Akademik Veri Yönetim Sistemi
Gazi University Journal of Science Part A, cilt.8, sa.1, ss.146-156, 2021 (Hakemli Dergi)
In this study, the effect of welding speed (3,
3.5, 4 m / min) and focal length (0, 1.4 mm) on the mechanical properties of
the welded structure was investigated in the overlap type joining of 1.2 mm
sheet thickness DP600 dual phase steel sheet material by fiber laser welding
method. For this purpose, tensile-shear tests were performed on the samples
joined by laser welding method, and the tensile strength and elongation amounts
were determined. Microstructure investigation and microhardness measurements of
the welded area were carried out. It is determined that weld joint shape and
penetration depth changes according to focal length distance and welding speed,
and with the maximum welding speed specimens has the minimum penetration depth.
Tensile shear strength values decreased depending on the increased welding
speed for both focal length specimens. It is observed that the microhardness results
were affected by welding speed and focal lengths. In 0 mm focal length distance
specimens’ hardness values increased according to the increased welding speed,
but for – 1.4 mm focal length distance the microhardness values decreased with
an increased welding speed. The fracture zones and fracture surface morphology
also affected by welding speed and focal distance. In 0 mm focal length, all
the specimen fractured in base metal with a ductile fracture morphology, but in
the – 1.4 mm focal length, specimens fractured from the zones which are closer
to HAZ and FZ with a brittle fracture morphology.