1. Introduce
– A high-strength metal that is less than half the weight of steel and has excellent heat resistance, corrosion resistance, and biocompatibility
– It is an active metal with a strong affinity for oxygen and nitrogen and is highly reactive, oxidizing rapidly when exposed to water or air, forming a passive film on the surface
→ Due to the passive film, it has excellent corrosion resistance, second only to gold or platinum
– Commercial titanium is categorized into grades based on the content of impurities
→ Impurities : nitrogen, carbon, hydrogen, oxygen, and iron
– Ti alloying elements affect : corrosion resistance, strength, heat resistance
* Type of titanium
(1) CP (Commercialloy Pure)
– Divided into grades 1, 2, 3, and 4 according to the content of nitrogen, carbon, hydrogen, oxygen, and iron
– Titanium grades are based on classifying different properties such as tensile strength, corrosion resistance, wear resistance, thermal conductivity, etc.
– Titanium with the least impurities : Grade 1
| Type | Grade 1 | Grade 2 | Grade 3 | Grade 4 |
|---|---|---|---|---|
| Nitrogen (%) | Max. 0.03 | Max. 0.03 | Max. 0.05 | Max. 0.05 |
| Carbon (%) | Max. 0.08 | Max. 0.08 | Max. 0.08 | Max. 0.08 |
| Hydrogen (%) | Max. 0.015 | Max. 0.015 | Max. 0.015 | Max. 0.015 |
| Oxygen (%) | Max. 0.18 | Max. 0.25 | Max. 0.35 | Max. 0.40 |
| Iron (%) | Max. 0.20 | Max. 0.30 | Max. 0.30 | Max. 0.50 |
(2) Titanium Alloy
– Elements such as Al, Sn, Mn, Fe, Cr, Mo, V, etc. are added to improve the properties of Ti
– Grade 5 onwards is classified as a titanium alloy
– Typical titanium alloys include Grade 5 (6Al-4V), Grade 7 (Ti-0.15Pd), Grade 12 (Ti-0.3Mo-0.8Ni), and Grade 23 (6Al-4V Eli)
| Grade | Features |
|---|---|
| Grade 5 | Most used titanium alloy Excellent high strength and corrosion resistance |
| Grade 7 | Alloy with approximately 0.15% palladium added Excellent corrosion resistance (Physical properties are similar to Grade 2 pure titanium, but corrosion resistance is greatly enhanced by the palladium) |
| Grade 12 | Moderate mechanical properties among titanium alloys Good cold formability, weldability, and oxidation resistance |
| Grade 23 | Excellent specific strength, strength, and biocompatibility (Similar to Grade 5) |
(3) Types based on crystal structure
| Grade | Characteristics |
|---|---|
| Pure Titanium | Low strength, good corrosion resistance |
| α Alloy | Lower room temperature strength than other alloys, low temperature stable phase, good heat resistance α-stabilizing elements: Al, Sn, Zr |
| α-β alloy | Most widely used alloy, good toughness, plastic machinability, weldability, castability |
| β alloy | High strength properties are obtained by high temperature stable phase, solubilization treatment and aging β-stabilizing elements : V, Mo |
2. Property
– Strength, Specific Strength, Corrosion Resistance, Biocompatibility, Good Wear Resistance
[Ti Mechanical Properties]
| Tensile Strength (Mpa) | Yield Strength (Mpa) | Elongation (%) |
|---|---|---|
| Min. 240 | Min. 170 | 54 |
[Ti Physical Properties]
| Density (g/㎤) | Melting Range (℃) | Electrical resistivity (µΩ∙㎝) | Specific Heat (J/kg∙℃) | Thermal Conductivity (W/mK) | Coefficient of Thermal Expansion (µm/m°C) |
|---|---|---|---|---|---|
| 4.5 | 1650~1670 | 55.4 | 528 | 17 |
3. Application
– Bicycle frames, aircraft frames, implants, ship parts, heat exchangers, heating and air conditioning, submarine materials
(1) Ship parts / (2) Heating and cooling / (3) Heat exchangers / (4) Implants
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