PSI - Issue 33

Rizki Dwi Ardika et al. / Procedia Structural Integrity 33 (2021) 171–180 Author name / Structural Integrity Pro edi 00 (2019) 000– 00

177

Wu et al . (2015)

Aluminum alloy 7075-T6

laser-MIG hybrid welding

Effect of interaction between pores and fatigue damage at the 7075-T6 junction Microstructure and porosity distribution in 5A06 aluminum alloy welded joints

Gas porosity in welding causes fatigue cracking. The increased pore count causes a fatigue cycle to occur in the weld joint In the welded joints, metallurgical pores were found caused by dissolved gas and Mg evaporation. The pore size ranges from 29 µm to 52 µm. Pore formation affects the softening of the weld joint. evaporation of Mg cause the welding process to be unstable and lower actual heat input. The 6061/5182 joint has more crack sensitivity and has a significant influence on tensile strength. Porosity and pore morphology appear due to the content of the element Mg. Microhardness decreases with increasing Mg element content.

4

Zhan et al. (2018) Aluminum alloy 5A06

laser-MIG hybrid welding

5

Chen et al . (2020) Aluminum alloy 5182 dan 6061

laser welding

Mechanical properties, microstructure, and porosity in laser welding of 5182 and 6061 aluminum alloys

6

8. Reduce porosity defects Hydrogen solubility decreases with decreasing temperature and results in reduced porosity. In a study conducted by Zhan et al. (2020) using a hybrid MIG laser welding process with speed parameters of 2 m/min and 3 m/min, at low speed (2 m/min) in the molten pool area, there is a lot of dissolved hydrogen and has the potential to form porosity in the weld joint and on the other hand, welding at a speed of 3 m/min has very little hydrogen solubility. The suitable welding speed is an important parameter that affects the reduction of dissolved hydrogen in the weld pool area, thereby reducing the weld joint's porosity (Zhan et al., 2018). High arc currents cause the interaction effect of laser arc and melt flow so that bubbles come out of the molten pool and reduce porosity (C. Zhang et al., 2016). In welding using CMT, CMT pulse advanced (CMT-PADV) is a suitable welding process. because can precipitate aluminum alloys and control porosity. Several factors that can control porosity are low heat input, fine grain structure, and effective removal of oxides from the wire (Cong et al., 2015). A suitable torch position, optimal welding conditions, and a suitable welding range can also control porosity in CMT welding (J. Yu & Kim, 2018). Liu et al. (2015) Performed fillet weld on aluminum alloys using pulsed gas metal arc welding with CO2 and He to the shielding gas. He has a high ionization potential, causing heat to enter the base metal and produce melt in the molten pool for a long time so that bubbles can get out of the molten pool more easily. CO2 gas oxidizes to have CO and O at high temperatures, and oxygen reacts with hydrogen in the arc column atmosphere, reducing the hydrogen content in the molten pool. Also, CO2 gas can speed up the droplet transfer frequency, resulting in a reduced absorption time of droplet-melted hydrogen. The addition of CO2 and He in the shielding gas and the suitable torch angle can reduce the porosity (Liu et al., 2015). The precise control of the shielding gas parameters, including the different flow rates, the blowing angle, and the shielding gas distance, is also a determining factor during the welding process in reducing porosity (K. Li et al., 2015). The effect of welding parameters such as arc pressure and the environment is very influential in reducing porosity. Appropriate arc pressure parameters can reduce the porosity in welding (Katayama et al., 2006). The right environmental parameters can minimize the porosity. The wind speed and humidity that are suitable during the welding process can significantly reduce the porosity of the weld joint (Chinakhov et al., 2015).