What are the differences of gr2 and gr12 titanium? Here below we will discuss this question from serveral aspects.
1) First of all, from the chemical composition
GR2：
The main component of Gr 2 is titanium (Ti), and the allowance contains a small amount of impurities, such as iron (Fe) 0.30%, carbon (C) 0.10%, nitrogen (N) 0.05%, hydrogen (H) 0.015%, and oxygen (O) 0.25%. Gr 2 is an industrial pure titanium, and its titanium content is usually greater than 99.2%.
Gr12：
Gr 12 is a corrosion-resistant titanium alloy and contains 0.3% molybdenum (Mo) and 0.8% nickel (Ni) and Gr 12 is a near α titanium alloy, significantly different from the pure titanium composition of Gr 12.
2) Second, from the Physical and chemical properties
Gr2：
The Gr 2 density is about 4.51g / cm³, which is lighter than the steel but of similar strength. Gr 2 is excellent in a variety of corrosion media and has excellent corrosion resistance. Gr 2 has good weldability and is suitable for various welding methods.
Gr12：
Gr 12 has good corrosion resistance, especially for high temperature, low PH chloride, or weak reducing acids.
Gr 12 has excellent mechanical properties and processing properties, which is suitable for the manufacture of various structural parts and components.
Specific examples:
Industrial pure titanium shows excellent corrosion resistance in room temperature ammonium chloride solution, but in high temperature and high concentration of ammonium chloride solution. A chemical plant, which used an ammonium chloride evaporator made of pure titanium, has had to be scrapped after only eight months of operation due to severe corrosion. This is a large evaporator with a diameter of 1000mm and a length of 5000mm, ammonium chloride concentration of 15% -20%, operating temperature of 110℃ -120℃, pH value between 4.0 and 6.0, and the final product is ammonium chloride crystal.
The tube plate, tube bundle and shell of the pure titanium evaporator are all made of Gr 2 industrial pure titanium, and its impurity content is strictly controlled within a certain range. However, within less than 8 months of operation of the equipment, the welds at the edge of the pipe and the middle heating chamber have been seriously corroded. The whole inner side of the lower vertebral body also suffered from comprehensive corrosion, and appeared local penetration phenomenon, corrosion pit up to 6mm deep, 80mm-100mm wide. This fact indicates that industrial pure titanium is not applicable in high temperature and severe crevice corrosion can occur. To deeply explore the causes of corrosion, the researchers performed a metallographic and SEM analysis of the corrosion site. Alographic analysis showed that the tissue at the corrosion site did not change abnormally, and no hydride produced by gap corrosion was found. SEM analysis found that the corrosion surface was honeycomb, but no cracks existed. Elemental energy spectrum analysis shows that the corrosion area contains a lot of chlorine elements, and the titanium in the corrosion area obviously has hydrogen absorption phenomenon. These results show that the corrosion products contain a large amount of chloride ions, showing the typical crevice corrosion characteristics. To fix the corrosion problems and improve the life of the equipment. They first cleared the accumulation and installed a titanium spray tube under the lower tube plate to reduce scaling. At the same time, they also made the structural improvement of the lower cone flange junction, increased the length of the transition section and formed a smooth large radius transition angle, in order to eliminate the accumulation and effusion, and avoid the effect of liquid stagnation flow dead corners and pits. These improvements significantly improved the mobility of the ammonium chloride solution, causing the equipment to corrode after 16 months of operation, and doubled the service life compared with the original equipment.
However, a more fundamental solution is to switch to Gr 12 titanium alloy. Gr 12 titanium alloy is a Ti-0.3Mo-0.8Ni alloy whose composition and impurity content are strictly controlled. Operating practice shows that the evaporator made with Gr 12 titanium alloy is completely safe and reliable in high temperature and high concentration of ammonium chloride solution, without any crevice corrosion phenomenon. Although the price of Gr 12 titanium alloy material is slightly higher than that of industrial pure titanium, its service life is more than 15 times longer than that of industrial pure titanium. Therefore, from an economic perspective, the use of Gr 12 titanium alloy to manufacture the ammonium chloride evaporator is very cost-effective.
The application of Gr 12 titanium alloy in ammonium chloride evaporator has achieved remarkable success. It not only solves the problem of gap corrosion of industrial pure titanium in high temperature and high concentration of ammonium chloride solution, but also significantly improves the service life and economic benefit of the equipment. With the continuous development of science and technology, Gr 12 titanium alloy is expected to be widely used and promoted in more fields.
What kind of gr12 Titanium material can be used to produce evaporator?
There are many kinds of gr12 titanium material products used to produce a evaporator, such as gr12 titanium plates, Gr12 titanium rods, titanium flanges, titanium pipe fittings, titanium bolts and nuts etc. Etermetal is your one-stop titanium supplier of titanium metal products. Please feel free contact us when you need titanium for your project.
