Welding galvanized steel involves joining pieces of steel coated with a special zinc layer. The zinc coating helps to prevent the steel from rusting, but it is more difficult to weld than regular steel. You need to be extra careful when welding this type of steel because zinc produces dangerous fumes that can make the weld weak if not done properly.
What is galvanized steel?
Galvanized steel is ordinary steel that is coated with a layer of zinc to protect it. This special coating acts as a protective shield that prevents the steel from rusting when it is exposed to the elements outdoors. Many companies use galvanized steel because it can be used for long periods of time without damage. The zinc coating makes welding more difficult compared to regular steel, so welders need to learn special welding methods.
Problems with welding galvanized steel
The zinc coating can cause some tricky problems when welding. When a welder heats up the steel, the zinc turns into a gas before the steel gets hot enough to melt. This can result in a poor weld and create unpleasant fumes that are not good for breathing. Zinc and steel react differently to heat, making welding galvanized steel much more difficult than regular steel.
Different methods for welding galvanized steel
There are three main methods that welders can use to weld galvanized steel together. These methods are arc welding, shielded gas welding (also known as MAG), and laser welding. Each method has advantages and disadvantages.
Arc Welding
Arc welding is an older method that many welders still use today. There are several problems with this method that make it cumbersome to use. Arc welding takes longer to complete the job compared to other methods. The heat from arc welding spreads too quickly and can warp nearby steel. When using arc welding, it often burns off the protective layer of zinc around the weld. This method also causes a lot of small metal debris to spray everywhere, which means more cleanup later.
Shielded Gas Welding (MAG)
MAG welding works differently from arc welding and has its own advantages and disadvantages. This method allows the welder to work faster, which is helpful when a lot of welding needs to be done. The strong current can bend and distort the metal at the weld. Sometimes the wire penetrates deep into the metal and burns through the zinc. Even though MAG welding is faster, it still generates too much heat, which can burn off the zinc that protects the steel from rusting.
Laser Welding
Laser welding is a relatively new method of welding metals. Instead of using electricity or gases like older methods, it uses a powerful beam of focused light to heat and melt the metals to be joined. The laser beam concentrates all the energy in a very small spot, resulting in a very clean and precise weld. Since the heat stays in a very small area, it does not damage the metal around the weld.
Laser welding gets the job done faster than other methods. The focus of the laser is very tight, which means that the metal will not bend or warp due to too much heat spreading around it. Laser welding uses less electricity than older welding methods, which saves money on your electric bill. Best of all, laser welding doesn’t burn off much of the zinc layer that protects the steel from rusting.
Why choose laser welding?
Laser welding is very effective on galvanized steel for a number of reasons. The process keeps the metal flat and straight because there is no excessive heat generated. The welder can control the laser beam very carefully, which helps protect the zinc coating and prevents the steel from rusting. Since nothing but the laser beam touches the metal, the weld comes out clean and precise. Laser welding does not waste as much energy as older methods such as arc welding. The focused laser beam helps keep most of the zinc coating intact, which protects the steel from rusting.
Using a Handheld Laser Welder
Many welders use handheld laser welding machines to weld galvanized steel. These machines work well for welding thin metal sheets, but they can also weld thicker metal sheets if set up properly. Handheld laser welders typically work best on galvanized steel between 1 and 3 mm thick. For 1 mm thick metal, the laser only needs 600 watts of power to work well. Thicker metals require more power, about 1,200 watts for 2 mm thick steel. Some of the more powerful laser welding machines can even weld steel up to 7 mm thick at a time.
Best Practices for Welding Galvanized Steel
When working with galvanized steel, there are some important steps you need to follow to get a good weld. These straightforward guidelines will help keep you safe and ensure that your welds are strong, clean, and built to last for a long time.
First, heat the metal before you begin welding. Getting the right temperature beforehand will help prevent the metal from cracking and make for a better weld.
Your work area must have good air circulation. Working with galvanized steel creates dangerous zinc-containing fumes that can be very unpleasant to inhale.
Make sure the metal is clean before you start working. Any dirt, oil or other filth on the surface can cause problems and make the weld vulnerable.
Choose the right welding method for your project. Laser welding is best suited for most galvanized steel projects because it is very precise and doesn’t cause too much damage to the protective layer of zinc.
Change the power setting according to the thickness of the metal. Different thicknesses of metal require different amounts of power to weld properly.
Conclusion
Welding galvanized steel requires extra care because it has a zinc coating. The zinc coating helps protect the steel from rusting, but it also makes welding more difficult than with regular steel. Most basic welding methods burn off the zinc coating, making for a weak weld. However, laser welding offers a better solution that retains more of the protective layer. Handheld laser welding machines can easily weld galvanized steel up to 3 mm thick. The latest laser welding machines can even weld steel up to 7 mm thick. If you follow these steps and use the right tools, you will be able to produce a strong, clean weld on galvanized steel. Your welds will look great and remain strong for many years to come.
