what is grade 5 titanium
summarize
Grade 5 titanium alloy is a medium-strength α-β two-phase titanium alloy containing 6% of the α-stabilizing element AI and 4% of the β-stabilizing element V. The alloy has excellent all-around properties and is most widely used in the aerospace and aviation industries. The alloy has a long working temperature of up to 400°C. In the aerospace industry, it is mainly used in the manufacture of engine fan and compressor disks and blades, as well as important load-bearing components such as beams, joints and spacer frames in the structure of aircraft.
The main semi-finished products of Grade5 titanium alloys are bars, forgings, plates, sheets, profiles and wires. The alloy is mainly used in the annealed condition and can also be strengthened to some extent by solid solution aging, however the hardened cross section is generally not more than 25mm.
The alloy has good process plasticity and superplasticity and is suitable for a wide range of pressure machining and forming. The alloy can also be welded and machined in various ways.
Specifications
| Grade 5 titanium round bar |
AMS 2631, AMS 4928, AMS 4965, AMS 6930, AMS 6931, AMS-T-9047 ASTM B348 ASME SB-381 |
| Grade 5 titanium Rectangular bar |
AMS 4928, AMS 4965, AMS 6930, AMS 6931, AMS-T-9047 ASTM B348 |
| Grade 5 titanium sheet |
AMS 4911, AMS-T-9046 ASTM B265 Gr 5, ASTM F1472 EN 10204 3.1 |
| Grade 5 titanium sheet |
AMS 2631, AMS 4911, AMS-T-9046 ASTM B265 Gr 5 EN 10204 3.1 |
| Grade 5 titanium block |
AMS 4928, AMS 6931, AMS-STD-9047 ASTM B348 |
Grade5 titanium Chemical composition
|
Chemical Composition (WT%) |
||||||||||
|
Requirement
|
Ti |
Al |
V |
Fe |
C |
N |
O |
H |
Residual element |
|
|
Remainder
|
≤ |
≤ |
≤ |
≤ |
≤ |
≤ |
≤ |
Each |
Total |
|
|
5.5-6. 75 |
3.5-4.5 |
0.40 |
0.08 |
0.05 |
0.2 |
0.015 |
≤0.10 |
≤0.40 |
||
Grade5 Titanium Alloy Heat Treatment System
1) Annealing
Plate: 700-850 ℃, 0.5-2h, air cooling; bar and forgings: 700-800 ℃, 1-2h, air cooling.
(2) vacuum annealing
700-800 ℃, 0.5-2h, furnace cooling to 200 ° C or less allowed out of the air-cooled. Absolute pressure in the furnace should not be greater than 0.09Pa.
(3) solid solution treatment
910-940 ° C, 0.5-2h, water quenching.
4)Ageing
520-550°C, 2-4h, air cooling.
5)Stress-relief annealing
Complete stress relief annealing: 600-650°C, 1-4h, air cooling; incomplete stress relief annealing: 500-600°C, 0.5-3h, air cooling. Stress relief annealing can be carried out in the air furnace or vacuum furnace.
Gr5 melting and casting process
Ingots should be melted in vacuum self-consuming electrode arc furnace more than twice. Material for engine rotor parts should be melted three times. Alloying element V is added as A1-V intermediate alloy. The welding of self-consumption electrode is strictly prohibited to use tungsten argon arc welding, and argon gas protection plasma welding method is adopted.
Gr5 Application Overview
Gr5 titanium alloy in the country is the early 1960s began to develop and produce, is now widely used in the manufacture of aero-engine fan and compressor disk and blade, as well as aircraft structure of a variety of load-bearing beams, frames, joints and fasteners and so on.
Gr5 special requirements
1)Initial α-phase quantity
The mechanical properties of Gr5 alloy are closely related to the quantity and morphology of primary α-phase. Generally speaking, the more primary α-phase content, the better the room temperature tensile plasticity and fatigue properties; the less primary α-phase, the better the high temperature durability, creep and fracture toughness. In order to obtain excellent overall performance, it is usually desirable to keep the primary α-phase content in the range of 15-50%. If the primary α-phase content exceeds this range, it is permissible to add a high-temperature solid solution treatment, i.e., a holding time of 30-60°C below the β-transition temperature for 1 h, followed by air or water cooling, before normal annealing. When the initial α-phase content is too small, only through the re-thermal deformation in the two-phase region to improve the initial α-phase content.
2) Effect of oxygen content
With the increase of oxygen content, Gr5 alloy tensile strength increased significantly, tensile plasticity and fracture toughness decreased sharply. High oxygen content also leads to poor welding performance. Therefore, the oxygen content should be kept at a low level while maintaining the strength level. Especially for low-temperature work in a variety of containers, should be used w (o) ≤ 0.13% of Gr5 alloy materials.
3)Contact corrosion
When Gr5 titanium alloy parts in contact with aluminum alloy and structural steel parts, especially in certain corrosive media conditions, aluminum alloy and structural steel parts due to the electrode potential is more negative, as the anode of the contact dipole, will be subject to accelerated corrosion and destruction. Therefore, between Gr5 titanium alloy parts and aluminum alloy or structural steel parts, protective measures should be taken such as padded anti-corrosive contact tape, etc. Gr5 alloy parts are strictly prohibited from contacting with parts or tools made of lead, zinc, cadmium, tin, silver, bismuth and other metals.
(4) Microscopic corrosion damage
Gr5 alloy due to wear resistance is poor, when the parts occur micro-abrasion, will cause a rapid decline in fatigue strength. In order to reduce micro-abrasion, Gr5 alloy parts and other metal parts between the mating surfaces, should be coated with grease, paint, or Gr5 alloy parts surface anodizing.
In order to ensure the reliability of Gr5 alloy parts in the process of use, for the manufacture of pressurized gas turbine discs, blades and aircraft structural components with the bar, forging billets, free forgings and die forgings, must be ultrasonic flaw detection. Aero-engine with die forging flaw detection, generally using a flat bottom hole diameter of 0.8mm standard sample block; aircraft structure with die forging flaw detection, generally using a flat bottom hole diameter of 1.2mm standard sample block.
Antioxidant properties of Gr5
When Gr5 titanium alloy is heated for a long time below 430℃, a very thin and protective oxide film is formed. As the heating temperature increases, the oxide film thickens and becomes less protective. The thickness of the oxide film reaches 25μrn after heating at 700°C for 2h. A sparse oxide layer is formed at temperatures above 800°C. The thickness of the oxide film reaches 25μrn after heating at 1000°C for 1h. After heating at 1000°C for 1h, the thickness of the oxide layer reaches 0.65mm.
Gr5 welding performance
(1) Gr5 alloy can be welded by argon arc welding, spot welding, brazing, electron beam welding and plasma welding. The strength of welded joints is basically equivalent to that of the base metal.
(2) Gr5 alloy after welding at 550-650 ℃ for stress relief annealing, can eliminate 70% -80% of the welding stress. Stress relief annealing of plate parts after welding is best carried out in a vacuum furnace or protective atmosphere furnace.
(3) Gr5 alloy has good diffusion connection characteristics. Connection process is completed in a vacuum. Typical diffusion connection process parameters: heating temperature of 820-1040 ℃, pressurized pressure of 35-70MPa, holding time of 0.5-6h.
Parts heat treatment process
(1) semi-finished products or parts annealing, insulation time depends on the section thickness. Cross-section thickness less than or equal to 10mm, the holding time does not exceed 30min; 11-50mm for 30-60min; greater than 50mm for 1-2h.
(2) parts heat treatment selection of various types of electric furnaces, the furnace must be thoroughly cleaned before processing. Gas or oil furnace heating, the furnace atmosphere must be strictly controlled to maintain a micro-oxidizing atmosphere, but also pay attention to do not make the combustion nozzle directly to the parts.
(3) vacuum annealing should be removed before the surface of the parts of the oxide skin and oxygen-rich layer, before entering the furnace, but also carefully de-oiled. Complex shaped parts vacuum annealing must be fixed with fixtures to reduce parts deformation. Into the furnace parts are best filled with pre-degassed non-oxidized titanium chips to prevent parts oxidation.
Surface treatment process
(1) In order to improve the fatigue strength of titanium alloy parts can be surface shot peening. Generally use the diameter of 2-5mm steel shot, can produce about 785MPa surface compressive stress, surface strengthening depth of about 200μm. shot peening can significantly improve the fatigue strength of Gr5 alloy.
(2) In order to improve the wear-resistant performance of Gr5 titanium alloy, in the wear-prone parts of the parts, such as the side of the damping table of the fan blade, the use of plasma or explosion spraying method of spraying tungsten carbide, chromium carbide, and other refractory plasmonic point coating. This method can also be used for titanium alloy parts have been worn parts of the repair.
(3) In order to avoid abrasion and bonding of titanium alloy parts in the work, in the friction contact and thread combination of parts, should be anodized, chromium-plated, chemical nickel-plated or nitriding treatment.
Cutting and grinding performance
(1) Gr5 alloy due to poor thermal conductivity, high chemical activity, cutting and processing at the tip of the temperature rises faster, easy to cause tool wear, should pay attention to the reasonable choice of tool materials and processing parameters. The use of chlorinated coolant can extend tool life and improve the processing surface quality.
(2) Milling recommended high-speed steel and carbide spiral end mill. Carbide cutting tool materials should be selected tungsten carbide class, do not choose titanium carbide class. gr5 alloy cobalt deep hole is more difficult, should be designed for the processed parts special drill, choose a larger top angle. When the diameter of the drill is larger than 6mm, in order to facilitate chip removal, the cutting edge should be opened in the cutting edge part of the shoulder groove.
(3) Gr5 alloy is prone to burns, ripples and deformation when grinding. It is recommended to use green silicon carbide grinding wheels, this kind of abrasive compared with corundum and its mixed abrasives, good grinding performance, large metal removal, small power consumption. The use of medium loose grinding wheels is conducive to reducing the temperature of the grinding zone. The best choice of grinding fluid is aqueous cutting fluid.
Recommendations for the use of Gr5
It is recommended to use Gr5 titanium alloy to manufacture various beams, joints, spacer frames in the fuselage and wing structure of the airplane and disk parts and blades in the aero-engine fan and compressor. Using Gr5 titanium alloy instead of 30CrMnSiA and other structural steels can realize the weight reduction of parts by about 30%.
To learn more about the advantages of Grade 5 titanium for your projects, contact us at euros.yang@xuboti.com. We're ready to support your needs with expert advice.
