Welding For Dummies. Steven Robert Farnsworth

to use on your power tool is the same as the metal you’re going to weld. For example, if you’re going to be cleaning a piece of steel, make sure you use a steel wire brush or grinder, not one made of brass or another metal. Otherwise, you run the risk of contaminating the metal with another metal. The exception? It’s okay to use a stainless steel wire brush on aluminum.

Tools powered by electricity or pressurized air have become the standard for cleaning steel in many welding shops, especially for shops that weld large pieces. The most common power tools used for cleaning steel are angle grinders, shown in Figure 2-2. An angle grinder in use is depicted in Figure 2-3.

      FIGURE 2-2: A typical angle grinder.

      

You may think that you can ease up a little on your safety precautions when you’re cleaning a piece of metal but not yet welding it, but don’t be fooled. You can be injured during the cleaning process, particularly if you’re using power tools to clean the metal. Head to Chapter 3 for the lowdown on safety.

      Cleaning steel with chemicals

      Chemical cleaning is, as you can probably guess, a way to clean steel by using harsh chemicals. I’m talking about some pretty rough chemicals here, so if you go the chemical cleaning route, please be sure to treat the materials with the utmost respect.

      FIGURE 2-3: Cleaning steel with an angle grinder.

      

The chemicals used to clean steel before welding are caustic and extremely dangerous. They can do serious damage to your eyes and skin. Before using any of these chemicals, be sure you’ve read and understand the Material Safety Data Sheets (MSDS) that lay out their risks. Pay special attention to the ways in which you combine these chemicals because many of them react violently if you mix them up.

      You can clean steel with several different chemicals, and here are a few that you may want to consider.

      

Almost all the solvents used to clean steel and other metals before welding are extremely flammable, so be sure that no spark or flame ever comes in contact with the solvent or its fumes. If you clean steel with one of these solvents, make sure the metal is completely dry and the solvent has evaporated or dissipated before you begin welding. Also, be sure to keep your solvent containers in a safe place away from your welding area, as I note in Chapter 3.

      ❯❯ Acetone: This harsh chemical removes rust and oxidation from steel. Welders usually use acetone by spraying it on and rubbing or wiping it off with a clean rag. Compared to some of the other solvents sometimes used to clean metal, acetone is relatively mild, but it’s still a toxic material, so proceed with caution.

      ❯❯ Alcohol: You can use alcohol for light cleaning and for degreasing. I recommend spraying it on and wiping it off with a clean rag or cloth.

      ❯❯ Acid: You can use sulfuric or hydrochloric acids to remove rust scales and oxidation from steel before welding it. These substances are dangerous, so use extreme caution if you go this route – in fact, I recommend cleaning with acid only as a last resort. After applying the acid, make sure you rinse the area thoroughly with hot water and dry it as soon as possible.

Exploring steel welding methods

      You can weld steel with just about any of the welding methods I describe in this book, but I recommend sticking with the big three arc welding techniques – stick, mig, and tig. Here’s a quick look at a few steel welding specifics to keep in mind for each of those processes.

      Stick welding

      Stick welding works just fine for joining steel. It’s extremely portable – which comes in handy when you need to weld a huge piece of steel that you can’t easily move – and as you can read in Chapters 5 and 6, stick welding is versatile and inexpensive compared to the other welding methods. You can use stick welding on virtually any piece of steel that’s ¹/₈ inch thick or thicker.

      Mig welding

      You can mig weld steel in any position, and that’s one of the reasons mig is the most popular choice for steel welding projects. Another reason: You can get a very smooth steel weld with mig, and you can also avoid a lot of the spatter and waste that you may get with stick welding. You’ll have a hard time finding a piece of steel you can’t weld with mig; very thick pieces of steel work out fine as long you have a powerful mig machine, and you can even weld extremely thin pieces of steel with mig welding.

      Tig welding

      Like mig welding, tig allows you to join all different thicknesses of steel. Tig also affords the advantage of a very clear view of your welding area, because tig produces very little smoke or slag (waste).

      If you choose tig for your steel welding jobs, make sure you have your equipment set up correctly. Ask your welding supply shop for the charts that help you determine the correct amperage, shielding gas flow rate, and polarity for tig welding steel. You also need to be sure that you use the right filler rod (a metal rod that melts and becomes part of your welding puddle to add strength to your weld), or the quality of your weld may suffer greatly.

      

Don’t use oxyacetylene filler rods when you’re tig welding. The copper coating creates impurities in the finished weld.

Going with Stainless Steel

      Stainless steel is pretty incredible stuff. It’s remarkably durable and strong, and as a result it’s used in countless applications all over the world. I doubt you’ll be able to practice welding for long before some stainless steel object catches your eye as a possible project component (if it hasn’t already).

Understanding the differences between steel and stainless steel

      Stainless steel is different from regular steel because it contains 10 to 30 percent chromium. Chromium is added to the steel to create the resistance to corrosion that makes stainless steel so famous (and useful!). Stainless steel can contain a few other substances that make it perform at an even higher level; nickel is the most common.

      Stainless steel today is classified into two general series:

      ❯❯ The 200 to 300 series includes stainless steels made with chromium, nickel, and sometimes manganese. They’re more resistant to corrosion than the 400 series, and they generally have better qualities for welding.

      ❯❯ The 400 series includes stainless steels that don’t contain nickel. They can’t be hardened as much as the 200 to 300 series.

      Stainless steel’s most notable (and desirable) quality is its resistance to corrosion. The combination of steel and chromium creates an outer surface that’s terrific at resisting rust. Because of that quality alone, stainless steel is used in a huge variety of applications, from beer kegs to hypodermic needles to the St. Louis Gateway Arch.

Deciding when to use stainless steel

      Why would you want to use stainless steel in one of your welding projects? Here are a few examples.

      ❯❯ You need part or all of the project to be rust-proof. This goal is pretty self-explanatory, but if your project is going to be located outside – especially in an area that gets