| What kind of Structures are made from | | | | great deal of its strength when welded and the |
| aluminum? The first thing that comes to mind is | | | | procedure used to weld it can greatly affect the |
| Ships. Aluminum hull ships are becoming | | | | outcome. Usually, its a struggle to use enough |
| increasingly in demand for military applications as | | | | heat input to limit porosity, while at the same |
| well as for commercial transportation. | | | | time, use low enough heat input not to alter the |
| Why? Aluminum is lighter and that saves fuel and | | | | strength and other physical properties of the alloy. |
| increases speed. | | | | Carbon steel will harden if it is heated to a high |
| AWS D1.2 is the Structural welding code for | | | | enough temperature and then cooled quickly. |
| aluminum. It not only provides weld joint design | | | | That's how we make knife blades and such. |
| and limitations but also specifies how welders are | | | | But aluminum is just the opposite. When it is |
| to be certified for welding aluminum. | | | | heated to an elevated temperature as happens |
| The main processes used to weld aluminum | | | | during welding, it immediately begins to lose its |
| structures are Gas Tungsten Arc (GTAW) , Gas | | | | hardness, whether its a heat treatable alloy like |
| Metal Arc (GMAW), and variable polarity plasma | | | | 6061 t6, or 3003 h14. Either way it loses hardness |
| arc (VPPAW). Gas metal arc is the mainstay | | | | and strength if it gets hot enough. Quick |
| welding process for shipbuilding but friction stir is | | | | quenching after heating only ensures softness. |
| being researched as a possibility in the future. | | | | AWS D1.2 requires the use of qualified welding |
| Along with the need to certify the welder, It is | | | | procedures to ensure minimal tensile properties |
| especially important for the procedure to be | | | | are met in the weld metal as well as the heat |
| qualified for aluminum structures. Aluminum loses a | | | | affected zone. |