Investigation Of Laser Welding Research Articles

Investigation of laser welding on butt joints of Al/steel dissimilar materials

Abstract Dissimilar metals of AA6013 aluminum alloy and Q235 low-carbon steel of 2.5 mm thickness were butt joined using a 10 kW fiber laser welding system with ER4043 filler metal. The study indicates that it is feasible to join aluminum alloy to steel by butt joints when zinc layer was hot-dip galvanized at the steel’s groove face in advance, and better weld appearance can be obtained at appropriate welding parameters. The joints had dual characteristics of a welding joint on the aluminum side and a brazing joint on the steel side. The smooth Fe 2 Al 5 layer adjacent to the steel matrix and the serrated-shape FeAl 3 layer close to the weld metal were formed at the brazing interface. The overall thickness of Fe–Al intermetallic compounds layers produced in this experiment were varied from 1.8 μm to 6.2 μm at various welding parameters with laser power of 2.85–3.05 kW and wire feed speed of 5–7 m/min. The Al/steel butt joints were failed at the brazing interface during the tensile test and reached the maximum tensile strength of 120 MPa.

钛合金与合金钢激光焊接工艺实验研究

钛合金与合金钢激光焊接工艺实验研究

Investigation of Laser Welding on Vehicle Safety Parts

Based on many experiments of CO2 laser welding of high strength two-sided galvanized steel thick with 1.5mm to vehicle body, joint microstructure and stress-strain curves of specimen are acquired. It has inferred theoretically relations among critical power, welding speed and focal point position under given welding technological conditions. With coaxial and side-blown protective gas, craft parameter are optimized, the laser deep melt welding may avoid effectively heat-affected zone (HAZ) softened phenomenon, as well as welded porosity may controlled effectively. The experimental result shows that hardness value in weld zone becomes low with increasing of energy input, at the same time the cracked zone of tensile specimen, the dimple size and the distribution of cross-section in welding seam are also different, tensile crack of welding seam extends to the base metal, which indicates deep penetration laser welding can effectively avoid softening of welding joints during laser welding of high strength galvanized steel.

Metallurgical Investigations of Laser Welding of AISI 304 Stainless Steel

Laser welding of AISI 304 stainless steel was carried out by pulsed Nd:YAG laser machine under different welding conditions. Geometrical shape of the joints was circular butt. Studies were focused on laser power, welding velocity, beam diameter and pulse duration. Microstructure of welded joints was investigated by optical microscopy (OM) and scanning electron microscopy (SEM). OM and SEM results show no evidence of grain growth in heat affected zone (HAZ). In addition, columnar and equiaxed grains are observed in the weld metal. Various defects such as lack of fusion, underfill, porosity, hot crack and mismatch are observed as a result of improper welding conditions. The best welding conditions to obtain minimum defects are presented.