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CN-122013099-A - Surface composite strengthening method for precipitation hardening stainless steel high-pressure pipe quick connector

CN122013099ACN 122013099 ACN122013099 ACN 122013099ACN-122013099-A

Abstract

The invention discloses a precipitation hardening stainless steel high-pressure pipe quick joint surface composite strengthening method, which relates to the technical field of stainless steel surface strengthening and comprises the following steps of S1, rough machining, S2, complete solution treatment under vacuum or protective atmosphere, oil quenching to room temperature, S3, aging treatment under vacuum or protective atmosphere, air cooling to room temperature, S4, semi-finishing, allowance setting, S5, multistage shot blasting, precise polishing, cleaning and drying, and S6, depositing gradient/multilayer Cr/CrN coating or Cr/CrN/CrCN coating on the surface of a pipe joint by adopting a low-temperature PVD process. The invention realizes the high-quality surface strengthening treatment of the surface material of the precipitation hardening stainless steel high-pressure pipe joint, meets the requirement of reliability performance under extreme compound working conditions (high pressure, high wear resistance and severe corrosion conditions), and effectively solves the problems of short service life, insufficient reliability and the like under high load, high wear and severe corrosion environments.

Inventors

  • ZHAO JUNWEN
  • GUO SHUANGQUAN
  • CHEN BO
  • LIU GANG
  • DONG LIXIN

Assignees

  • 成都浩瑞格科技有限责任公司

Dates

Publication Date
20260512
Application Date
20260126

Claims (10)

  1. 1. The surface composite strengthening method for the quick connector of the precipitation hardening stainless steel high-pressure pipe is characterized by comprising the following steps of: S1, roughly machining a material to the shape of a pipe joint; S2, placing the pipe joint in vacuum or protective atmosphere for complete solution treatment, and quenching oil to room temperature; S3, aging the pipe joint under vacuum or protective atmosphere, and air-cooling to room temperature; S4, semi-finishing the pipe joint, and leaving the residual of shot blasting, polishing and PVD coating; S5, performing multistage shot blasting on the pipe joint, then performing precise polishing, flattening the wave crest on the surface, reserving the wave trough and the compressive stress layer below, reducing the roughness, and then cleaning and drying; S6, depositing a gradient/multi-layer Cr/CrN coating or a Cr/CrN/CrCN coating containing a Cr metal bonding layer on the surface of the pipe joint by adopting a low-temperature PVD process.
  2. 2. The method for surface-composite strengthening of a rapid joint for precipitation hardening stainless steel pipes according to claim 1, wherein in step S2, the heat is preserved at 915-1055 ℃ for 0.5-1 h when the solution is completely treated, so that all alloy elements are completely dissolved in austenite to form a uniform single-phase solid solution.
  3. 3. The method for surface composite strengthening of a precipitation hardening stainless steel high-pressure pipe quick connector according to claim 2, wherein in step S2, the hardness after oil quenching to room temperature is HRC 32-38.
  4. 4. The method for surface composite strengthening of a rapid joint for precipitation hardening stainless steel pipes according to claim 3, wherein in the step S2, the cooling speed is 20-50 ℃ per second, the oil temperature is 50+ -10 ℃, and the supersaturated austenite is completely transformed into low-carbon lath martensite after oil quenching to form a uniform supersaturated martensite structure.
  5. 5. The method for compositely strengthening the surface of the quick joint of the precipitation hardening stainless steel high-pressure pipe according to claim 1, wherein in the step S3, when the aging treatment is carried out under vacuum or protective atmosphere, the temperature is kept at 500-600 ℃ for 3-4 h, the static air is cooled to room temperature after the furnace is taken out, the hardness after the aging treatment is HRC 35-48, the elongation is more than or equal to 12%, the area shrinkage is more than or equal to 45%, and the fracture toughness is higher than or equal to 45% 。
  6. 6. The method for composite strengthening of the surface of a quick joint of a precipitation hardening stainless steel high-pressure pipe according to claim 1, wherein in the step S5, spherical shots are used for multistage shot blasting, deep lamination stress is introduced by large shots first, and then surface roughness is reduced by small shots, and the surface peaks are flattened and the roughness is reduced by fine polishing, vibration polishing with low speed and low pressure, magnetorheological polishing or mechanical precision polishing after shot blasting.
  7. 7. The method for surface-compositely strengthening a quick joint of a precipitation hardening stainless steel high-pressure pipe according to claim 6, wherein in the step S5, stainless steel ball-shaped shots or ceramic ball-shaped shots of HRC 50-60 are adopted in the shot blasting treatment, the diameter of the big shots is 0.25-0.45 mm, the diameter of the small shots is 0.05-0.25 mm, the shot blasting strength is 0.15-0.3 mmA (N), the shot blasting coverage is more than or equal to 200% -400%, the shot blasting angle is vertical incidence, and the shot blasting distance is 100-300 mm.
  8. 8. The method for surface-composite strengthening of a rapid pipe joint of precipitation hardening stainless steel according to claim 6, wherein in step S5, the reduced roughness Ra is less than 0.2 μm to form a better bonding force and a uniform residual compressive stress layer in cooperation with the coating.
  9. 9. The method for reinforcing the surface of a quick joint of a precipitation hardening stainless steel high-pressure pipe according to claim 1, wherein in the step S5, the step is classified cleaning, firstly, an alkaline water-based cleaning agent is adopted to ultrasonically clean 10-15 min at 20-30 kHz and 60-70 ℃, then deionized water, a weak acid cleaning agent or a neutral cleaning agent is adopted in sequence, 5-10 min is ultrasonically rinsed at 40-80 kHz and 50-60 ℃, then deionized water is adopted to ultrasonically and finely clean 5min at room temperature and >80 kHz, finally, the step is adopted to ultrasonically soak 2-3 min in 70-80 ℃ deionized water, and the step is dried.
  10. 10. The method for surface composite strengthening of a rapid joint of a precipitation hardening stainless steel high-pressure pipe according to claim 1, wherein in step S6, the PVD process temperature is 250-370 ℃; when the Cr/CrN coating is adopted, after online treatment in a PVD vacuum chamber, cr metal bonding layer deposition is carried out, then CrN transition layer deposition is carried out, wherein the thickness of the Cr metal bonding layer is 0.1-0.3 mu m, the thickness of the CrN transition layer is 3-6 mu m, and the total thickness of the coating is 3.1-6.3 mu m; when the Cr/CrN/CrCN coating is adopted, after online treatment in a PVD vacuum chamber, cr metal bonding layer deposition is firstly carried out, then CrN transition layer deposition is carried out, and finally CrCN functional layer deposition is carried out through a gradient method, wherein the thickness of the Cr metal bonding layer is 0.1-0.3 mu m, the thickness of the CrN transition layer is 1-3 mu m, the thickness of the CrCN functional layer is 2-3 mu m, and the total thickness of the coating is 3-6 mu m.

Description

Surface composite strengthening method for precipitation hardening stainless steel high-pressure pipe quick connector Technical Field The invention relates to the technical field of stainless steel surface strengthening, in particular to a method for compositely strengthening the surface of a quick connector of a precipitation hardening stainless steel high-pressure pipe. Background The high-pressure pipe quick connector is an important basic component in an aviation hydraulic system, and realizes quick connection or disconnection of a pipeline through an internal sealing structure and an external locking mechanism, the performance and the quality of the high-pressure pipe quick connector directly influence the operation effect and the safety of the hydraulic system, and the high-reliability performance of the high-pressure pipe quick connector has important significance on the service life of an aircraft. The high-pressure pipe aviation quick connector needs to bear a large load in the working process, has excellent wear resistance, corrosion resistance, impact resistance and other characteristics, is suitable for various complex environments, and therefore has high requirements on high-pressure resistance, wear resistance, corrosion resistance, fatigue resistance and surface quality of the high-pressure pipe quick connector. Surface strengthening is an effective means for improving the high pressure resistance, wear resistance, corrosion resistance and fatigue resistance of the high pressure pipe quick connector. Current surface strengthening techniques mainly include low temperature gas nitriding/nitriding, electroplating (e.g., hard chrome), laser surface alloying/quenching, shot peening, and PVD coating. The low-temperature gas nitriding/nitriding can improve the surface hardness, has better wear resistance and fatigue resistance, can form chromium nitride, reduces the chromium content on the surface, damages corrosion resistance, is unfavorable for passing an acid/damp-heat test, has the characteristics of high hardness and wear resistance, has hydrogen embrittlement risk, is easy to become a corrosion starting point, has poor environmental protection, can cause galvanic corrosion in an acid environment, has excellent performances of high hardness, pressure resistance, wear resistance and the like, can change the substrate performance in a heat affected zone, has limited treatment area and poor corrosion resistance, can improve the fatigue strength by shot peening strengthening, introduces compressive stress, does not change the chemical composition of the surface, has limited hardness improvement, has small direct contribution to high pressure resistance and corrosion resistance, and has unfavorable wear resistance due to surface roughness. The PVD coating is a compact ceramic layer, has high hardness and bonding strength, has the hardness reaching 2000-3000 HV above (such as CrN, tiN, tiAlN, DLC, and the like), can greatly improve the surface pressure resistance, wear resistance and plastic deformation resistance, meets the high pressure resistance requirement, has excellent corrosion resistance, is compact and smooth, is favorable for wear resistance and mildew resistance, is low-temperature process, has the temperature of 200-500 ℃ generally and is far lower than the aging temperature (about 480-620 ℃) of precipitation hardening stainless steel, the matrix is not excessively aged and softened or deformed, the mechanical property of the matrix is perfectly maintained, and is environment-friendly, free of hydrogen embrittlement risk (compared with electroplating), and meets the environmental protection requirement. However, the pressure-resistant compact ceramic layer PVD coating (such as nitride, oxide and carbide coating) has the characteristics of larger brittleness, high internal stress and the like, and the matrix has larger hardness gradient and stress gradient, so that the bonding force with a group is smaller, and the fatigue resistance and the high pressure resistance are reduced. Therefore, the existing single surface strengthening treatment mode does not meet the surface treatment of the precipitation hardening stainless steel high-pressure pipe quick connector with high requirements on high pressure resistance, wear resistance, corrosion resistance, fatigue resistance and surface quality. Disclosure of Invention The invention aims to provide a surface composite strengthening method for a quick joint of a precipitation hardening stainless steel high-pressure pipe, which can realize high-quality surface strengthening treatment for the quick joint of the precipitation hardening stainless steel pipe, meet the reliability performance requirements of the quick joint of the precipitation hardening stainless steel pipe under extreme composite working conditions (high pressure, high wear resistance, severe corrosion conditions), and effectively solve the problems of short service life, insufficie