To perform TIG welding proper, a person must choose the correct type of filler rods. The quality of the weld depend on the type of filler rod that a person chooses. Choosing the wrong type of filler rod will cause problems during the welding process.
The type of metal being welded will determine the type of filler rod that a person need. For example, if the metal is thicker, then a person will need a thicker diameter of filler rod. For thin sheets of metal, thinner rods is used so as to not melt holes in the sheets of metal.
Choosing the right filler rod and gas for TIG welding
For thick metal, large diameter rods allow the welder to add metal quick to the weld area. However, large diameter rods will require the welder to have better control over the weld since cold laps can be an issue in these welds. If a person selects the wrong diameter of filler rod, the weld will be lacking in fusion, or the metal will be too thick for the type of metal being welded.
The alloy of the filler rod should match the alloy of the base metal. If the base metal is carbon steel, then the filler metal should be carbon steel as well. Triple deoxidized carbon steel rods will allow the metal to accept the mill scale that adheres to the metal.
High silicon carbon steel rods will work best for metals that are clean and do not have mill scale, as these metals create a flatter weld bead. For stainless steel, the filler metal will need to have a low amount of carbon content in order to allow the welded metal to remain free from corrosion. However, if the metal is exposed to salt water, then a person will need stainless steel with molybdenum to protect it from the corrosive properties of the salt water.
For aluminum metal, the filler metal rods will have a high percentage of silicon in order to prevent cracking in the weld metal castings. Alternatively, the metal may have a high percentage of magnesium to improve the strength of metal struts used in marine environment. For titanium metal, the rods will have to have a high degree of purity, as well as require that the welder back purge the metal to keep the oxygen metal away from the weld area.
Additionally, silicon bronze metal rods are used to weld metals that are of a different metal composition, such as weld galvanized steel to copper metal. Argon gas will be used for shielding the weld from air. Argon gas will be the most common shielding gas used in TIG welding processes.
However, for thick stainless steel metal, a person can add a percentage of helium to the argon gas to allow the weld to penetrate the thicker metal. Additionally, fifteen to twenty cubic foot of gas will be required per hour of welding operation. If the rate at which the shielding gas is provided is not within this range, turbulence in the metal will introduce air into the weld.
Gas lenses are often used to even out the shielding gas around the weld. These lenses will ensure even gas coverage for weld areas that are tight spots or for weld areas of titanium metal. Finally, the type of metal being welded will also determine the type of tungsten electrode.
Fine tungsten points are used for welding metals with low amperage, but thicker tungsten rods will be used for metal welding application with high amperage. The thickness of the metal to be welded will determine the size of the filler metal rods to use. Thin sheets will use small diameter metal rods.
For metal that is thicker than a half-inch, larger rods will be used in multi-pass welds. Filler metal rods should not be touched with bare hand. The oil on the human hand may create defect in the weld.
The filler rods should be wiped with acetone to keep them clean. Additionally, they should be stored in a way that makes it easy to find the correct type of metal rod. Metal rods of each type has specific color codes to them.
For example, blue can be used to indicate steel metal rods, green indicate stainless steel metal rods and yellow can be used to indicate aluminum metal rods. If the wrong alloy of metal rod is used, the weld will be weak and may crack in some area. Thus the alloy of the metal rods should match the alloy of the metal being welded.
