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[Titanium joints welded with laser and infrared techniques: comparative analysis of its microstructure].

BACKGROUND
Aim of the study is to compare microstructure of Titanium joints soldered with Laser and Infrared methods by performing SEM analysis, metallography and microhardness evaluation.


METHODS
Wax specimens were separated in the middle area corresponding to the joint region, machined and then soldered. 40 Titanium samples were fused and divided in 2 groups of 20 samples each. First group was soldered by laser welding, second one by infrared brazing. SEM analysis and standard metallography were carried out at joined areas and unsoldered surfaces. Microhardness test was performed on longitudinally sectioned samples with 150 g load for 15 second up to 7 mm distance from the joined area.


RESULTS
SEM photomicrographs revealed for group 1 a homogeneous metal-joint interface, without microporosities; for group 2 exhibited a distinct demarcation of metal joint interface. Metallography evaluation showed for laser joined samples only the presence of Titanium; infrared joined samples showed in soldered regions also Ni and Cu. Microhardness values detected at the joined surfaces seem to be higher for both considered groups.


CONCLUSIONS
Laser joining method with exclusive presence of Titanium seems to be ideal for monometallism; both techniques exhibited microstructural changes in the heated surface layer.