Titanium alloy
Titanium alloy refers to a variety of titanium and other metals made of alloy metal, high strength, good corrosion resistance, high heat resistance. Titanium alloy is widely used in the production of aircraft engine compressor parts, skeleton, skin, fasteners and landing gear. Titanium is also used in rockets, missiles and structural parts for high-speed aircraft.
Titanium is an isomer, melting point is 1668℃, below 882℃, dense hexagonal lattice structure, known as α titanium; Above 882℃, it exhibits a body-centered cubic lattice structure, which is called β titanium. Titanium alloys with different structures can be obtained by adding appropriate alloying elements according to the different characteristics of the two structures. At room temperature, titanium alloys have three kinds of matrix structures, which are divided into the following three categories: α alloys,(α+β) alloys and β alloys. China is represented by TA, TC and TB respectively.
The density of titanium alloy is generally about 4.51g/cm3, only 60% of steel, some high strength titanium alloy is more than the strength of many alloy structure, so the specific strength of titanium alloy (strength/density) is much greater than other metal structure materials, can produce high unit strength, good rigidity, light parts.
Titanium is non-toxic, light, high strength and excellent biocompatibility, so it is an ideal metal material for medical use as human implants. In the United States, five β titanium alloys have been recommended for medical use, Namely, TMZFTM (Ti-12Mo-^ Zr-2Fe), Ti-13NB-13Zr, Timetal 21SRx (Ti-15Mo-2.5NB-0.2Si), Tiadyne 1610 (Ti-16Nb-9.5Hf) and Ti-15Mo, Suitable for implantation, such as artificial bone, vascular stent, etc.
TiNi alloy has good biocompatibility and there are many medical examples using its shape memory effect and superelasticity. Such as thrombosis filter, spinal orthosis bar, dental orthosis wire, vascular stent, bone plate, intramedullary needle, artificial joint,
contraceptive device, heart repair element, artificial kidney with micro pump, etc.
Titanium alloy products can be obtained by die casting and machining methods. The melting temperature of titanium alloy is very high, and the requirements for mold steel are also high. Titanium alloy machining methods are many, mainly including: turning, milling, boring, drilling, grinding, tapping, sawing, edM, etc.
Titanium alloy machining performance is also poor. Titanium alloy cutting cutting force is only slightly higher than the same hardness of steel, but most of the titanium alloy thermal conductivity is very low, only steel 1/7, 1/16 of aluminum, so the heat generated by cutting will not quickly dispersed, gathered in the cutting area, resulting in rapid cutting tool edge wear, collapse and the formation of chip nodules.
