Yes, it is possible to TIG weld steel with an AC machine. It has been observed that people generally do not prefer to weld steel using AC, but this does not necessarily mean that AC cannot be used for steel welding. For steel welding, it is recommended that DC is used.
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A beginner to TIG welding may have trouble choosing between AC and DC to weld steel. It is quite common to see people welding steel with DC power and aluminum with AC power.
If you are using only AC power to TIG weld steel, you might be wondering if it is possible to TIG weld steel with AC power.
I want to ask another question. When you can use AC power for welding steel, why do people prefer to use DC power? As it turns out, DC power offers some benefits, particularly when welding steel.
There are some disadvantages if you use AC, so you must consider them before using it. Let’s have a look at any of those issues in more detail so that you can make the most informed decision possible regarding TIG welding steel.
Should I Use AC Or DC For Welding Steel?
You can use both AC and DC power sources to TIG weld steel. Generally speaking, AC power is not recommended for welding steel.
Consider buying a machine for welding steel that DC can operate if you purchase a new one for welding. Welding steel with AC is not the most efficient way to do it.
The use of AC is more common for aluminum than steel. This is because aluminum often has a film protector that needs to be removed before welding occurs.
The presence of DC is sufficient for welding steel since steel doesn’t have such a thing. Before welding, steel should be prepared by hand, preferably using either a metal brush or a grinder.
As a result of the unstable arc produced while welding steel using AC, there is a bad penetration of the steel when welding steel using AC. As a consequence, the tip of the welding rod might melt.
While it might seem that mild welding steel with an AC machine is not the best option for our applications, we can do it so long as we are comfortable with it.
It is important to remember that quality is the most important aspect, and regardless of what method you use for welding, it must be guaranteed.
The Process of TIG Welding Steel Using AC
If you’re forced to use AC due to the weather conditions, you will have to keep a few things in mind. AC is not designed for working on steel, so you must adhere to some precautions as AC is not recommended for working on steel.
In the following steps, you will be guided through the process of welding steel using AC easily and with almost no downsides.
In the first place, carbon dioxide can’t be used if you’re using AC for welding steel.
Unless you use argon, you’re not going to be able to use it. To use an AC cylinder in conjunction with argon, you will need a large cylinder. It would be best if you had enough argon in stock before you start welding, as argon cylinders deplete much faster than you might think.
It is possible to set your flow rate between 15 and 20 CFH and keep it at that level. It is unnecessary to waste more argon since it is already going into consumption at a higher rate than carbon dioxide.
Please remember that the frequency box is the key to making sure you have enough argon. It is not recommended to use TIG alone because the arc is too unstable. With a frequency box, the arc will be stabilized by using the high frequencies it provides.
Suppose you are using AC; the direction of the flow of current changes at a speed of 60 Hz. This scenario results in the arc igniting in the positive cycle, then extinguishing, and then reigniting in the negative cycle.
During this cycle, there is a gap between the electrode and the base metal during the process of conducting this cycle.
It’s here that high frequency is required because that’s where it’s needed. By bridging this gap in the transition between positive and negative cycles, high frequency creates an access point between the two and facilitates the welding process in its entirety. The next part of this article will describe this high-frequency model with more information.
The Difference Between AC and DC in Terms of Welding
This article will cover the differences between AC and DC welding, so you don’t have to worry about it. I will explain the differences between AC and DC welding in the following sections.
In the first place, DC, or direct current, is called so because it makes sure that the current flows only in one direction.
Unlike an AC TIG welder, the current flow does not stop after welding. The majority of TIG inverters on the market today can switch between AC and DC, except for a few cheap machines.
It turns out that the direct current – electrode negative (DCEN) method can be used to treat a variety of materials.
Alternatively, the welding torch can be connected to the negative output of the welding inverter when using the DC power source. This cable is then plugged back into the TIG welder’s positive output to return the positive current.
Direct current electrode positive (DCEP) is the polar opposite of electrode negative direct current (DC). In this case, the welding torch receives the positive output and returns the negative output. I wonder how DC can assist us in our day-to-day work?
If the surface of some non-ferrous materials is kept open in the normal atmosphere, like aluminum, an oxide may form on the surface.
Oxygen, which is present in the air, reacts with the surface of the metal, forming the oxide. This oxide must be removed from the base material before welding because it has a lower melting point than the base material.
It is possible to easily remove this oxide by grinding, brushing, or using some chemicals. Nevertheless, it is more efficient if it is removed during welding, as it forms when you keep the object in the air while welding.
Direct current is very helpful when it comes to this type of problem. As a result of the electron flow from DC, the oxide layer over the aluminum is broken down and removed.
Using DCEN in conjunction with DCEP, deep penetration is achieved while also breaking down the oxide, resulting in a high-quality weld.
The problem with this combination is that it is incredibly difficult to achieve. One of the major challenges is the high temperature of DCEP, which makes it difficult for penetration to occur. I suggest that you use only AC rather than both DCEP and DCEN.
With the alternating current mode (or AC mode for short), you can present both the positive current and the negative current at the same time.
When the welding inverter is operated in this mode, either positive and negative elements are supplied or alternate half-cycles. The AC system has one positive and one negative element combined into one complete cycle called one cycle.
An alternating current is defined as a current that alternates from one direction to another at different times, which is why it is named alternating current.
It should be noted that the AC mode operates at an extremely high frequency of 50-60 Hertz, which increases the magnetic effects.
This increased magnetic effect is a major factor in transformer efficiency and stability. As a result, you can control the process of welding much more effectively.
Welders who are regular users of welding machines will find AC is a more efficient way of welding. AC provides maximum penetration using increased heat while maintaining a stable travel speed.
To accomplish this goal, you must adjust the control so that it is in a position that will extend the time spent in the negative half cycle. By doing this, you can employ higher currents with smaller electrodes while the heat will go to the positive cycle, which will result in deeper penetration.
It is also possible for AC to help you with cleaning if you need that. The best way to achieve that is to do completely the opposite of what you did for maximum penetration.
If you want to maximize the time spent on positive cycles, you must position your control so that it maximizes this time. Only then can you obtain decent penetration and active cleaning currents.
In the end, I hope that you will have been able to decide based on the information provided about what currency you will need to use for TIG welding steel and whether or not AC can also be used for TIG welding steel after reading this article.
It is not debatable that it is possible. However, if it were true, there would be a lot of unnecessary complications, and some individuals may not justify the existence of such a program. Once again, thank you for reading, and I wish you the best of luck with your project. Until the next time, take care.
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Hi, I’m Andrew Miller — a certified welding expert and instructor based in Long Island, NY.
With over three decades in the industry, I’m passionate about combining theoretical knowledge with hands-on experience to train the next generation of skilled welders.
I specialize in all forms of arc welding, including GMAW, GTAW, GMAW, FCAW & SAW. But my experience isn’t limited to just those—I’m also knowledgeable in oxyfuel gas welding and plasma arc cutting.
My years as a welding inspector and supervisor have honed my ability to ensure the highest standards in welding quality and safety, making me adept at executing and overseeing complex welding operations.
You can find more information about me on my website, weldingzilla.com, or connect with me on LinkedIn.