How To Solve The Problem Of Titanium Plate Discoloration？
Nov 06, 2025
Leave a message
I.Classification and Mechanism of Core Causes of Titanium Plate Discoloration
Titanium is unstable thermodynamically but stable kinetically.The naturally formed oxide film (TiO₂) on its surface is crucial for ensuring corrosion resistance. When this oxide film is damaged or undergoes changes in composition and structure, discoloration occurs. The main causes can be divided into the following four reasons:
1.Abnormal Growth or Composition Change of Oxide Film
In high-temperature environments (such as welding, heat treatment, and high-temperature service), the surface oxide film of titanium platestransforms from dense nano-scale TiO₂ to loose low-valent oxides like TiO and Ti₂O₃. The differences in optical properties of these oxides lead to color changes - low-temperature oxidation mostly presents pale yellow or golden yellow, while high temperatures may result in blue, purple, or even black.
2.Chemical or Electrochemical Corrosion Caused by Contamination
Local corrosion will occur in humid,acid-base media, or electrochemical environments, if the surface of titanium plates is contaminated with oil, dust, salt, metal ions (such as Fe³⁺, Cu²⁺), etc.,,
3.Oxide Film Damage Due to Mechanical Damage
During processing, transportation, and installation, if titanium plates are subjected to mechanical actions such as scratching, collision, or friction, the surface oxide film will be directly damaged. The exposed fresh titanium substrate will re-oxidize, and the newly formed oxide film will have inconsistent thickness and structure with the original one, resulting in local darkening or striped/punctate discoloration marks.
4.Long-term Erosion by Environmental Media
In special service environments, titanium plates are eroded by targeted media: acidic environments (such as sulfuric acid, hydrochloric acid) dissolve the oxide film; alkaline environments (such as sodium hydroxide solution) trigger hydroxylation reactions of the oxide film; fluoride-containing media (such as hydrofluoric acid) directly react chemically with titanium (Ti + 6HF = H₂TiF₆ + 2H₂↑), completely destroying the oxide film
.
II.Systematic Solutions for Titanium Plate Discoloration
To address the different causes of titanium plate discoloration, a systematic strategy of "prevention first, repair as supplement, and long-term protection" should be adopted, forming a closed loop from source control, process management to post-treatment:
Source Control: Optimize Production and Processing Processes
Strictly control high-temperature processing parameters: Use argon shielded welding (TIG welding, MIG welding) for welding, ensuring the argon purity in the welding area is ≥99.99% to avoid titanium contact with air and nitrogen at high temperatures; control the furnace atmosphere to be inert gas or vacuum during heat treatment, with the temperature not exceeding 600℃ (if high-temperature treatment is required, subsequent oxide film repair is necessary), and maintain a uniform cooling rate to reduce gradient growth of the oxide film.
Clean production and pollution prevention: Thoroughly remove surface oil (using alkaline degreaser for ultrasonic cleaning) and dust (purging with high-pressure clean gas) before titanium plate processing; avoid direct contact with easily contaminating metals such as carbon steel and copper; use special or pre-cleaned processing tools; keep the production environment dry and clean to prevent residual salt, acid, and alkali media.
To optimize mechanical processing: During processing,adopt high-precision cutting and grinding tools to reduce scratches and friction ; Select chlorine-free cooling fluids dedicated for titanium as cutting fluids to avoid chloride ion contamination; During transportation and storage,use wooden pallets or plastic film for packing to prevent collision damage; Store in a well-ventilated and dry environment away from corrosive substances.
ruihang Group
Baoji Ruihang Elaborate Materials Group was established in 2013, with Shaanxi Baoyuan Special Materials Technology Co., Ltd. and Shaanxi Ruihang Elaborate Materials Import and Export Co., Ltd. as its subsidiaries. The main products include titanium and titanium alloy rods, wires, titanium and titanium alloy thin plates, medium and thick plates, titanium alloy forgings, etc. The monthly production capacity of titanium and titanium alloy rods and wires is 600 tons, and the annual spot inventory of plates is over 300 tons. It is a comprehensive enterprise integrating R&D, production, and sales. Its high-quality and strict production processes and quality control system ensure the stable and reliable quality of titanium plates, as well as professional after-sales service to solve all problems encountered by customers.
2. Discoloration Repair: Targeted Treatment of Discolored Areas
Effective targeted treatments for discolored areas include chemical cleaning, mechanical grinding, and electrochemical passivation. The repair of titanium plate discoloration should select solutions based on the causes of discoloration. For example, discoloration caused by mechanical damage cannot rely solely on chemical cleaning, but should be combined with grinding and passivation.
3. Long-term Protection: Strengthen Protection Measures During Service
Surface coating protection: For titanium plates serving in harsh environments (such as marine, acid-base media), plasma-sprayed Al₂O₃, TiO₂ ceramic coatings or physical vapor deposition (PVD) TiN coatings can be used to form a double protective barrier, isolating environmental media from contact with the titanium substrate and fundamentally avoiding oxidative discoloration.
Regular inspection and maintenance : Adopt regular visual inspections of titanium plates in service and promptly clean local discoloration;For humid and corrosive environments, clean the surface with neutral cleaning agents every 6-12 months to remove salt and contaminants.Use ultrasonic testing or eddy current testing to promptly detect oxide film damage or internal corrosion hazards.
Optimize service environment: Avoid long-term service of titanium plates in high-temperature (>600℃), high-chloride, high-fluoride, or strong acid-base environments as much as possible. If unavoidable, take isolation measures (such as lining, sealing protection) to reduce direct contact between media and titanium plates.
Titanium plate discoloration is essentially an external manifestation of the damaged integrity and uniformity of the surface oxide film. In practical applications, personalized prevention, control, and repair plans should be formulated based on the specific processing scenarios and service environments of titanium plates to maximize the performance of titanium materials.