Showing 3 results for Pulsed Laser Welding
H. Ebrahimzadeh, H. Farhangi,
Volume 6, Issue 2 (12-2020)
Abstract
The non-continuous laser beam in pulsed lasers allows the mechanical peening between two consecutive beams on a still hot weld bead. At a very short time (20, 150 and 300 ms) after laser pulse application, mechanical peening was performed on the welding bead. To achieve these short times, the light sensor detects the nth laser pulse and the mechanical arm starts moving. Upon reaching the tip of the pin near the workpiece, the n + 1th pulse was irradiated to the workpiece surface, and so the pin impact to the weld bead after traveling a short distance. Desirable mechanical properties were obtained at the highest time (300 ms) and highest pressure (6 bars). In this time and pressure the weld beads were not broken due to bending forces of peening.
M. Foumani, H. Naffakh-Moosavy, A. Rasouli, H. Aliyari,
Volume 8, Issue 1 (8-2022)
Abstract
Surface roughness in the welding processes is one of the important parameters in the laser welded metal connections which affects laser beam absorption directly. When the laser beam is irradiated to the surface of the base metal, the surface roughness plays an important role in the amount of beam absorption and the amount of melting achieved and directly affects the penetration depth. The main purpose of this study is to investigate the effect of roughness mentioned above in the equal parameter for this widely used aluminum alloy. Microstructural Surveys were performed on three different roughness levels of the sample and the results obtained from the analysis of samples by optical microscope (OM), atomic force microscope (AFM) and Scanning electron microscopy (SEM) analysis showed that, increasing the surface roughness up to Ra = 0.16 micrometer, caused the greater degree of beam engagement by the surface grooves, hence more concentration of the beam photons and more melting obtained, so the depth of penetration increases by consuming a lower amount of energy.
R. Mahdizade, S. A.asghar Akbari Mousavi, S. Mehdipour,
Volume 9, Issue 2 (1-2024)
Abstract
In this study, non-homogenous welding of nimonic 75 superalloy to Monel 400 with 1 mm thickness was investigated with pulsed Nd:YAG laser welding. The mechanical properties of the joint were analyzed with optical and scanning electron microscope, X-ray diffraction, micro-hardness test and tensile test. In the case of non-homogeneous welding of Nimoinc 75 superalloy to Monel 400, defects such as liquation cracks and porosity in the welded samples were observed. these defects were removed with increasing the preheating temperature and decreasing the heat input. The results showed the voltage, pulse width, pulse frequency and welding speed should be selected as 500 volts, 9 milliseconds, 3 Hz and 0.9 mm/s respectively to reach the proper penetration depth. Also, the investigations show that the welding structure is composed of austenitic matrix containing columnar dendrites and some cellular areas. The mechanical properties of the weld metal were reduced after joining and segregation causes a change in the amount of elements and the appearance of intermetallic compounds in the spaces between dendrites and cells. All non-homogeneous samples broke during the tensile test from the weld metal area.
