Titanium and its alloys

Titanium and its alloys are very suitable for use in high-speed aircraft such as aircraft, missiles, and rockets due to their low density (4.51 g/cm3), high strength (some up to 1000 MPa), high specific strength, and excellent high and low temperature performance (- 250 ℃ to 500 ℃) and fatigue resistance (fatigue limit is twice that of steel). The weight reduction effect produced by the application of titanium alloy fasteners will have a significant effect on improving the propulsion force of aircraft and spacecraft, increasing range, saving fuel, and reducing launch costs. In modern aircraft manufacturing, the connecting fasteners used in an aircraft range from hundreds of thousands to millions. Titanium alloy fasteners account for up to 90% of threaded fasteners. Titanium alloy fasteners have become the most important type of "aerospace fasteners" nowadays.

Titanium alloy fasteners have excellent corrosion resistance, especially their positive potential properties that match carbon fiber composite materials, effectively preventing galvanic corrosion of fasteners. Therefore, not only titanium and aluminum structures, but also some composite materials can be connected with titanium alloy fasteners. This characteristic is irreplaceable by any other material, which is also the rapid development of titanium alloy fasteners

ue to its better resistance to seawater corrosion than all metals, titanium has special stability in static or high-speed flowing seawater. In addition, fasteners made of titanium alloy are very suitable for applications in submarines, warships, civilian ships, and seawater desalination devices.

Industrial fields in heavily corrosive environments

In facilities and equipment related to petroleum, chemical, metallurgical, and electric power industries, fasteners and connectors not only have to withstand certain loads, but also are subjected to strong corrosion by various acid and alkali media. Working conditions are very harsh, and using titanium alloy fasteners is the best choice. Because titanium has extremely strong corrosion resistance in high-temperature and wet chlorine environments. For example, in normal temperature chlorine water, the corrosion rate of titanium is 0.000565mm/a; In chlorine water at 80 ℃, the corrosion rate is 0.00431 mm/a; In 95% wet chlorine water, the corrosion rate is 0.00096mm/a.

Titanium and its alloys are very suitable for use in high-speed aircraft such as aircraft, missiles, and rockets due to their low density (4.51 g/cm3), high strength (some up to 1000 MPa), high specific strength, and excellent high and low temperature performance (- 250 ℃ to 500 ℃) and fatigue resistance (fatigue limit is twice that of steel). The weight reduction effect produced by the application of titanium alloy fasteners will have a significant effect on improving the propulsion force of aircraft and spacecraft, increasing range, saving fuel, and reducing launch costs. In modern aircraft manufacturing, the connecting fasteners used in an aircraft range from hundreds of thousands to millions. Titanium alloy fasteners account for up to 90% of threaded fasteners. Titanium alloy fasteners have become the most important type of "aerospace fasteners" nowadays.

Titanium alloy fasteners have excellent corrosion resistance, especially their positive potential properties that match carbon fiber composite materials, effectively preventing galvanic corrosion of fasteners. Therefore, not only titanium and aluminum structures, but also some composite materials can be connected with titanium alloy fasteners. This characteristic is irreplaceable by any other material, which is also the rapid development of titanium alloy fasteners.

Common titanium fasteners mainly include: ordinary titanium bolts, high lock bolts, Eddie bolt systems, etc.

Ordinary titanium bolts: According to head type, they are divided into countersunk (100 °, 130 °) bolts, hexagon bolts, twelve point bolts, and twelve point flange bolts.Therefore, titanium alloy fasteners are the best alternative to stainless steel fasteners.

Medical and pharmaceutical production fields

Titanium alloy fasteners are increasingly used in pharmaceutical equipment, medical devices, surgical instruments, and artificial bones due to their ability to resist liquid corrosion within the human body, lack magnetism, and have good biocompatibility and are harmless to the human body.

The field of high-end sports equipment

Titanium alloy fasteners have considerable application prospects in the manufacturing of high-end sports equipment (such as golf clubs), high-end bicycles, and high-end cars. In 2010, China's titanium consumption for automobiles and motorcycles alone reached nearly 8000 tons. As the automotive industry is the largest user of fastener products, its demand accounts for approximately 18% to 20% of total fastener sales. Therefore, it is of great significance to further expand the market space of titanium alloy fasteners for automobiles.

The tensile strength of titanium alloy fasteners is generally 1000 to 1500MPa, which is equivalent to the strength level of 30CrMnSiA steel after quenching and tempering. The shear strength of titanium alloy fasteners is also of the same grade as alloy steel, but the density is only 58% of that of steel. Therefore, on advanced foreign aircraft, 30CrMnSiA steel fasteners have been basically replaced by titanium alloy fasteners. Due to its high specific strength (up to the specific strength of high-strength aluminum alloys), it has a temperature resistance of 350 ℃. A variety of titanium alloy fasteners are used for modern aircraft materials, mainly including ordinary titanium bolts, interference bolts, and special bolts.

100 ° countersunk head bolts have various groove shapes, such as Philips cross groove, high torque cross groove, three wing groove, high torque slotted groove, and so on. The rod diameter has clearance type and interference type.

High lock bolt: It is a threaded fastener that can be installed on one side, and is one of the fasteners widely used in aircraft. According to the stress, it can be divided into tensile type and shear type. The bolts have a 100 ° countersunk head and a flat protruding head, and aluminum high lock nuts are used for shear type bolts. Stainless steel nuts are used for tensile type bolts. The rod diameter is divided into clearance type, interference type, and short thread interference type. Nuts are divided into ordinary high lock nuts, sealed high lock nuts (with nylon washers inside), and self centering high lock nuts according to their use.

According to my nonferrous analysis, the production technology requirements for aviation titanium alloy fasteners are almost stringent. In addition to the requirements of high specific strength, high temperature resistance, low temperature resistance, anti-corrosion, corrosion resistance, and the pursuit of the highest possible fatigue life, it is also required to have functions such as anti loosening, self-locking, and shape memory. The progressiveness, reliability and rationality of installation and connection should all reach an ideal situation. That is, after the completion of the assembly process, the clamping force, self-locking force, and interference amount should be reliably guaranteed. The threads of titanium alloy fasteners are mostly MJ threads (metric system) or UNJ threads (British system) with enlarged circular arc bottoms and high accuracy, and their technical content is far higher than that of general-purpose fasteners.