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Electron beam melting of titanium


SE «SPC «Titan» of the E.O. Paton Electric Welding Institute of the NAS of Ukraine® developed and introduced into industrial production the technology of electron beam melting of ingots of unalloyed titanium of grades VT1-00, VT1-0, Gradel, Grade2, which is characterized by:
  • ability to use as initial charge material both titanium sponge and lump wastes of titanium production, as well as prepared chips, and here the amount of wastes used in the charge can reach 100 %;
  • elimination of expensive operation of consumable electrode compacting from the process cycle;
  • guaranteed removal of refractory nonmetallic inclusions of both high and low density;
  • production of structurally and chemically homogeneous titanium ingots of both round and rectangular cross-section from initial charge in one remelting cycle.

The following can be used as initial charge: titanium sponge of different fractions, pelletized titanium sponge, as well as titanium scrap and prepared chips.

Remelting sponge titanium pellets into an ingot of 400 mm diameter of Grade 2
Remelting uncrushed sponge titanium blocks into an ingot of 1100 mm diameter of Grade 2
Uncrushed blocks of Ti sponge
 
Crushed Ti sponge
 
Ti sponge pellets
 
Ti scrap
 

Electron beam melting of commercial titanium alloys

Fundamental studies conducted at the E.O. Paton Electric Welding Institute of the NAS of Ukraine of the processes of alloy component evaporation from the melt in vacuum and ingot solidification at EBM allow prediction of chemical composition and structure of produced ingots of titanium alloys, and enable producing ingots of guaranteed composition. Application of cold hearth allows avoiding penetration of refractory inclusions of high and low density into the produced ingots. SE «SPC «Titan» of the E.O. Paton Electric Welding Institute of the NAS of Ukraine® mastered the technology of producing ingots of titanium alloys for structural applications (3M, VT5, PT- 7M, PT-ZV, VT6, VT14, VT20, VT22, VT23, T110, etc.) and of high-temperature titanium-based alloys (VT5-1, VT3-1, VT8, VT9, VT25U, etc.).
Technology of electron beam melting allows producing titanium-based alloys with not more than 0.002 % hydrogen content and equiaxed fine grain, both in transverse and in longitudinal section of the ingot that increases technological ductility of metal during subsequent thermomechanical treatment and improves the uniformity of mechanical properties of produced semi-finished products.

Remelting titanium scrap of VT3-1 grade into an ingot of 600 mm diameter
Macrostructure of ingot of 400 mm diameter of titanium alloy H-6AMV in the transverse and longitudinal section
Producing slabs of 165x950x2500 mm size
of titanium alloy PT-3V


Production of new titanium-based alloys

SE «SPC «Titan» of the E.O. Paton Electric Welding Institute of the NAS of Ukraine® mastered the technology of producing new high-strength titanium alloy T110 (Ti-5Al-1Mo-1V—4Nb-2Fe-0.5Zr), developed at the E.O. Paton Electric Welding Institute of the NAS of Ukraine. T110 titanium alloy features of high specific strength, by which it is not inferior to high-strength alloy VT22, and increased resistance to fatigue cracking and technological ductility, allow applying it as material for protective purposes in aircraft construction. By a number of service properties, for instance, by fatigue life, T110 alloy exceeds VT22 alloy characteristics by 15-20 %.

Macrostructure of an ingot of 400 mm diameter of titanium alloy T110
Macrostructure of an ingot of 150 mm diameter
of titanium aluminide Ti-44AI-5Nb-2Cr-1,5Zr-1B

Mechanical properties of high-strength titanium alloys

Alloy σ0,2, MPa σa, MPa δ, %
Ti-6Al-4V 795 860 10
Ti—10V-2Fe-3Al 1100 1170 6
BT22 990 1080 8
T110 1060 1100 15
SE «SPC «Titan» of the E.O. Paton Electric Welding Institute of the NAS of Ukraine® gained extensive experience of producing ingots based on titanium aluminides (Ti3AI, TiAl intermetallic compounds), which have high heat resistance, thermal stability and low specific weight, making them promising materials for application in aircraft engines and other aerospace engineering products. Developed EBM technology allows producing titanium aluminide ingots with additional alloying by refractory and rare-earth elements.

Titanium aluminide ingot of 150 mm diameter
Microstructure of Ti-44AI-5Nb-2Cr-1,5Zr-1B ingot

Mechanical properties of an alloy based on titanium aluminide produced by EBM

Ti-44AI-5Nb-2Cr-1,5Zr-1B Compressive
yield
strength σ0,2
Compressive
ultimate
strength σ0,2, MPa
Bending strength σt, MPa Modulus of elasticity E, GPa
Testing temperature, °C 20 900 20 900 20 20
Cast alloy 1078 640 1660 1050 583 155


Electron beam glazing of ingot surface

Machining is traditionally performed for ingots at different stages of metal processing. Amount of wastes is usually equal to 5-15 % of treated ingot weight. To reduce metal losses, the E.O. Paton Electric Welding Institute of the NAS of Ukraine developed and introduced into production a technology of glazing by electron beams the side surface of ingots of both round and rectangular cross-section, instead of machining, and designed the respective equipment for its realization.
Technology of electron beam glazing of side surface of ingots allows removing surface defects without machining the ingot surface that increases metal yield up to 15 %, depending on ingot weight.

Glazing of an ingot of a round cross-section
 
Glazed ingot of 1100 mm diameter
 
Appearance of titanium alloy ingots: a — with glazed surface;
b — with machined surface; c — cast ingot
Glazing of an ingot of a rectangular cross-section
 
Glazed slab of 165x950x2000 mm