Filler metals are metals incorporated in making joints through soldering, brazing, and welding. There is a significant influence in filler metal compositions by corrosion resistance of alloy 800H, mechanical characteristics, and microstructure.

Generally, filler metals include Alloy 309, Inconel 82, and Inconel 625. Moreover, filler metals provide in-depth details about the product’s usability and specifications, including the welding positions ability, type of filler metals, chemistry composition, shielding gas, and tensile strength.

What Is The Function Of Filler Material In Welding

functions of welding filler rods
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Filler materials are the particles that get combined with binders and resins, such as concrete, composites, or plastics. The target behind this is to optimize particular properties and make the product affordable or combine both of these aims. The two most prominent elements utilized for fillers are plastics and elastomers.

Filler metals are basically unalloyed and alloyed metals. They are heated, liquefied, and melted to flow within spaces of soldered joints and create brazed or in between two closely fitted parts. Filler metals are suitable for flowing and melting properties so that there’s an even distribution in the prepared joints by the capillary attraction.

Consequently, welding works at the melting point of base metal and requires the base metal to melt. The process requires even heat distribution from small torches as the goal is not to melt the entire metal piece. Therefore, the heat diffusion is effectively controlled rather than barricading the heat limitations to avoid it.

When filler materials accompany the entire welding process, it becomes more well-fitted and tolerant rather than having a poor and flimsy joint. Welding processes are much more accessible and straightforward to manipulate and control, while the material’s edge quality remains less than seamless.

In Which Welding Process Is Filler Material Used

Electric arc welding is a significant filler rod consumer. Filler rods as consumable electrodes generate heat within the required workpiece. The electrode emits electrical discharge, which in return provides the heat needed to melt the base metal and the electrode.

Similarly, TIG welding are also a similar electrical welding process requiring the filler rods to be added manually. The method uses a non-consumable tungsten electrode to provide heat. It’s similar to gas welding, but the heat source is different.

What Is The Material Of Filler Rod

Generally, the most common filler or TIG rods are aluminum, nickel, stainless steel, and mild steel. But the vast array of materials does not end here, and the list is longer in reality. When the intention is to bond the materials, it’s wiser to utilize a filler rod that is of the same metal.

The materials used in filler rods must also meet the ASTM (The American Society for Testing Materials) and the AWS (American Welding Society). In many cases, meeting specific ISO standards are necessary as well.

Furthermore, the materials used in filler rods might also vary based on the project and their demands. For instance, there are mainly four kinds of filler rods that accompany welding. These are welding fluxes, tubular electrode wire, bare electrode rod or wire, and covered electrodes.

Few other non-consumable electrodes may also be in use; however, since these metals are not included or consumed in the welding method, they are not included overall.

What Is The Filler Metal In Gas Welding

The standard materials used in filler metals involve jeweler’s gold, nickel, aluminum, copper, sil-phos, cadmium-free, lead-free, silver, lead, and tin.

Gas welding majorly involves a filler metal and melting the base metal. In other words, the welding torch’s tip produces the flame for the sequential process to work. The molten metal from the filler metal and plate edges intermix with the generic molten pool thus, creating a continuous piece after cooling down.

AWS Filler Metal Classifications:

Getting top-tier results in any welding process depends on the suitable filler material and equipment and the welding operator’s skill set and expertise. If the competition in the market is high and tough to bit, cost and production saving tactics will go hand in hand.

The AWS (American Welding Society) classifications for filler metals give insights about usability and which materials are best suited for which ones, how to use them, and other criteria that combined enrich the overall performance.

In return, these standards are utilized by manufacturers keeping in mind the mechanical, chemistry, and welding point of view.

Other than the classifications, some other essential specifications that act as indicators by the AWS classifications are;

  • If the product specification is either tubular wire, stick electrode or solid wire
  • Its chemistry composition
  • Its classification of strength
  • The position of usage

The AWS classifications can vary based on the base material, flux-cored wire, solid wire, or stick electrodes. However, the specifications in question for filler materials are A5.20, A5.18, and A5.1.

  1. A5.20 or, carbon steel electrode utilized for flux-cored arc welding

One example of gas shielded flux core wire is E70T-1X with an additional designator as C/M, which indicates that wires can be either argon and CO2 or pure CO2. H represents the diffusible hydrogen levels, and J represents the need to improve the material’s toughness.

  • A5.18 OR, Carbon steel electrodes and rods utilized for gas shield arc welding

AWS ER70S-3 are solid wires, and standard filler metals under A5.18 classifications. Under the AWS A3.0, generic welding rods are defined as forms of filler metals for welding that are typically packed and don’t conduct welding currents.

The S represents that it’s one of the solid wire creations. On the same note, solid wires might feature H, which signals that the rod or electrode meets the diffusible hydrogen needs.

  • A5.1 or, carbon steel electrodes utilized for shield metal arc welding

A standard classification under this regime is the E7018 electrode. The positions assigned for this are flat and horizontal only or flat, overhead, vertical, and horizontal. E indicates the filler metal, 70 indicates tensile strength measure in ksi, and 8 shows the product’s coating. Also there are other models like E6013 and many more that works quite good in welding, you just need to understand the requirement for weld your metal as PSI of these electrodes vary.

Filler For Various Types Of Welding:

TIG and MIG operate under the same principle, which translates that the heat generated by electrical currents melt base metals and then cools to form a coherent piece. But, there are some other differences in these cases. Let’s check them out quickly.

  1. MIG

It’s generally used for thicker and larger materials. Moreover, it employs consumable wires, which function as filler and electrode materials. MIGs are much faster, resulting in less production cost and lower lead time.

It’s also more accessible to create and learn welding that demands less to no finishing and cleaning. Unfortunately, the welds are not neat, solid, and precise, unlike TIG.

  • TIG

These are industry-level, highly professional thin, and trim materials. It utilizes non-consumable electrodes to heat metals and doesn’t necessarily require a filler.

TIGs are much slower, resulting in higher production costs and prolonged lead hours. Welders also need special training to improve their accuracy and precision. Even with these hassles, TIGs offer the greatest control with neat, aesthetically precise, and sturdy welds.

What Is The Difference Between Filler And Electrode In Welding

In this phenomenon, the electrode is the element of the welding torch that must strike the arc to function.

On the other hand, the filler metal is the metallic wire utilized to fill gaps between the joints and the base metals. And it’s not a part of the electrical circuit or electrode.

Can You Weld Without Filler

Welding without a filler metal is quite common in autogenous welding. This is a form of welding where filler metals are either supplied through identical composition or the melting of the base material.

The production of these forms of welding emphasizes the base metal’s melting without the use of any filler rods. However, there are a few variations in their benefits too.

How To Choose The Right Filler Metals

Choosing the suitable filler material will diminish the work’s chances of defects, corrosion, and cracking. Hence, we must consider a few factors during filler metal usage.

  • Base Material –

One must comprehend which filler metal suits which base material best. Both the materials must have the same properties and strength for optimized results.

  • Position

Welding in a flat position is the best economically accepted method. However, other positions such as overhead, vertical and horizontal can’t be ruled out either. Similarly, changing a welding’s position is viable if done gradually and with the highest efficiency.

Therefore, selecting a versatile size and type of filler metal should do the trick.

  • Regulations –

The specifications and classifications dictate which class or wire to use. Other considerations that welders must heed are those accompanying the service requirements and conditions so that the welding remains long-lasting and sturdy.

  • Shielding Gas –

If the shielding gas and filler metals are not compatible, the entire project will be at a loss. Each shielding gas has varying influences on filler metals, which needs review.

Last Words

The bottom line is that welding operators need correct direction under regulatory bodies and the AWS classifications to operate precisely and safely. Meeting the service conditions so that the final products become desirable is the overall goal of any high-tech industry working with welding and its other vital components.

Therefore, it is necessary to choose the correct filler metals for specific jobs, know their capacities, classifications, and functionality. It’s a no-brainer that when filler metal welding require such extensive overviews and know-hows, industries and their welders need adequate guidance and detailed instruction to maintain highest safety standards.


Maidul Islam

Maidul Shakil has an extreme love for welding. Welding metals and joining them is his hobby and he has also got a vocational training on welding. He strives to learn and teach welding processes and different gears to beginners and newbies. Cutting metal, fusing them and polishing to a shiny surface seems interesting.