Welding Filler Metals & Rods

The best filler metal for welding depends on the base materials you’re working with and the welding process. For example, for mild steel, ER70S-6 is a popular choice for MIG welding, while ER308L is commonly used for stainless steel. TIG welders often use ER316L for welding stainless steel, and for aluminum, ER4043 is a good option. Make sure to match the filler metal to the base metal and welding technique.

Yes, you can weld 304 stainless steel with 316 filler metal, but it is not always the best choice. 316 filler metal contains molybdenum, which improves corrosion resistance, especially in chloride environments, but it may not be necessary for welding 304, as 304 itself is corrosion-resistant. For most 304 welding jobs, using 304 filler metal is preferable unless the application demands the additional properties of 316 filler. 

In MIG welding, the most commonly used filler metals are ER70S-6 for mild steel and ER308L or ER316L for stainless steel. For aluminum, the ER4043 or ER5356 filler metals are often used, depending on the specific alloy being welded. Filler metal selection in MIG welding is crucial for achieving the desired strength and durability of the weld.

The strongest filler rod typically depends on the material being welded and the welding process. For example:

• For stainless steel, ER309L or ER316L rods offer great strength and corrosion resistance.
• For aluminum, ER5356 is known for its strength and excellent crack resistance.
• For high-strength steel, ER80S-D2 is commonly used. These rods are specifically formulated to maintain the integrity of the welded joint in harsh conditions.

Choosing the right welding filler depends on several factors:

• Base Material: Ensure the filler is compatible with the base metal being welded.
• Welding Process: Different welding processes (MIG, TIG, Stick) may require different filler metals.
• Strength and Corrosion Resistance: Consider the strength requirements and environmental factors, such as exposure to chemicals or high temperatures.
• Compatibility: Match the filler metal to the grade of the base metal for the best results.
  Always consult the welding procedure specification (WPS) or manufacturer guidelines for the optimal choice.

Both 6010 and 7018 electrodes have specific advantages based on the application:

• 6010: This electrode is best for deep penetration welds and works well with low-temperature materials or in situations requiring fast-paced welding. It’s often used in pipeline welding and for vertical or overhead positions.
• 7018: Offers smoother welds with better mechanical properties and is ideal for structural and general-purpose welding. It’s commonly used for more critical applications requiring high strength and ductility. The choice depends on the requirements of your project and welding position.

While it is technically possible to use a stainless steel filler for mild steel, it is not recommended unless you need specific properties like higher corrosion resistance. Using a mild steel filler metal, such as ER70S-6, for welding mild steel ensures stronger, more durable welds. For standard applications, always use the filler metal designed for the base material to ensure the best weld quality.