanium alloy side to form a brazed connection, eliminating the risk of stainless steel and titanium alloy directly contacting to form brittle and hard intermetallic compounds. The welded structure has no defects such as cracks, and the tensile strength is 210 MPa. Since direct laser welding of stainless steel and titanium alloy requires very precise control, once there is a slight deviation in the laser offset, the titanium alloy is melted, and the stainless steel and titanium alloy are at risk of forming brittle intermetallic compounds, resulting in cracking of the joint. This is unacceptable to the aerospace field, so a more reliable and stable connection method is required to achieve a sealed connection between stainless steel and titanium alloy. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a welding and sealing method for a titanium alloy shell and a stainless steel igniter, and to achieve laser welding and sealing connection between the titanium alloy and the stainless steel.

[0006] The technical solution of the present invention is: a welding and sealing method of a titanium alloy shell and a stainless steel igniter, comprising: the igniter and the titanium alloy shell are respectively welded to an adapter ring to achieve sealing; the adapter ring comprises: a stainless steel ring, a titanium alloy ring, and a brazing material;

[0007] The welding sealing method is:

[0008] The solder containing flux is placed at the position of the titanium alloy ring to be welded, and the stainless steel ring is assembled by using a limiting fixture, and the overflowed flux and pollutants are wiped off to obtain a transfer ring structure;

[0009] Place the adapter ring structure as a whole into a vacuum brazing furnace, and set the vacuum degree, temperature, holding time, and pressure applied to the whole;

[0010] Grind away the residue at the brazing part of the adapter ring; use the airtightness detection device to detect the airtightness of the adapter ring;

[0011] Insert the adapter ring into the igniter, and seal the igniter and the stainless steel ring side of the adapter ring by laser welding;

[0012] The igniter with the adapter ring is installed in the titanium alloy housing, and the titanium alloy housing and the titanium alloy ring side of the adapter ring are sealed by laser welding;

[0013] Introduce gas of required pressure into the input end of the titanium alloy shell and maintain the pressure for a certain period of time. Check that there is no leakage at the laser welding and brazing locations.

[0014] Clean the welds, apply a layer of three-proof protective agent on each welding position and cure it at room temperature.

[0015] Preferably, the stainless steel ring is made of 1Cr18Ni9Ti, the titanium alloy ring is made of TC4, and the solder is made of silver-based solder Ag72Cu28.

[0016] Preferably, when the adapter ring structure is placed in a vacuum brazing furnace, the vacuum degree is set to: 3×(10 -2 ~10 -3 )Pa, set the temperature to 850℃±10℃, set the insulation time to 8min~15min, and apply a pressure of 0.05MPa~0.3MPa to the entire adapter ring structure.

[0017] Preferably, when the air tightness of the adapter ring is tested using an air tightness testing device, the air tightness should meet the sealing requirement of 12 MPa / 10 min without air leakage.

[0018] Preferably, when the igniter and the stainless steel ring side of the adapter ring are laser welded and sealed, the laser welding parameters are:

[0019] Spot diameter 100um, laser power 500W±50W, welding time 1.5s~2s, defocus 0mm~-0.5mm, argon flow rate 10L / min~15L / min.

[0020] Preferably, when the titanium alloy housing and the titanium alloy ring side of the adapter ring are laser welded and sealed, the laser welding parameters are:

[0021] Spot diameter 100um, laser power 600W±50W, welding time 1.5s~2s, defocus 0mm~-0.5mm, argon flow rate 10L / min~15L / min.

[0022] Preferably, when gas of required pressure is introduced into the input end of the titanium alloy shell and the pressure is maintained for a certain period of time, the parameter is set to 12 MPa / 10 min.

[0023] Preferably, the triple-proof protective agent is DBSF-6102;

[0024] Curing at room temperature for 2h to 3h.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The present invention adopts the method of laser welding and sealing of the adapter ring, which can achieve a high-strength sealed connection between the stainless steel igniter and the titanium alloy shell. The adapter ring can be adjusted according to different product structures, and has the advantages of good design and good appearance of the product after welding;

[0027] (2) The present invention adopts brazed dissimilar metal adapter ring laser welding to seal titanium alloy and stainless steel, which has low heat input of the weld, small overall temperature rise of the product, no effect on non-metallic components and explosives in the product, and good safety;

[0028] (3) The present invention uses an adapter ring to laser weld and seal stainless steel and titanium alloy, which can withstand harsh mechanical and environmental conditions, has good long-term storage performance, and has stable product sealing performance in high temperature and high pressure environments (≤500°C, ≤12MPa). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a cross-sectional view of the brazing structure of the adapter ring of the present invention;

[0030] Figure 2 This is a cross-sectional view of the laser welding sealing structure of the titanium alloy shell and the stainless steel igniter of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is: comprising an adapter ring (composed of a stainless steel ring (1Cr18Ni9Ti), a titanium alloy ring (TC4), a brazing material (silver-based brazing material Ag72Cu28)), a stainless steel igniter, and a TC4 titanium alloy shell. The adapter ring is prepared by brazing the stainless steel ring and the titanium alloy ring in a vacuum environment using a silver-based brazing material, and then the adapter ring is laser welded to the stainless steel igniter and the titanium alloy shell to achieve sealing.

[0032] The welding sealing method mainly includes the following steps:

[0033] 1) In 3×(10 -2 ~10 -3 )Pa vacuum environment, using Ag72Cu28 brazing material to braze and seal the stainless steel / titanium alloy adapter ring, the brazing holding temperature is (850±10)℃, the holding time is (8~15)min, and the pressurization pressure is (0.05~0.3)MPa;

[0034] 2) Use sandpaper to polish the brazing area to remove the overflowed brazing material and brazing flux residue;

[0035] 3) Use an airtightness detection device to test the airtightness of the brazing part of the stainless steel / titanium alloy adapter ring, and the airtightness should meet the sealing requirement of 12MPa / 10min without air leakage;

[0036] 4) Insert the adapter ring into the stainless steel igniter, and seal the stainless steel side of the igniter and the stainless steel side of the adapter ring by laser welding (laser welding parameters: spot diameter 100um, laser power (500±50)W, welding time (1.5~2)s, defocus (0~-0.5)mm, argon flow rate (10~15)L / min);

[0037] 5) Install the igniter with the adapter ring into the titanium alloy housing, and seal the titanium alloy side of the housing and the titanium alloy side of the adapter ring by laser welding (laser welding parameters: spot diameter 100um, laser power (600±50)W, welding time (1.5-2)s, defocus (0--0.5)mm, argon gas flow rate (10-15)L / min);

[0038] 6) Introduce gas of required pressure into the input end of the titanium alloy shell and maintain the pressure for a certain period of time (such as 12MPa / 10min). Check that there should be no leakage at the laser welding and brazing points.

[0039] Example:

[0040] like Figure 1As shown, a welding sealing method of titanium alloy and stainless steel of the present invention comprises a 1Cr18Ni9Ti stainless steel ring 1, an Ag72Cu28 solder 2, a TC4 titanium alloy ring 3, a 1Cr18Ni9Ti igniter 4, and a TC4 titanium alloy shell 5. The adapter ring comprises: a stainless steel ring 1 (1Cr18Ni9Ti), a titanium alloy ring 3 (TC4), and a solder 2 (silver-based solder Ag72Cu28).

[0041] The present invention implements the steps as follows:

[0042] 1. Place the Ag72Cu28 solder 2 containing flux on the titanium alloy ring 3 to be welded, and use the limit fixture to assemble the 1Cr18Ni9Ti stainless steel ring 1, and clean the overflowed flux and pollutants;

[0043] 2. Place the whole into a vacuum brazing furnace and set the vacuum degree to 3×(10 -2 ~10 -3 )Pa, (850±10)℃, holding time is (8~15)min, and the pressure applied to the whole is about (0.05~0.3)MPa;

[0044] 3. Use sandpaper to clean the flux, brazing material and other residues overflowing from the brazing area of ​​the adapter ring. Use the airtightness detection device to detect that the adapter ring meets the airtightness requirements (12MPa / 10min) and there is no air leakage;

[0045] 4. Put the adapter ring into the stainless steel igniter, and laser weld and seal the stainless steel side of the igniter and the stainless steel side of the adapter ring (laser welding parameters: spot diameter 100um, laser power (500±50)W, welding time (1.5~2)s, defocus (0~-0.5)mm, argon flow rate (10~15)L / min);

[0046] 5. Install the igniter with the adapter ring into the titanium alloy housing 5, and seal the titanium alloy side of the housing and the titanium alloy side of the adapter ring by laser welding (laser welding parameters: spot diameter 100um, laser power (600±50)W, welding time (1.5-2)s, defocus (0--0.5)mm, argon gas flow rate (10-15)L / min);

[0047] 6. Introduce the required pressure of gas into the input end of the titanium alloy shell and maintain the pressure for a certain period of time (such as 12MPa / 10min). Check that there is no leakage at the laser welding and brazing points;

[0048] 7. Clean the weld, apply a thin layer of triple-proof protective agent (DBSF-6102) on each welding position and cure it at room temperature for (2-3) hours.

[0049] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

Claims

1. A welding and sealing method for a titanium alloy shell and a stainless steel igniter, characterized in that include: The igniter (4) and the titanium alloy housing (5) are respectively welded to the adapter ring to achieve sealing; the adapter ring comprises: a stainless steel ring (1), a titanium alloy ring (3), and a brazing material (2); The welding sealing method is: The solder (2) containing flux is placed at the position to be welded of the titanium alloy ring (3), and is assembled into the stainless steel ring (1) by using a limiting fixture, and the overflowed flux and contaminants are wiped off to obtain a transfer ring structure; Place the adapter ring structure as a whole into a vacuum brazing furnace, and set the vacuum degree, temperature, holding time, and pressure applied to the whole; Grind away the residue at the brazing part of the adapter ring; use the airtightness detection device to detect the airtightness of the adapter ring; Insert the adapter ring into the igniter, and laser weld the igniter (4) and the stainless steel ring (1) side of the adapter ring to seal; The igniter with the adapter ring is installed in the titanium alloy housing (5), and the titanium alloy housing (5) and the titanium alloy ring (3) side of the adapter ring are sealed by laser welding; A gas of required pressure is introduced into the input end of the titanium alloy shell (5) and the pressure is maintained for a certain period of time, and it is detected that there is no gas leakage at the laser welding and brazing locations; Clean the welds, apply a layer of three-proof protective agent on each welding position and cure it at room temperature.

2. The welding and sealing method of a titanium alloy shell and a stainless steel igniter according to claim 1, characterized in that: The stainless steel ring (1) is made of 1Cr18Ni9Ti, the titanium alloy ring (3) is made of TC4, and the brazing material (2) is made of silver-based brazing material Ag72Cu28.

3. The welding and sealing method of a titanium alloy housing and a stainless steel igniter according to claim 1, characterized in that: When the adapter ring structure is placed in a vacuum brazing furnace, the vacuum degree is set to: 3×(10 -2 ~10 -3 )Pa, set the temperature to 850℃±10℃, set the insulation time to 8min~15min, and apply a pressure of 0.05MPa~0.3MPa to the entire adapter ring structure.

4. The welding and sealing method of a titanium alloy housing and a stainless steel igniter according to claim 1, characterized in that: When using an airtightness detection device to detect the airtightness of the adapter ring, the airtightness should meet the sealing requirement of 12MPa / 10min without air leakage.

5. The welding and sealing method of a titanium alloy housing and a stainless steel igniter according to claim 1, characterized in that: When the igniter (4) and the stainless steel ring (1) side of the adapter ring are sealed by laser welding, the laser welding parameters are: Spot diameter 100um, laser power 500W±50W, welding time 1.5s~2s, defocus 0mm~-0.5mm, argon flow rate 10L / min~15L / min.

6. The welding and sealing method of a titanium alloy housing and a stainless steel igniter according to claim 1, characterized in that: When the titanium alloy housing (5) and the titanium alloy ring (3) side of the adapter ring are laser welded and sealed, the laser welding parameters are: Spot diameter 100um, laser power 600W±50W, welding time 1.5s~2s, defocus 0mm~-0.5mm, argon flow rate 10L / min~15L / min.

7. The welding and sealing method of a titanium alloy housing and a stainless steel igniter according to claim 1, characterized in that: When gas at a required pressure is introduced into the input end of the titanium alloy housing (5) and the pressure is maintained for a certain period of time, the parameter is set to 12 MPa / 10 min.

8. The welding and sealing method of a titanium alloy housing and a stainless steel igniter according to claim 1, characterized in that: The triple protection agent uses DBSF-6102; Curing at room temperature for 2h to 3h.

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