Investing in inverter power, pulse technology, or even a mixture of argon and hydrogen shielding gas can provide short- and long-term benefits for TIG welders and shop owners who work with stainless steel. Getty Images
Welding stainless steel using gas tungsten arc welding (GTAW), also known as TIG, can often be challenging.
You don’t want to heat stainless steel too much because stainless steel tends to be a more sensitive material. Therefore, heat input and heating calculations are very important.
This is where welding travel speed comes into play. When TIG welding stainless steel, the faster you move, the less time you spend welding the part, which means less heat is absorbed by the surrounding material.
Investing in a small portable inverter power supply, switching mode power supply, or even a hybrid argon-hydrogen shielding gas can benefit both TIG welders and shop owners by helping to optimize heat input, travel speed, and weld penetration.
For many people, working with stainless steel means working with pipes and pipes in workplaces such as poultry processing plants, vodka distilleries, microbreweries, pharmaceutical plants, and more.
Much of the work can now be done in-house, often using larger welding equipment. But ultimately, in most cases, you will have to travel to job sites where large transformer machines are inconvenient due to power input requirements and transportation logistics.
“First of all, they’re very heavy,” said Andrew Pfaller, Miller’s electrical division manager. “But if you find the strength, do you have the right connections? Do you need to link a product? This often creates problems.”
Portable inverter power supplies typically weigh less than 50 pounds, making them significantly smaller than transformer machines. “It’s about the size of a lunchbox,” Pfaller said. Most are rated at 150, 160, or 200 amps, since field work can often be done at 200 amps or less.
“You can usually move an inverter machine to a job site yourself, without having to use a forklift or have someone help you lift it… if you can do it with one person instead of two. This task will have a significant impact on your productivity and profitability,” he said.
In addition to portability, inverter technology allows pulses to be generated at higher frequencies. Transformer power supplies typically produce 10 to 20 pulses per second. Inverter power supplies can reach 500 pulses per second; some can even reach 5000 pulses per second;
In addition to portability, inverter power also allows for higher frequency pulsing, which ultimately provides better directional control and reduced arc lag. Miller Electric
“Whether you’re trying to make fillet welds, internal fillet joints or TKY joints in pipes and tubes, this allows you to direct the arc and weld point where you want it,” he said.
“Plumbing pipes and tubes, widely used in the food, beverage and dairy industries, are made of thin-walled stainless steel with relatively low current; The arc force created by the current is not that great. You want the arc created by the impulse. stability to complement that.”
Using a pulse generator helps reduce “arc lag,” which is when the welding arc lags behind where the electrode is pointed and where the weld puddle actually forms.
“This is probably a bad way to describe it, but it’s almost like being drunk. Your brain is thinking one thing, but your body’s response is lagging,” Pfaller said. “The material in these nickel alloys behaves the same: it reacts slowly to stress.
“Using a pulse generator causes the bath to agitate, which reduces lag and lag in the bath. So what does this mean for someone? This can mean improved welding quality because the welding is now done the way they want.” no need to wait for the puddle to catch up.”
The pulse mode reduces the heat supply to the weld, thereby reducing the degree of deformation. Pfaller said that typically, steel shrinks about 10% as it hardens.
“If you have a weld joint and you create a weld pool that is much larger than necessary, it will shrink, and when it hardens, it can cause excessive distortion,” he said. “This distortion often leads to some form of revision or editing process, but this is not taken into account. Companies spend a lot of time repairing or straightening objects after welding and before subsequent operations.”
Historically, TIG welders used argon as a shielding gas when welding stainless steel. However, in some applications, such as welding thin-walled pipes, some have switched to using low percentage hydrogen mixtures. In this case, approximately 1% to 2% hydrogen is mixed with argon.
Pfaller said he is seeing an increase in the use of argon and hydrogen hybrid shielding gases. This mixture generates more heat, which leads to a change in the weld penetration profile.
“People who make sanitary pipes or thin-wall pipes will use square butt joints instead of chamfering the pipe. They then use a shielding gas mixed with hydrogen and do additional fusion to virtually eliminate joint preparation,” he said.
Unlike helium, which is currently experiencing a supply shortage, its supply is not an issue given the relative abundance of hydrogen and argon in the atmosphere.
Pfaller said some companies choose to mix it themselves. He warned stores to be careful because the mixture is highly flammable at higher concentrations.
“Those conducting their own mixing research must take the necessary precautions to ensure that the proportions in the shielding gas mixture are kept very low,” he said. “If you mix it yourself rather than bringing in a pre-mixed mixture from your gas supplier, it can create safety issues and precautions need to be taken. Their shielding gas supplier can provide some advice and guidance in this regard.”
Ultimately, Pfaller says, making changes in these areas will provide more financial benefit than trying to save budget on supplies or replacing TIG torch cups.
Many of those Pfaller spoke with haven’t made changes because welding makes up about 10 percent of their shop’s business. If the welding speed is increased by 10%, the overall operation volume can be saved by approximately 1%.
The benefits of switching to inverter power and pulse mode include eliminating unnecessary work, using more aggressive joint profiles, eliminating pipe bevels, and fully welding square butt joints.
“The majority of a company’s time is spent on pre-weld preparation and post-weld rework and operations,” Pfaller said.
“Thanks to technologies such as DC pulses, you can now reduce or virtually eliminate some of the other welding tasks. If you can eliminate them, now you’re not just eliminating 1%, you’re eliminating 10%, 20% of transactions. % of the company, 30% pre- and post-weld operations,” he said.
Rafael Guerrero. Appointed editor of Welder magazine in April 2022. He spent nine years as a reporter for newspapers in the Midwest and Pacific Northwest, covering issues and communities in central Illinois, Washington, D.C. and the Chicago area.
Formerly known as Practical Welding Today, Welder showcases the real people who make the products we use and work with every day. The magazine has served the North American welding community well for over 20 years.
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Post time: Jul-05-2024