How to Troubleshoot and Rectify Tig Weld Inconsistencies
How to Troubleshoot and Rectify TIG Weld Inconsistencies
TIG welding is a challenging task even for welders with years of experience and most definitely for someone who is new to the task or a rookie. Discontinuities in the weld are common issues associated with TIG welding and can compromise the strength of a weld.
There are many forms of inconsistencies that may develop in a TIG weld; one example of discontinuity is known as porosity. Porosity signifies gas pockets that form into the welded metal. Normally porosity can be easily detected with the naked eye in the form of small holes. However, testing devices like X-Rays are used in the case of critical welds.
There are many reasons as to why porosity occurs during TIG welding. Improper filler metal, wrong type of coverage for shielding gas, more than specified heat or a base metal which was not cleaned are all potential causes for porosity.
To rectify the issue, make sure that you inspect the hoses, in case there are any cracks responsible for gas leaks. In addition, check and double check that torch fittings are properly tightened. One trick to finding loose or improper connections is covering the hose and all the fittings with soapy water, this will help you locate the leak and then you can tighten them accordingly. Of course, if necessary, you should replace any hoses that are damaged.
Always use a precise range of 10 to 20 CFH (Cubic feet per hour) for the flow rate of shielding gas, this will ensure that you get proper coverage. If you set the rate any higher than this, you will face problems like puddle turbulence in welds, however, lower rates would not be able to protect weld puddles against the atmosphere. In other words, a range higher or lower than 10 to 20 CFH may lead to porosity.
Choosing the correct filler rod and the right shielding gas is another very effective way to prevent porosity. Being specific, you should select a proper designation filler rod for the base material you plan to weld. If you have doubts, contact the manufacturer for the filler metal or contact a distributor to make sure of the best option. Off the bat, never use CO2, always use Argon as a shielding gas.
Another reason for porosity is applying too much heat on the material. Limit the amperage range to 80 to 120 for material with thickness between 1/8 and 3/16-inch. Be very cautious with the amperage when working with carbon steel as porosity is caused if excessive heat is used.
Lastly, always check and then double check your base metal for any signs of grease, moisture, oil or dirt. Be sure to clean the base metal properly. When working with aluminum, be sure to clean it before you start to weld, because if you don’t, there is a high chance of porosity.
Frequent issues with TIG welding also include scarcity of fusion or undercutting.
Undercutting is a term given to a grove that forms alongside the edges of a weld, and is not properly filled with the weld metal. The main reason for this is a torch angle which is improper; the torch angle is the result of inconsistent heat distribution on the joint being welded. For instance, if a T-joint is being welded and there is 60% heat directed at the top of the piece and a mere 40% at the bottom one, it is very likely for undercutting to occur. Not only that, the join will also be weak.
Simple steps can be taken to rectify undercutting. Undercutting can be fixed by initiating an arc Once done, simply set up a weld puddle and check for an equal spread of the weld puddle at both ends of the joint. Make adjustments to the torch angle to ensure proper heat distribution. Lastly, see to it that the filler flows into the weld puddle with an even flow. This will also give you an indication that the distribution of heat is similar on both ends of the joint.
Lack of fusion
When TIG welding is being done in multiple passes, incomplete fusion can occur. This particular inconsistency is also known as lack of fusion. This is the result of a weld that does not fuse to the next weld beat or to a base material. This also weakens the joint.
If the regular amperage is reduced significantly on a thick material, it can result in lack of fusion or incomplete fusion. A rule of thumb for a situation as such would be to use one ampere per every 0.001 inch of the material’s thickness that you’re TIG welding.
Another cause for lack of fusion is improper joint preparation. There are 2 ways this can be remedied. Firstly, you may make space between the joints or bevel the joint pieces. For instance, if welding pieces of quarter-inch material, create space between the material pieces. The space between the pieces should approximately be 1/8 inch, once done; you can fill the space using weld metal.
The addition of helium to the argon shielding gas will result in a weld puddle that is hotter; this will increase the penetration of the weld and reduce the probability of incomplete fusion. This is a good tip if you are welding a half-inch think aluminum.
Excessive penetration is another very common inconsistency that can occur in welds. This happens if the weld metal falls through the welding joint. This is usually the result of slow travel speed of excess heat. If you weld a joint slower than you should, there is an excessive buildup of heat on the base metal, eventually causing the metal to penetrate right through the joint.
Maintaining a travel speed that’s able to form a weld puddle about two times the diameter of the wolfram is a very effective way to avoid excessive penetration. Surely this will take a fair amount of practice but you can use the following ticker to help you determine whether you are going at the right pace or not. If the weld puddle is high, crowned and narrower than the wolfram that you are using, you are going too fast or the heat is low. On the other hand, if the weld puddle is about 3 times the size of the wolfram, you are welding slowly. In either case, you need to adjust your welding speed immediately.
Excessive penetration usually occurs because the amperage has been set too high. Remember the rules of amperage at all times, one ampere per every 0.001 inch of the material’s thickness.
Practice makes perfect, remember this as enough practice will make sure that you avoid these welding inconsistencies at all times. But then again, we’re only human and we all make mistakes. At the end of the day, it is the knowledge of how to correct your mistakes that counts.
Refer to the Longevity website (www. Longevity.inc.com) or check out the YouTube Channel (www.youtube.com/longevitywelding) for more information and details about the different equipments used for the many welding and cutting procedures. Longevity has all the right machines for your exact application, so do check out and choose what best fits for your product, materials, and requirements.