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Soo-Young Lee, Ik-Tae Chang Seong-Joo Heo, Soon-Ho Yim
이수영, 장익태, 허성주, 임순호

The use of pure titanium and titanium alloys have been increased recently in fixed, removable
prosthodontics and implant fields as a framework. But when they were used for superstructures
of implant or metal framework of removable prosthesis, welding is necessary to reconnect the frac-
ture site to control the casting distortions. To overcome the difficulties in soldering the titanium
due to high oxidation property, much effort have been devoted.
In this study,  some of mechanical properties were compared between pure titanium and Ti-6Al-
4V alloy by usingl aser welding, electron beam welding technique and tungsten arc welding. Mechanical
properties such as tensile strength, yield strength, elongation and microhardness were measured.
And, in order to compare the effect of welding site and surrounding metal tissue according to
the welding condition, SEM photographs were taken and element distribution was observed by
Wave Dispersion Spectroscopy.
Through analyses of the data, following results were obtained;      
1. In items such as tensile strength, yield strength and elongation according to the welding tech-
niques of pure titanium, only tungsten arc welded group showed significant lower value than
other groups(P<0.05).
2. In items such as tensile strength and yield strength according to the welding techniques of Ti-
6Al-4V alloy, control group and tungsten arc welded group showed significant difference among
all the groups(P<0.05).
3. Ti-6Al-4V alloy exhibited significantly greater elongation than control group when the laser weld-
ing method and electron beam welding method were used, and elongation showed increasing
4. Pure titanium specimens exhibited increasing tendency of microhardness regardless of the weld-
ing  technique  applied,  and  especially  tungsten  arc welded  group  demonstrated  a  great
increase of microhardness than parent metal.
5. There was no hardness change in laser welded group and electron beam welded group of  Ti-
6Al-4V alloy, but in tungsten arc welded group, hardness changed greatly from parent met-
al to weld seam.
6. Through the metallographic examination and scanning electron microscopy, laser welding caused
central fusion and recristallizations were formed and tungsten arc welding caused localized fusion
to 0.3 - 0.7mm from the surface.

* Keywords: Titanium, Titanium alloy, Laser, Electron beam, Tungsten arc, Welding

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