Multi-pass TIG welding was conducted on plates (15 × 300 × 180 mm³) of aluminum alloy Al-5083 that usually serves as the component material in structural applications such as cryogenics and chemical processing industries. Porosity formation and solidification cracking are the most common defects when TIG welding Al-5083 alloy, which is sensitive to the welding heat input. In the experiment, the heat input was varied from 0.89 kJ/mm to 5 kJ/mm designed by the combination of welding torch travel speed and welding current. Tensile, micro-Vicker hardness and Charpy impact tests were executed to witness the impetus response of heat input on the mechanical properties of the joints. Radiographic inspection was performed to assess the joint’s quality and welding defects. The results show that all the specimens displayed inferior mechanical properties as compared to the base alloy. It was established that porosity was progressively abridged by the increase of heat input. The results also clinched that the use of medium heat input (1–2 kJ/mm) offered the best mechanical properties by eradicating welding defects, in which only about 18.26% of strength was lost. The yield strength of all the welded specimens remained unaffected indicated no influence of heat input. Partially melted zone (PMZ) width also affected by heat input, which became widened with the increase of heat input. The grain size of PMZ was found to be coarser than the respective grain size in the fusion zone. Charpy impact testing revealed that the absorbed energy by low heat input specimen (welded at high speed) was greater than that of high heat input (welded at low speed) because of low porosity and the formation of equiaxed grains which induce better impact toughness. Cryogenic (−196 °C) impact testing was also performed and the results corroborate that impact properties under the cryogenic environment revealed no appreciable change after welding at designated heat input. Finally, Macro and micro fractured surfaces of tensile and impact specimens were analyzed using Stereo and Scanning Electron Microscopy (SEM), which have supported the experimental findings.

在板材 (15 × 300 × 180 mm ³) 铝合金 Al-5083，通常在低温和化学加工工业等结构应用中用作组件材料。气孔形成和凝固裂纹是TIG焊接Al-5083合金时最常见的缺陷，对焊接热输入很敏感。在实验中，热输入从 0.89 kJ/mm 变化到 5 kJ/mm，由焊枪行进速度和焊接电流组合设计。执行拉伸、显微维氏硬度和夏比冲击试验，以见证热量输入对接头机械性能的推动响应。进行射线照相检查以评估接头的质量和焊接缺陷。结果表明，与基体合金相比，所有试样都显示出较差的机械性能。已确定孔隙率随着热输入的增加而逐渐减少。结果还表明，通过消除焊接缺陷，中等热输入 (1-2 kJ/mm) 的使用提供了最佳的机械性能，其中仅损失了约 18.26% 的强度。所有焊接试样的屈服强度保持不受影响，表明没有热输入的影响。部分熔化区（PMZ）宽度也受热输入的影响，随着热输入的增加而变宽。发现 PMZ 的晶粒尺寸比熔合区中的相应晶粒尺寸更粗。夏比冲击试验表明，低热输入试样（高速焊接）的吸收能量大于高热输入试样（低速焊接），因为低孔隙率和等轴晶粒的形成导致更好的冲击韧性。还进行了低温 (-196 °C) 冲击测试，结果证实低温环境下的冲击性能显示在指定的热输入焊接后没有明显变化。最后，使用立体和扫描电子显微镜 (SEM) 分析拉伸和冲击试样的宏观和微观断裂表面，这支持了实验结果。还进行了低温 (-196 °C) 冲击测试，结果证实低温环境下的冲击性能显示在指定的热输入焊接后没有明显变化。最后，使用立体和扫描电子显微镜 (SEM) 分析拉伸和冲击试样的宏观和微观断裂表面，这支持了实验结果。还进行了低温 (-196 °C) 冲击测试，结果证实低温环境下的冲击性能显示在指定的热输入焊接后没有明显变化。最后，使用立体和扫描电子显微镜 (SEM) 分析拉伸和冲击试样的宏观和微观断裂表面，这支持了实验结果。