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CN-122013189-A - Online reworking process applied to unqualified six-system aluminum alloy extruded profile

CN122013189ACN 122013189 ACN122013189 ACN 122013189ACN-122013189-A

Abstract

The invention belongs to the technical field of aluminum alloy, and particularly relates to an online reworking process applied to unqualified six-system aluminum alloy extruded profiles. The invention realizes the efficient repair of complex surface defects of unqualified six-system aluminum alloy extruded profiles, wherein an etching solution adopts a compound acid system with accurate proportion, the surface defect area can be selectively dissolved without damaging a matrix, the corrosion inhibitor is compounded by urotropine, benzotriazole and sodium dodecyl sulfate according to an optimized proportion, excessive corrosion is effectively inhibited, and the complexing agent is formed by the synergism of hydroxyethylidene diphosphonic acid, hydrogen peroxide, sulfamic acid and ammonium bifluoride, and can efficiently chelate aluminum ions released in the dissolution process and prevent secondary deposition. The subsequent ash removal step adopts a mixed solution of low-concentration sulfuric acid and hydrogen peroxide, and thoroughly removes etching residues under mild conditions, so that the ash film is prevented from interfering with the subsequent passivation effect.

Inventors

  • WEN JIE
  • TANG HUAN
  • LIU SHAOPENG
  • WANG CHAO

Assignees

  • 江苏和兴汽车科技有限公司

Dates

Publication Date
20260512
Application Date
20260127

Claims (10)

  1. 1. An online reworking process applied to a disqualified six-system aluminum alloy extruded profile is characterized by comprising the following steps of: S1, placing an aluminum alloy profile in an etching solution for etching treatment, and then placing the aluminum alloy profile in an ash removal solution for ash removal treatment; s2, placing the substrate in passivation solution for passivation treatment, and finally drying.
  2. 2. The online reworking process for the disqualified six-system aluminum alloy extruded profile as claimed in claim 1 is characterized in that the etching solvent comprises, by mass, 5-15% sulfuric acid, 1-5% nitric acid, 0.3-0.8% corrosion inhibitor, 0.3-0.8% complexing agent, and the balance water.
  3. 3. The online reworking process for the disqualified hexa-series aluminum alloy extruded profile according to claim 2, wherein the corrosion inhibitor is urotropine, benzotriazole and sodium dodecyl sulfate in a mass ratio of 100 (10-20) to 1-5.
  4. 4. The online reworking process for the disqualified hexa-series aluminum alloy extruded profile according to claim 2, wherein the complexing agent is (15-25): 3-8): 5-15): 1-5, and is composed of hydroxyethylidene diphosphonic acid, hydrogen peroxide, sulfamic acid and ammonium bifluoride.
  5. 5. The online reworking process for a defective six-system aluminum alloy extruded profile according to claim 2, wherein the etching treatment temperature is 20-25 ℃ and the etching treatment time is 150-200s.
  6. 6. The online reworking process for the disqualified six-system aluminum alloy extruded profile according to claim 1, wherein the ash removal solution is a mixed solution of sulfuric acid solution and hydrogen peroxide solution with a mass ratio of 1 (3-5), wherein the concentration of the sulfuric acid solution is 6-10g/L, and the concentration of the hydrogen peroxide solution is 20-40g/L.
  7. 7. The online reworking process for a defective six-system aluminum alloy extruded profile according to claim 1, wherein the ash removal treatment temperature is 22-26 ℃ and the time is 100-150s.
  8. 8. The online reworking process for the disqualified six-system aluminum alloy extruded profile according to claim 1 is characterized in that the passivation solution comprises, by mass, 10-20% of sulfuric acid, 5-15% of hexafluorotitanic acid, 0.05-0.07% of two-dimensional transition metal carbide material, 5-15% of ammonium sulfate, 1-5% of hydrofluoric acid and the balance of water.
  9. 9. The on-line reworking process for a failed six-system aluminum alloy extruded profile as claimed in claim 1, wherein the passivation treatment temperature is 35-45 ℃ and the time is 90-180s.
  10. 10. The online reworking process for a failed six-system aluminum alloy extruded profile according to claim 1, further comprising a hot water washing treatment after the etching treatment, the ash removal treatment and the passivation treatment, wherein the hot water washing treatment is performed at a temperature of 58-62 ℃ for 55-65s.

Description

Online reworking process applied to unqualified six-system aluminum alloy extruded profile Technical Field The invention belongs to the technical field of aluminum alloy, and particularly relates to an online reworking process applied to unqualified six-system aluminum alloy extruded profiles. Background Although the current online reworking process flow of the defective product of the six-system aluminum alloy automobile structural part can deal with common surface defects such as flow marks, watermarks, mottle, oil stains, corrosion, impurities and the like to a certain extent, the defects of various technologies and operation layers are still exposed in actual production and application, and the consistency of reworking efficiency and product quality is severely restricted. Firstly, the existing reworking process generally simply adopts the standard pretreatment process of original normal production, namely 'pre-degreasing-main degreasing-washing-passivation-washing-drying', and the method is not optimized for the special pollution state of returned workpieces. Particularly, for the intractable defects such as deep corrosion or embedded impurities, the repeated use of the strong alkaline cleaning process is difficult to thoroughly remove pollutants, but the corrosion of an aluminum matrix is possibly aggravated by repeated alkaline cleaning, even new microcracks are induced, and the mechanical property and the corrosion resistance of the structural member are further weakened. In the degreasing link, alkaline degreasing agents with the same components and similar concentrations are commonly adopted in the pre-degreasing and main degreasing stages, and reasonable gradient design is lacked. The non-differential treatment mode can not effectively realize gradual stripping of pollutants with different types and different adhesion strengths, and particularly when facing high-adhesion lubricating oil, high-temperature oxidation residues or compound stains, the cleaning efficiency is obviously reduced, so that the problem of partial oil film residue or uneven cleaning still exists after reworking. Moreover, the passivation solution used in the passivation process often contains highly corrosive components such as hydrofluoric acid, hexafluorotitanic acid, etc., and the mechanism of action is extremely sensitive to the process parameters. In the reworking process, if improper control, such as overlong soaking time and large fluctuation of bath solution temperature, or excessive aluminum ion concentration caused by repeated reworking, is easy to cause excessive corrosion of local areas or uneven passivation film thickness, so that new surface defects, such as spots, flow marks and even pitting, are induced. These problems not only affect the quality of the appearance, but may also interfere with the adhesion of the subsequent coating or bonding process, eventually reducing the reliability of the overall vehicle assembly. Disclosure of Invention Aiming at the problems in the prior art, the invention constructs an online reworking process applied to the disqualified six-system aluminum alloy extruded profile. The aim of the invention can be achieved by the following technical scheme: An on-line reworking process applied to a disqualified six-system aluminum alloy extruded profile, which comprises the following steps: S1, placing an aluminum alloy profile in an etching solution for etching treatment, and then placing the aluminum alloy profile in an ash removal solution for ash removal treatment; s2, placing the substrate in passivation solution for passivation treatment, and finally drying. In the online reworking process applied to the unqualified six-system aluminum alloy extruded profile, the etching solvent comprises, by mass, 5-15% sulfuric acid, 1-5% nitric acid, 0.3-0.8% corrosion inhibitor, 0.3-0.8% complexing agent and the balance water. In the online reworking process applied to the unqualified six-system aluminum alloy extruded profile, the corrosion inhibitor is composed of urotropine, benzotriazole and sodium dodecyl sulfate in a mass ratio of 100 (10-20) to 1-5. The corrosion inhibitor is prepared by mixing urotropine, benzotriazole (BTA) and Sodium Dodecyl Sulfate (SDS) according to a specific proportion, can effectively inhibit the cathode and anode processes of a corrosion battery, and forms a layer of composite multidimensional protective film. Then, after the ash removal treatment, the profile is placed in a passivation solution to enhance the corrosion resistance of the profile, and finally the drying treatment is completed. In particular, urotropine and BTA jointly act to work cooperatively in an electrochemical level, so that the urotropine and BTA serve as a cathode corrosion inhibitor to slow down hydrogen evolution reaction on one hand, and a compact chemical adsorption film is formed on the surface of metal to directly prevent the metal from dissolving on the other hand. Meanwhile, SDS is