阅读说明：本技术 一种铝合金焊接件的表面处理方法 (Surface treatment method of aluminum alloy welding piece ) 是由 陈刚 张立君 杨晓禹 王红杰 吴瑜 于 2020-12-16 设计创作，主要内容包括：本发明公开了一种铝合金焊接件的表面处理方法,其特征在于包括以下步骤：1)采用超声冲击设备对铝合金焊接件焊缝两侧的热影响区进行超声冲击,热影响区为四个区域,分别为焊接件A面焊缝两侧的A1区和A2区,焊接件B面焊缝两侧的B1区和B2区,其中A1区与B1区位于焊缝的同一侧,A2区与B2区位于焊缝的同一侧,冲击顺序依次为A1区、B1区、A2区、B2区。本发明通过分区域并按照一定区域顺序进行超声冲击,增加抗应力腐蚀的能力。采用分区域并按照一定区域顺序进行微弧氧化,有效的解决铝合金焊接件在服役过程中海洋环境中应力腐蚀和腐蚀疲劳性能的问题。(The invention discloses a surface treatment method of an aluminum alloy welding piece, which is characterized by comprising the following steps of: 1) the ultrasonic impact equipment is adopted to carry out ultrasonic impact on heat affected zones on two sides of a welding seam of the aluminum alloy welding piece, the heat affected zones are four zones, namely an A1 zone and an A2 zone on two sides of the welding seam of the A surface of the welding piece, and a B1 zone and a B2 zone on two sides of the welding seam of the B surface of the welding piece, wherein the A1 zone and the B1 zone are located on the same side of the welding seam, the A2 zone and the B2 zone are located on the same side of the welding seam, and the impact sequence is an A1 zone, a B1 zone, an A2 zone and. The invention increases the stress corrosion resistance by carrying out ultrasonic impact in regions according to a certain region sequence. By adopting the micro-arc oxidation in regions and according to a certain region sequence, the problems of stress corrosion and corrosion fatigue performance of the aluminum alloy welding part in the marine environment in the service process are effectively solved.)

1. A surface treatment method of an aluminum alloy welded part is characterized by comprising the following steps:

1) ultrasonic impact equipment is adopted to carry out ultrasonic impact on heat affected zones on two sides of a welding seam of an aluminum alloy welding piece, the heat affected zones are four zones, namely an A1 zone and an A2 zone on two sides of the welding seam of the A surface of the welding piece, and a B1 zone and a B2 zone on two sides of the welding seam of the B surface of the welding piece, wherein the A1 zone and the B1 zone are positioned on the same side of the welding seam, the A2 zone and the B2 zone are positioned on the same side of the welding seam, and the impact sequence is an A1 zone, a B1 zone, an A2 zone and a;

2) ultrasonic impact equipment is adopted to carry out ultrasonic impact on the welding seam of the aluminum alloy welding piece, and the welding seam of the surface A of the welding piece is ultrasonically impacted and then the welding seam of the surface B of the welding piece is ultrasonically impacted;

3) cleaning and airing the welding part;

4) the welding piece is processed in different areas by micro-arc oxidation, the welding piece is provided with 5 areas which are an area I positioned at the lower sides of an area A1 and an area B1, an area A1 and an area B1, a welding seam, an area A2 and an area B2 and an area II positioned at the upper sides of an area A2 and an area B2 from bottom to top; the sequence of micro-arc oxidation is as follows: immersing the area I into micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more; then turning over the welding part, and immersing the area II into the micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more; then immersing the micro-arc oxidation substrate in an A2 area and a B2 area until the micro-arc oxidation does not generate electric sparks any more and stops; then turning over the welding part, and immersing the A1 area and the B1 area into the micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more and stops; finally, the welding part is completely immersed into the electrolyte for micro-arc oxidation;

5) and after the micro-arc oxidation treatment is finished, cleaning and drying the welding part.

2. The surface treatment method of an aluminum alloy weld according to claim 1, characterized in that: the areas A1, A2, B1 and B2 in the step 1) are areas which are 30-50 mm away from the welding seam; ultrasonically impacting twice in each area, wherein the first-time ultrasonic impacting current is 1.0-1.8A, the ultrasonic impacting speed is 30-50 mm/min, and the ultrasonic impacting time is (L/30) min- (L/10) min; the secondary ultrasonic impact current is 2.0-2.5A, the ultrasonic impact speed is 30-50 mm/min, and the ultrasonic impact time is (L/30) min- (L/10) min, wherein L is the length of the welding part.

3. The surface treatment method of an aluminum alloy weld according to claim 1, characterized in that: in the step 2), the ultrasonic impact current at the welding seam is 2.0-2.8A, the ultrasonic impact speed is 30-50 mm/min, and the ultrasonic impact time is (L/60) min- (L/30) min, wherein L is the length of the welding part.

4. The surface treatment method of an aluminum alloy weld according to claim 1, characterized in that: in the step 4), the immersion speed of the zone I and the immersion speed of the zone II are 5-10 mm/min, and the immersion speed of the zone A1 and the zone B1, and the immersion speed of the zone A2 and the zone B2 are 2-4.9 mm/min.

5. The surface treatment method of an aluminum alloy weld according to claim 1, characterized in that: the electrolyte for micro-arc oxidation in the step 4) contains 15-40 g/L of sodium silicate, 15-40 g/L of sodium phosphate, 0.5-10 g/L of sodium hydroxide, 0.3-7 g/L of potassium permanganate, 0.5-3 g/L of sodium tungstate and deionized water.

6. The surface treatment method of an aluminum alloy weld according to claim 1, characterized in that: and 4) carrying out micro-arc oxidation treatment on the sample by adopting a double-pulse micro-arc oxidation power supply in the micro-arc oxidation, wherein stainless steel is used as a cathode, a welding piece is used as an anode, and the temperature of the electrolyte is lower than 25 ℃.

7. The surface treatment method of an aluminum alloy weld according to claim 1, characterized in that: micro-arc oxidation process parameters of the area I, the area A1 and the area B1, the area A2 and the area B2 and the area II in the step 4): the voltage is 250-350V, the frequency is 450-500 Hz, and the duty ratio is 10-20%; the technological parameters of the welding part which is completely immersed into the electrolyte for micro-arc oxidation are as follows: the voltage is 350-500V, the frequency is 400-500 Hz, and the duty ratio is 10-20%.

Technical Field

The invention belongs to the technical field of surface treatment of welding parts, and particularly relates to a surface treatment method of an aluminum alloy welding part.

Background

In recent years, with the rapid development of socioeconomic performance, the global energy consumption has been increasing. The aluminum alloy has low density and high specific strength, and the structural weight can be greatly reduced by adopting the aluminum alloy structural member in the fields of ships, automobiles, trains and the like, so that the energy consumption is reduced. Welding is an important way for realizing the connection of the aluminum alloy structure, and the welding process is a complex non-equilibrium heating and cooling process, and the weldment is subjected to uneven heating to generate stress and deformation. Particularly, in the process of welding the aluminum alloy of the thick plate, the welding amount is large due to the plate thickness, the residual stress is also relatively large, and due to the high residual stress, the high-strength aluminum alloy is easy to generate stress corrosion and reduce corrosion fatigue under the atmosphere and ocean environment, so that the aluminum alloy welding piece is cracked.

The existing welded structural part improves the risk of cracking of a welded part by reducing stress corrosion and corrosion fatigue, for example, residual stress is reduced by vibration aging and ultrasonic impact, but the stress corrosion of the welded part cannot be effectively controlled due to improper method control, and micro-arc oxidation, PVD technology, anodic oxidation and the like can effectively reduce corrosion fatigue, improve fatigue life and reduce the possibility of cracking of aluminum alloy welding. Therefore, the existing aluminum alloy welding parts cannot meet the technical field with higher application on stress corrosion and corrosion fatigue.

Therefore, further improvements are needed with respect to the stress corrosion and corrosion fatigue properties of existing aluminum alloy weldments.

Disclosure of Invention

The invention aims to provide a surface treatment method of an aluminum alloy welding piece with excellent stress corrosion and corrosion fatigue performance.

The technical scheme adopted by the invention for solving the technical problems is as follows: a surface treatment method of an aluminum alloy welded part is characterized by comprising the following steps:

1) ultrasonic impact equipment is adopted to carry out ultrasonic impact on heat affected zones on two sides of a welding seam of an aluminum alloy welding piece, the heat affected zones are four zones, namely an A1 zone and an A2 zone on two sides of the welding seam of the A surface of the welding piece, and a B1 zone and a B2 zone on two sides of the welding seam of the B surface of the welding piece, wherein the A1 zone and the B1 zone are positioned on the same side of the welding seam, the A2 zone and the B2 zone are positioned on the same side of the welding seam, and the impact sequence is an A1 zone, a B1 zone, an A2 zone and a;

2) ultrasonic impact equipment is adopted to carry out ultrasonic impact on the welding seam of the aluminum alloy welding piece, and the welding seam of the surface A of the welding piece is ultrasonically impacted and then the welding seam of the surface B of the welding piece is ultrasonically impacted;

3) cleaning and airing the welding part;

4) the welding piece is processed in different areas by micro-arc oxidation, the welding piece is provided with 5 areas which are an area I positioned at the lower sides of an area A1 and an area B1, an area A1 and an area B1, a welding seam, an area A2 and an area B2 and an area II positioned at the upper sides of an area A2 and an area B2 from bottom to top; the sequence of micro-arc oxidation is as follows: immersing the area I into micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more; then turning over the welding part, and immersing the area II into the micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more; then immersing the micro-arc oxidation substrate in an A2 area and a B2 area until the micro-arc oxidation does not generate electric sparks any more and stops; then turning over the welding part, and immersing the A1 area and the B1 area into the micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more and stops; finally, the welding part is completely immersed into the electrolyte for micro-arc oxidation;

5) and after the micro-arc oxidation treatment is finished, cleaning and drying the welding part.

Preferably, the A1, A2, B1 and B2 areas in the step 1) are areas which are 30-50 mm away from the welding seam; ultrasonically impacting twice in each area, wherein the first-time ultrasonic impacting current is 1.0-1.8A, the ultrasonic impacting speed is 30-50 mm/min, and the ultrasonic impacting time is (L/30) min- (L/10) min; the secondary ultrasonic impact current is 2.0-2.5A, the ultrasonic impact speed is 30-50 mm/min, and the ultrasonic impact time is (L/30) min- (L/10) min, wherein L is the length of the welding part. L has the unit of mm. The ultrasonic impact is carried out on the heat affected zone, the heat affected zone is impacted by adopting small current, and then the heat affected zone is further ultrasonically impacted by adopting large current to obtain more uniform surface quality and gradually release residual stress.

Preferably, in the step 2), the ultrasonic impact current at the welding seam is 2.0-2.8A, the ultrasonic impact speed is 30-50 mm/min, and the ultrasonic impact time is (L/60) min- (L/30) min, wherein L is the length of the welding piece. L has the unit of mm. Ultrasonic impact with greater energy is required due to the greater residual stress at the weld and the tendency to higher hardness at the weld.

Preferably, the immersion speed of the zone I and the zone II in the step 4) is 5-10 mm/min, and the immersion speed of the zones A1 and B1, A2 and B2 is 2-4.9 mm/min. Since the first zone and the second zone are the base material positions, ultrasonic treatment is not carried out, and the first zone is a treatment zone, the immersion speed is higher; and the areas A1 and B1, A2 and B2 are subjected to ultrasonic impact, the micro-arc oxidation forming is relatively slow, and the micro-arc oxidation forming is a post-treatment area, so the immersion speed is relatively slow.

Preferably, the electrolyte for micro-arc oxidation in the step 4) contains 15-40 g/L of sodium silicate, 15-40 g/L of sodium phosphate, 0.5-10 g/L of sodium hydroxide, 0.3-7 g/L of potassium permanganate, 0.5-3 g/L of sodium tungstate and deionized water.

Preferably, in the step 4), the sample is subjected to micro-arc oxidation treatment by using a double-pulse micro-arc oxidation power supply, stainless steel is used as a cathode, a welding piece is used as an anode, and the temperature of the electrolyte is lower than 25 ℃.

Preferably, the micro-arc oxidation process parameters of the region I, the region A1 and the region B1, the region A2 and the region B2 and the region II in the step 4) are as follows: the voltage is 250-350V, the frequency is 450-500 Hz, and the duty ratio is 10-20%; the technological parameters of the welding part which is completely immersed into the electrolyte for micro-arc oxidation are as follows: the voltage is 350-500V, the frequency is 400-500 Hz, and the duty ratio is 10-20%. The film is firstly formed in other areas except the welding seam through low voltage, and then the whole is subjected to micro-arc oxidation by adopting large voltage, so that the obtained film layer is more uniform.

The aluminum alloy welding piece after surface treatment by the method has the stress corrosion time of more than 650h under the conditions that the stress level is 180MPa and the stress corrosion solution is 5g/L NaCl solution.

The fatigue life of the aluminum alloy welding piece subjected to surface treatment by adopting the method reaches 1.0 multiplied by 10 under the conditions that the stress level is 100MPa and the stress ratio R is 0.06⁸The above.

Compared with the prior art, the invention has the advantages that: by dividing the regions and carrying out ultrasonic impact according to a certain region sequence, the welding residual stress of different regions can be better released, the residual stress is reduced, and the stress corrosion resistance is improved. The micro-arc oxidation is carried out by regions according to a certain region sequence, and the obtained micro-arc oxidation film layer is more uniform. The ultrasonic impact and micro-arc oxidation composite surface treatment process is adopted, so that the problems of stress corrosion and corrosion fatigue performance in the marine environment of the aluminum alloy welding part in the service process are effectively solved.

Drawings

FIG. 1 is a schematic view of an aluminum alloy weldment according to an embodiment of the present disclosure; wherein T is the thickness.

FIG. 2 is a range of heat affected zones for an aluminum alloy weldment according to an embodiment of the present invention;

FIG. 3 is a schematic view of an ultrasonic impact area and a micro-arc oxidation area of a weld A surface in an embodiment of the invention;

FIG. 4 is a schematic view of the ultrasonic impact area and the micro-arc oxidation area of the B surface of the weldment in the embodiment of the invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The aluminum alloy welded parts of examples 1 to 3 adopt the surface treatment method of the present invention, which comprises the steps of:

1) ultrasonic impact equipment is adopted to carry out ultrasonic impact on heat affected zones on two sides of a welding seam of an aluminum alloy welding piece, the heat affected zones are four zones, namely an A1 zone and an A2 zone on two sides of the welding seam of the A surface of the welding piece, and a B1 zone and a B2 zone on two sides of the welding seam of the B surface of the welding piece, wherein the A1 zone and the B1 zone are positioned on the same side of the welding seam, the A2 zone and the B2 zone are positioned on the same side of the welding seam, and the impact sequence is an A1 zone, a B1 zone, an A2 zone and a; see fig. 2, 3, 4.

2) Ultrasonic impact equipment is adopted to carry out ultrasonic impact on the welding seam of the aluminum alloy welding piece, and the welding seam of the surface A of the welding piece is ultrasonically impacted and then the welding seam of the surface B of the welding piece is ultrasonically impacted;

3) washing the welded part subjected to ultrasonic impact by using acetone or alcohol, then washing by using ultrasonic water, then washing by using alcohol or acetone, washing by using deionized water after washing, and airing after washing;

4) the welding piece is treated in a subarea by micro-arc oxidation, a sample is subjected to micro-arc oxidation by a double-pulse micro-arc oxidation power supply, stainless steel is used as a cathode, the test piece is used as an anode, and the temperature of electrolyte is always kept lower than 25 ℃. The welding part is provided with 5 areas which are an area I positioned on the lower sides of an area A1 and an area B1, an area A1 and an area B1, a welding seam, an area A2 and an area B2 and an area II positioned on the upper sides of an area A2 and an area B2 from bottom to top; the sequence of micro-arc oxidation is as follows: immersing the area I into micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more; then turning over the welding part, and immersing the area II into the micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more; then immersing the micro-arc oxidation substrate in an A2 area and a B2 area until the micro-arc oxidation does not generate electric sparks any more and stops; then turning over the welding part, and immersing the A1 area and the B1 area into the micro-arc oxidation electrolyte until the micro-arc oxidation does not generate electric sparks any more and stops; finally, the welding part is completely immersed into the electrolyte for micro-arc oxidation; see fig. 3, 4.

5) And after the micro-arc oxidation treatment is finished, the welding part is washed by deionized water and then dried.

Comparative example 1 the surface treatment of the aluminum alloy weldment is carried out by using the traditional ultrasonic impact, namely, the surface A (comprising a heat affected zone and a welding seam) of the weldment is impacted firstly, and then the surface B (comprising the heat affected zone and the welding seam) of the weldment is impacted, and the specific parameters of the ultrasonic impact of the example and the comparative example 1 are controlled as shown in table 1.

Comparative example 2 surface treatment was performed on the aluminum alloy welded part by conventional micro-arc oxidation, that is, the aluminum alloy welded part was immersed in the electrolyte at one time, and the specific parameters of the electrolyte and the micro-arc oxidation in examples and comparative example 2 are controlled as shown in tables 2 and 3, respectively.

The samples of examples and comparative examples were subjected to stress corrosion test using an electronic universal tester, and NaCl solution having a stress level of 180MPa and a stress corrosion solution of 5g/L was selected, and the results are shown in Table 4. As can be seen from Table 4, the stress corrosion performance of examples 1 to 3 is greatly improved compared with that of comparative examples 1 to 2, while the stress corrosion performance of example 2 with the best stress corrosion performance is improved by 97.97% compared with that of comparative example 1 and is improved by 55.54% compared with that of comparative example 2.

The fatigue test is completed in a MTS Landmark 370.10 fatigue test system, the stress level is 100MPa, the stress ratio R is 0.06, and when the service life of the sample reaches 1.0 multiplied by 10⁸The test was terminated and the results are shown in table 4. As can be seen from Table 4, no fracture occurred in examples 1 to 3, and fracture occurred in comparative examples 1 to 2, and the fatigue life was less than 1.0X 10⁸。

TABLE 1 weld dimensions and ultrasonic impact processing parameters for examples and comparative example 1

TABLE 2 micro-arc oxidation electrolyte parameters of example and comparative example 2

TABLE 3 micro-arc oxidation Process parameters of example and comparative example 2

TABLE 4 stress corrosion and fatigue Properties of examples and comparative examples

Numbering	Stress corrosion/h	Fatigue life
			Example 1	654.3	1.0×108
Example 2	701	1.0×108
			Example 3	683.8	1.0×108
Comparative example 1	354.6	7.08×107
			Comparative example 2	450.7	8.286×106