PHYSICAL FEATURES

Titanium is a pure element: we find it in nature as oxides and it’s very common on earth’s crust: it’s the 9th element for abundance and the 3th metal to use in mechanical constructions, after Aluminium and Iron.
It’s included in the periodic table of the elements of the IV group and IV period.
The atomic number is 22 and its trend is first of all metallic, even if it’s a transiction element.

Copper Electrodes (Cu) are the priority for the heat squandering created by the electric pulse lasting 250 – 300 milliseconds.




SINTERIZATION
compaction of Titanium superior prismes undergoing a great pression united to a temperature increase equal to 70% of that fusion.
SYNCRYSTALLIZATION
Deep crossover of prismatic crystals through the union of atoms in the construction of the crystal lattice
In the whole welding cycle we can distinguish 3 phase:
1 - Approaching phase: during which there is only the application of pressure without current
2 - Welding phase: where the pressure and current are simultaneous up to the core fusion
3 - Cooling phase: where there's no current wile the pressure is maintained
COOLING PHASE
It’s also important because in this phase metal crystallizes and you need to keep it under pressure

The passing current will develope an heat as more intense as high is the present resistance,

LAW of JOULE:

Q= heat quantity expressed in calorie degrees (Cal)
J= mechanical equivalent of the big calorie expressed
Joule/Cal (1Cal=4,18x10³ J)
I= current intensity in ampere
R= electric resistance in Ohm
t= time in seconds


Pulse without Argon

Images at different enlargements of the welded joint with an only pulse without Argon a).
b) Image by back-scattering system.
c), d) e f) images by signal of secondary electrodes (after etching)
Pulse without Argon

Image SEM of the welded joint by an only pulse without argon and analysis EDS of the marked areas:
a) welding,
b) wire
Pulse with Argon

Different enlargements of the welded joint by an only pulse with Argon a).
b) Image by back-scattering method.
c), d) e f) images by signal of secondary electrodes (after etching)
Pulse with Argon

Image SEM of the welded joint by an only pulse with argon and analysis EDS of the marked areas:
a) welding, b) wire