Stainless steel materials in boiling nitric acid solution will be due to intergranular chromium and corrosion, for nitric acid corrosion resistance of ultra-low carbon stainless steel materials, such as 000Cr25Ni20, in the boiling nitric acid solution containing metal cations, due to the high oxidation of metal cations lead to ultra-low carbon stainless steel will occur strong intergranular corrosion. Titanium has good corrosion resistance in nitric acid. The mechanism is that a protective oxide film is formed on the surface of titanium to block the interaction between the corrosion liquid and the metal matrix, so as to reduce the corrosion rate of the metal matrix. However, in high temperature concentrated nitric acid, the corrosion resistance of titanium decreases significantly due to the low density and bonding strength of titanium oxide film. The average corrosion rate of industrial pure titanium in boiling 65% nitric acid solution exceeds 1.0mm /a, which cannot meet the requirements of engineering design. In practice, Ti-Ta binary alloy is obtained by adding Ta element to Ti, which has good resistance to nitric acid.
Ti 5Ta alloy, by adding 4wt % ~ 6wt % tantalum in pure titanium to enhance the corrosion resistance of industrial pure titanium, the average annual corrosion rate of the alloy in boiling nitric acid solution is 0. 1 ~ 0.2mm/a, tensile strength of 330MPa, elongation of 23%, its shortcomings are strength, plasticity is not high, corrosion resistance slightly poor. The utility model relates to Ti-Ta-Si alloy with excellent nitric acid corrosion resistance, which forms a ternary corrosion resistant titanium alloy by adding tantalum with a weight ratio of 1% ~ 6% and silicon with a weight ratio of 0.01% ~ 0.5% to titanium. A small amount of silicon is added to inhibit the corrosion of Ti-Ta base alloy, but the inhibition effect is limited. The ductility and machining properties of Ti-Ta base materials are adversely affected by the addition of silicon element.
The uneven distribution of Ta in the alloy will cause the uneven performance of the alloy, especially corrosion resistance. The distribution characteristics of high melting point Ta inclusion and Ta in Ti-6Ta alloy casting were observed and studied in order to improve the metallurgical quality of alloy ingot casting.
