Applications
TC4 titanium alloy has a series of advantages, such as excellent corrosion resistance, small density, high specific strength, good toughness, and weldability, etc. It has been successfully applied in aerospace (figure. 4), petrochemical, shipbuilding, automobile, medicine, and other departments.[5]
Titanium alloy has been widely used in aviation, aerospace, military, chemical, medical, offshore oil mining and other fields for its outstanding performance advantages. It is known as “space metal”, “marine metal” and “smart metal”. Titanium alloy is a new type of metal structural material that plays an important role in the development of national defense high-tech weapons and equipment. It has been listed as a new type of structural metal material with strategic significance in the 21st century, which has been listed as a key development by many military powers in the world. With the sustained and rapid development of the national economy, titanium alloys have been applied in the aerospace and weaponry fields, and the demand for titanium alloys in China has increased at a rate of 20% to 30% per year.
Apart from the applications in aerospace and navigation industry, tc4 titanium alloy recently is used in the medical field prevalently. Orthopedic Surgery, for examples, titanium in the pharmaceutical industry is mainly used in the production of containers, reactors, and heaters, etc. In pharmaceutical production, equipment often contacts with hydrochloric acid, nitric acid, sulfuric acid, and other inorganic acids, organic acid and its salts, equipment due to corrosion often damage, and because of the iron ion pollution caused by steel equipment to affect the quality of the product, the use of titanium equipment can solve these problems.
Properties
Titanium alloys (figure.1) are metals containing a mixture of titanium and other chemical elements. This alloy has high tensile strength and toughness even at extreme temperatures. They are light, have excellent corrosion resistance and can withstand extreme temperatures. However, TC4 titanium alloy, as the kind of the titanium alloy, possess the most properties of the titanium alloy while this kind of special and sophisticated material has its own edge and advantages.
As for the properties of titanium alloy, the tables shown down blow demonstrate the properties of the titanium alloy in four chief aspects. And there are four groups of titanium alloys: alpha alloys, near-alpha alloys, alpha-beta alloys, and beta alloys. The alpha alloys have an HCP crystal structure while the beta alloys have a BCC crystal structure. And alpha alloys have wider use in the higher temperatures due to their creep resistance and preferred for cryogenic applications because of their good toughness at low temperatures. And figure.2 shows the phase diagram of these four kinds of titanium alloy.
In conclusion, the normal titanium alloy has many merits. It has high strength because the specific strength (strength/density) of titanium alloy is much higher than that of other metals, which can produce parts with high unit strength, good rigidity and lightweight. Aircraft engine components, skeletons, skin, fasteners and landing gear are made of titanium alloy. Secondly, titanium alloy has good corrosion resistance because that titanium alloy works in humid atmosphere and seawater, its corrosion resistance is much better than stainless steel. Besides, this alloy has a strong resistance to pitting, acid and stress corrosion and good corrosion resistance to alkali, chloride, organic chlorine, nitric acid, sulfuric acid, etc. But titanium has poor corrosion resistance to reducing oxygen and chromium salt medium.
For TC4 titanium alloy (figure. 3) the condition becomes a little different. The chemical composition of the tc4 titanium alloy is 0.10 or less C，0.30 or less Fe，0.05 or less N ，0.015 or less H，0.20 or less O，5.5 ~ 6.8 Al，3.5 ~ 4.5 V and Titanium.[4]
As for the mechanical properties of tc4 titanium alloy. Ti-6al-4v (TC4) titanium alloy TC4 material is composed of ti-6al-4v, belongs to (α+β) type titanium alloy, has good comprehensive mechanical properties. Greater than the strength.TC4 strength sb=1.012GPa, density g=4.4*103, specific strength sb/g=23.5, while the specific strength sb/g of alloy steel is less than 18. Titanium alloy has low thermal conductivity. The thermal conductivity of titanium alloy is 1/5 of that of iron and 1/10 of that of aluminum, and the thermal conductivity of TC4 is l=7.955W/m·K. 895 MPa or greater tensile strength, of specified residual elongation stress in the sigma r0.2 / MPa or greater 825, 5 (%) of 10 or higher elongation, reduction of area bits (%) of 25 or higher.
References
[1] CES Edualpack Edition 2018, Granta Design Limited 1999-2018, Titanium alloy
[2] Zheng C, Li K, Machining Process and Fatigue Test of TC4 Titanium Alloy Strain Fatigue Specimens [J] 2017
[3] C.H. Che-Haron; A. Jawaid; The effect of machining on surface integrity of titanium alloy Ti–6% Al–4% V [J] 2004
[4]Why is the strength coefficient of tc4 titanium alloy higher than that of alloy steel，Anbound，military，2018
[5] http://www.aerospacemetals.com/all-about-titanium.html ASM Aerospace Specification Metals Inc. 2501 N.W. 34th Place #B28, Pompano Beach, Florida 33069