In 1940, W.J. Kroll, a scientist from Luxembourg, made pure titanium by reducing TiCl4 with magnesium. Since then, the magnesium reduction method (also known as Claudel method) and the sodium reduction method (also known as Hunter method) to become an industrial method of producing sponge titanium. In 1948, the United States made 2 tons of sponge titanium by magnesium reduction and started the industrial production of titanium.
In 1947, people began to smelt titanium in the factory. That year, the output was only 2 tons. Production soared to 20,000 tons in 1955. In 1972, the annual output reached 200,000 tons. The yield strength of titanium is higher than steel, and its weight is almost half the same volume of steel, titanium slightly heavier than aluminum, but its yield strength is 2 times larger than aluminum. The specific strength of titanium than aluminum and steel, modulus and aluminum, steel is very close. In the space rocket and missiles, a large number of titanium instead of steel. According to statistics, the annual titanium used for space flight in the world has reached over 1,000 tons. Very fine titanium powder, or a good rocket fuel, so titanium is known as the universe metal, space metal.
Titanium easily react with the air at high temperatures, but the melting point of up to 1668 ℃. At room temperature, titanium is not afraid of aqua regia and dilute nitric acid corrosion, but not resistant to more than 5% concentration of sulfuric acid and 7% hydrochloric acid corrosion. Titanium is not afraid of water at room temperature, it was a titanium sink to the seabed, five years later took a look, the top of the sticky of many small animals and plants, but did not rust, is still twinkling.
People started using titanium to make submarines - titanium submarines. Due to the very strong titanium that can withstand high pressure, this submarine can sail deep in the depths of 4,500 meters.