Method for Improving Surface Quality and Performance of Titanium Plate
A notable feature of Grade 6 Titanium plate is its strong corrosion resistance. This is because it has a particularly strong affinity for oxygen and can form a dense oxide film on its surface, which can protect titanium from moderate corrosion. The neutral salt solution has good stability in neutralizing oxidizing media, and has better corrosion resistance than existing stainless steel and other commonly used non-ferrous metals, even comparable to platinum.
The quality of Grade 6 Titanium plate depends largely on the smelting process, including the chemical composition of titanium, the cleanliness of titanium water (gas, harmful elements, inclusions) and the quality of the slab (composition segregation, decarburization and surface condition ). These aspects are critical control points for smelting operations.
In addition, industrial titanium plates also require sufficient hardenability to ensure uniform microstructure and mechanical properties throughout the spring section. The main cause of fatigue cracks is oxide inclusions in titanium, and D-type inclusions are more damaging to fatigue life than B-type inclusions. Therefore, foreign titanium factories and automobile factories have put forward higher requirements for oxide inclusions in industrial titanium plates. For example, the Swedish SKF standard requires that the oxygen content in titanium is less than 15×10-6, and the D-type inclusions are lower than the B-type inclusions. matter. In particular, Al2O3 and TiN inclusions are the most detrimental to the fatigue life of titanium springs. In order to produce high-quality industrial titanium plates, special melting methods such as electric furnace-electroslag remelting or vacuum arc remelting were usually used in the past.
Die forging of titanium plate blanks is usually used to produce products of similar shape and size, and then only the final blank is heat treated and cut. Casting temperature and degree of deformation are the basic factors that determine the arrangement and function of titanium alloys. The heat treatment of the titanium plate blank product factory is different from the heat treatment of the steel, and has no effect on the arrangement of the titanium alloy. Therefore, the process standard of the last step of die forging in the factory of titanium slab products has a unique and important role.
In order to enable the die forgings of the titanium plate rough product factory to obtain higher strength and plasticity together, the total deformation of the blank must be not less than 30%, the deformation temperature must not exceed the phase transition temperature, and the temperature and degree of deformation must be evenly distributed in the deformation in the rough. Die forging layout and functional uniformity of stainless steel forgings in titanium plate rough products factory. In the violent metal active area, after recrystallization heat treatment, low magnifications are fuzzy crystals, and high magnifications are equiaxed fine crystals. In areas that are difficult to deform, the arrangement often remains as it was before deformation due to little or no deformation. Therefore, when forging some important titanium plate blank product factory parts (such as compressor discs, blades, etc.), in addition to controlling the deformation temperature below TB and controlling the appropriate degree of deformation, it is very important to control the layout of the workpiece. Original blank. Otherwise, the coarse grain arrangement or certain defects will be inherited into the forging, and the subsequent heat treatment cannot be eliminated, which will lead to the scrapping of the forging.
When using a closed die forging method to forge a titanium plate blank product, the life of the die is reduced due to the high pressure. Therefore, closed-die forging must strictly limit the volume of the original blank, which will make the preparation process confusing. Whether to choose closed die forging should be considered from the perspective of cost and process feasibility. In open die forging, the burr loss accounts for 15%-20% of the blank composition, and some technical waste (if necessary, according to the requirements of the die forging conditions) accounts for 10% of the blank composition. The relative loss of burr metal usually increases with the decrease of blank composition. For some forgings with asymmetric layout, large difference in cross-sectional area, and some difficult-to-fill forgings, the burr consumption can be as high as 50%. Although there is no burr loss in closed-die forging, the billet manufacturing process is messy and requires more transition grooves, which will undoubtedly increase auxiliary costs.
The reaction layer on the surface of Grade 6 Titanium plate is the main factor affecting the physical properties of the titanium plate. Titanium plate needs to be annealed after rolling. The generated oxide layer needs to be removed by explosive alkaline cleaning to remove the surface reaction layer of the titanium plate.
