Which Metals Can Be Welded and Why?

Weldability is everything. Metals with a high weldability are easier to weld and retain a higher weld quality than other metals, so it’s important to study these factors before choosing materials for a project.

Once you’ve narrowed down your selection to a few metals, the next step is to determine which welding process you’d like to use. Some methods require more skill than others, such as TIG welding — and these will affect which metals are at your disposal. For example, the ideal metals for MIG welding are carbon steel, stainless steel, and aluminum, all for different reasons.

The main parameters that determine a metal’s weldability include the electrode material, cooling rate, shielding gases, and welding speed. Every metal is unique. To a certain extent, all metals can be welded, but there are clear advantages and disadvantages to each.

Stick welding, also known as shielded metal arc welding (SMAW), is one of the most common welding methods out there. To get started, you’ll need a welding machine, a proper electrode (we recommend DCEP for DC welding), a safety helmet, clamps to hold the joints together, and your welding metal of choice. With this method, you are melting a metal rod with a special flux coating that prevents oxygen contamination — hence the “shielded metal” name. Stick welding can be used to weld steel, iron, aluminum, copper, and nickel.

Unlike stick welding, gas metal arc welding (or GMAW) does not have a coating over the electrode rod. Instead, the welding gun disperses a shielding gas that protects against contaminants. It’s the most common industrial welding process today, and can be used for steel, cast iron, magnesium, and many other metals.

Ultimately, there is no clear-cut answer when deciding which metals and welding methods to use. It’s best to figure out which metals are best suited (and most cost-effective) for your project, and then decide on a welding style that can be performed with your skill set.

Grades of Steel

Around the world, a variety of organizations have developed standards for steel grading, including British Standards, Japanese Industrial Standards, and Germany’s GB Standard. However, SAE International’s steel grading system is the most common. Started in the 1930s as a joint effort between SAE and the American Iron and Steel Institute (AISI), the two designed a number system that is still used today. Here are SAE’s basic designations for carbon and alloy steel:

  • 1xxx: Carbon Steel
  • 2xxx: Nickel Steel
  • 3xxx: Nickel-Chromium Steel
  • 4xxx: Molybdenum Steel
  • 5xxx: Chromium Steel
  • 6xxx: Chromium-Vanadium Steel
  • 7xxx: Tungsten Steel
  • 8xxx: Nickel-Chromium-Molybdenum Steel
  • 9xxx: Silicon-Manganese Steel

How does the number grading work?

These steel alloys are distinguished with a four-digit number. As seen in the list above, the first digit represents the primary alloying element. In some cases, there are multiple elements, such as nickel-chromium-molybdenum steel (8xxx). If there are secondary elements, they are represented by the second digit in the sequence. Here are a few examples:

  • 10xx: Plain Carbon Steel
  • 13xx: Manganese Steel (Mn 1.75%)
  • 32xx: Nickel-Chromium Steel (Ni 1.25%, Cr 1.07%)
  • 34xx: Nickel-Chromium Steel (Ni 3%, Cr 0.77%)
  • 72xx: Tungsten-Chromium Steel (W 1.75%, Cr 0.75%)

Finally, the last two digits in the grading system are devoted to the alloy’s carbon percentage (in hundredths, by weight). If the last two digits are 45, that means the carbon content is 0.45 wt%.

How is stainless steel graded?

Unlike carbon and alloy steels, stainless steel has its own grading system. With three digits instead of four, there are less stainless steel alloys to categorize. Similar to the previous grading method, the first digit represents the primary alloy composition. Here are the main categories:

  • 1xx: Austenitic General Purpose Alloys
  • 2xx: Austenitic Chromium-Nickel-Manganese Alloys
  • 3xx: Austenitic Chromium-Nickel Alloys
  • 4xx: Ferritic and Martensitic Chromium Alloys
  • 5xx: Heat-Resisting Chromium Alloys