Welding Science 101

 

The Art of welding is a valuable skill to learn and master. Just like with anything else the more you learn and the more you practice the more successful you will be. The technology in welding continues to get more advanced. But in this industry it is beneficial to learn both traditional welding methods as well as the newer advanced welding methods. It will make you a more versatile welder and will broaden your horizons for more opportunities.

When it comes to becoming an excellent welder, it’s more than just running a perfect bead. It’s understanding the science of welding. For example, you need to know why you have different gas mixtures for the type of welding processes or the right currents for what type of metal you are working with. There is much to learn about each type of welding process and many large books have been written on the subject. In this article, we are going to cover the basics of the four standard welding processes.

Basic Terms To Understand

 

Electrode:  A conductor for the electrical current during the welding process.

Flux: A coating used to cover the electrode. When the flux starts to burn off the electrode it turns into a gas to protect the weld from oxidation.

Arc:  Is a plasma between two electrodes create by electricity. This happens when a circuit is broken but the two electrodes still are close to one another.

Weld Penetration: The depth of the weld that joins two pieces of metal together.

Welding Slag: Is a coating that forms over the weld from the remaining flux after the joined metal starts to cool.

Welding Processes

Shielded Metal Arc Welding (SMAW) or “Stick” is a welding process that has been used since the early 1900’s. This welding process is widely known and used because of its low cost, portability, and versatility.  With an average arc temperature of 11,000 degrees Fahrenheit this process causes the flux around the electrode to vaporize into a gas. The gas then covers the weld pool to protect the weld from oxidation. Flux is made of different types of compounds like cellulose which helps with deep weld penetration. Another compound found in the flux is calcium fluoride which helps with the stability of the arc. After the electrode passes by, the flux creates a slag over the weld. Even though the slag is from the gases that were for protecting the weld during the SMAW process,  the hardened slag helps with the cooling rate of the weld.

The SMAW process uses three different types of currents depending on the electrode and the base metal you are welding. The three currents are Direct-Current Electrode Negative, Direct-Current Electrode Positive, and Alternating Current. The most common used is Direct-Current Electrode Positive because it allows you to run a better weld bead and achieve deeper penetration.

Pros List:

  • Quick set-up
  • Works well outside
  • Works well in windy conditions
  • Low cost

Cons List:

  • Generally harder to control the weld puddle
  • Slow welding process
  • Not the best for welding thin metal – risk of burning through

Epic Blue Fab type of metal experience with shielded metal arc welding

  • Steel

Gas Metal Arc Welding (GMAW) or “MIG” is a welding process that uses a solid metal wire on a spool. The wire is then fed from the welder and travels through the wire liner then into the welding gun. From there it will make a complete circuit when it comes into contact with the metal being welded. As the wire is being fed through the wire liner there is gas being fed through the shielding gas hose. The gas that is used for GMAW process is performing the same function as in the SMAW welding process – it is coating the weld to protect from oxidation.

GMAW can be automatic or semiautomatic which means you can complete your welding projects at a faster rate the SMAW. For most people learning the basics of GMAW can be done in just a few hours. The most common gases used for this type of welding are carbon dioxide, argon, and helium. It is important to know what gas to use for your project as well as what to set your gas flow rate too. When welding with gas it is better to work indoors especially if it is windy. You can weld outdoors with a gas welding process but you will need to set up a wind block to stop even the slightest breeze. When the gas gets blown away the weld can get “worm track” or “porosity” which looks horrible.

Pros List:

  • Quick welding process
  • Cleaner welding process
  • Easy weld pool control
  • Easy to learn
  • Quick clean up

Cons List:

  • Difficult in windy conditions
  • More expensive than Stick welding
  • More equipment to move around the job site

Epic Blue Fab type of metal experience with gas metal arc welding

  • Steel
  • Aluminum 

Flux Core Arc Welding (FCAW) is similar to GMAW and is known for portability and the good penetration of the weld. One reason why  FCAW is popular to use is that (as the name suggests) the wire has flux inside the electrode that creates protection over the weld that makes welding outside effective. This process can also be semi-automatic or automatic which allows for increased speed while still maintaining quality welds. Other FCAW wire does need to have an extra supply of shielding gas to help protect the weld this is called Dual Shield.

Pros List:

  • Works well outside
  • Works well in windy conditions
  • Flux in core so no extra gas needed

Cons List:

  • Harder to control the weld puddle
  • More weld splatter, means longer cleanup time
  • During the welding process there is more smoke – reduces visibility
  • Flux wire is more expensive

Epic Blue Fab type of metal experience with flux core arc welding

  • Steel
  • Aluminum 

Gas Tungsten Arc Welding (GTAW) or “TIG” welding is a process that uses gas to help with protecting the weld bead from oxidation.  The TIG welding process is a lot different than SMAW or GMAW because in TIG welding you use different equipment. TIG welders have a torch handle with a tungsten rod inside and a cup that is attached to the front that assists with gas flow. When it comes to controlling the heat you use a finger control or a pedal control that improves control of the weld. This process helps with creating high quality, coin stacked welds.

TIG welding is a little harder to master than other welding process.  When it comes to mastering TIG there are many things to learn like knowing how to control the heat, the puddle, and feeding the filler metal at the same time. On top of this one needs to understand the right currents to use along with the right tungsten to use with the right base metal. The most common metals you can TIG weld are aluminum, carbon steel, steel, and stainless steel. The most common gases used for TIG welding are argon and helium.  After you master the art of GTAW you can weld a variety of metals with a high-quality weld.

This article was just an introduction to welding meant to just cover the basics of the four common welding processes. Epic Blue Fabrication is working hard to provide articles detailing everything about the welding industry. For more about Epic Blue Fabrication go to epicbluefab.com

Pros List:

  • High-quality welds
  • Good weld penetration
  • Great welding process for thin metal
  • Clean welding process

Cons List:

  • Slower welding process
  • Difficult in windy conditions
  • More expensive equipment

Epic Blue Fab type of metal experience with gas tungsten arc welding

  • Steel
  • Aluminum
  • Stainless steel