Methods to improve the quality and performance of the titanium sheet surface

A notable feature of titanium sheet is corrosion resistance, which is due to its affinity for oxygen is particularly large, can generate a dense oxide film on its surface, can protect the titanium against corrosion, in acidic, alkaline neutral salt solution and oxidizing medium has good stability, better than the existing stainless steel and other commonly used non-ferrous metal corrosion, even with platinum Bimei. Titanium is good or bad quality largely depends on the smelting process, including the chemical composition of titanium, titanium water cleanliness (gas, harmful elements, inclusions) and slab quality (segregation, decarbonization and surface condition) , these aspects is the critical control point smelting operations. In addition, industrial titanium also requires sufficient hardenability to ensure that the entire cross section of the spring to obtain uniform microstructure and mechanical properties. The main reason is that fatigue cracks of titanium oxide inclusions, and the class D inclusions on the fatigue life of the harm is greater than Class B inclusions. Therefore, foreign titanium plants and automobile plants in industrial titanium oxide inclusions put forward higher requirements, such as the Swedish SKF standard titanium oxygen content of less than 15 × 10-6, Class D inclusions below the Class B Inclusion thereof. Especially Al2O3 and TiN inclusions of titanium spring fatigue life damaging. For the production of high quality titanium industry, in the past usually an electric furnace - vacuum arc remelting ESR or other special smelting method.
Titanium is often used to make forging blank shape and dimensions close to the product, and then only for heat treatment and final machining. Casting temperature and the degree of deformation is a fundamental element of the resolution titanium arrangements function. Heat treatment of titanium blank with heat treatment of steel products factory is not the same, can not afford to arrange titanium resolution effect. Thus, the process of standard titanium products factory forging blank final important step has a unique effect. In order to make the rough titanium products factory forging together can achieve high strength and ductility, it is necessary that the entire amount of deformation of the blank is not less than 30%, deformation temperature does not exceed the phase transition temperature, and the temperature and the degree of deformation should strive throughout You can make the blank deformation spread evenly. Titanium products factory rough forging arrangements and functional uniformity of the stainless steel forgings. In metal strenuous activity area, after recrystallization heat treatment, its low times as vague crystal, fine grain high power axis is like; in difficult deformation zone, because of the small amount of deformation or no deformation, the arrangements often save the situation before the deformation. Thus forging some important blanks titanium products factory parts (such as compressor disks, blades, etc.), in addition to control of TB less distortion temperature outside and the appropriate degree of deformation, the rough handling of the original arrangement is very important, otherwise, coarse grain arrangement or some shortcomings will be inherited to the forging, heat treatment and after that they can not be eliminated, will lead to forging void.
Titanium surface reaction layer is the main factor affecting the physical properties of titanium, titanium rolling after annealing is completed required, which produces an oxide layer through the explosion of an alkali pickling method to remove the surface reaction layer of titanium.
1. Explosion base: What is critical base? Explosion alkali alkali solution that is in titanium products into boiling to the surface oxide layer reaction to the original titanium, thereby allowing subsequent pickling operation becomes possible. They use the product as a foam base, it is a white crystalline powder, soluble in water and dilute alkali solution; insoluble in alcohol and acid, alkaline aqueous solution.
2. Pickling: pickling quickly titanium surface reaction layer is completely removed, and no contamination of other surface elements. HF-HNO3 acid wash system is mainly used for titanium and titanium rods, titanium wire, titanium tube pickling, HF-HNO3 acid wash small quantity of hydrogen absorption lines can be controlled to reduce the concentration of HNO3 hydrogen storage, and the surface for bright treatment, the HF concentration is generally about 3% to 5%, the concentration of HNO3 is appropriate about 15% to 30%.