Home How To How to Weld Using Flux Core Wire – Step by Step Guide

How to Weld Using Flux Core Wire – Step by Step Guide

how to weld using flux core wire

Flux core is a type of wire which is used in welding machine for welding purposes. These wires are very useful and effective for many welding cases. Flux cored wires are optimized to obtain performance that not possible with solid wires.

Flux-cored welding gives many advantages while welding on construction applications by including high disposition rates and good chemical properties.

What is inside A Flux Core?

These wires are designed in a tube shape. The outer layer of the wire is metal. The inner section is a compound of various materials which are called “flux”.

Flux is designed in a way that when the wire is melted in the arc the compound makes a shielding gas that protects the welding.

Type of flux core:

We can mainly divide flux core wires into two types, Self-shielded flux core wire (FCAW-S) and Gas shielded flux core (FCAW-G) (double shielded)

There are various types of popular flux-cored wires. They are individually good for different cases. Some of the most popular flux core wires are-

  • E71T-1:

    E71T-1 is the most popular and used flux-cored wire in the world. It is the top choice of workers for shipbuilding, general structural and steel fabrication welding. It provides fast cooling rutile slags which are very useful and important for vertical-up position welding. It also gives the smoothest welding arc and minimal spatter.

  • E7T-4:

    E70T-4 offers the highest semi-automatic deposition rates. It gives slightly lower deposition rates than E70T-1, but it offers a smoother welding arc. E70T-4 widely uses in structural steel fabrication shops. It is the fastest flux-cored wire to join a thick steel plate in the flat position (semi-automatic welding).

  • E70T-5:

    E70T-5 gas shielded wire offers excellent crack resistance on hard welding steels. E70T-5 has a slag system, which removes phosphorus and sulfur (sometimes can cause cracking) from the weld metal, porosity, and poor toughness. E70T-5 also has the lowest disposable hydrogen levels among the flux-cored wires which gives excellent resistance to hydrogen cracking.

  • E71T-8:

    For semi-automatic(out-of-position) welding without shielding gas, these wires give the highest deposition rates. This wire is self-shielded, allowing it to be used outdoors easily. That’s why E71T-8 is widely used in outdoors and field erection welding. These wires are widely used to join thick steels where there is no impact of toughness require.

  • E71T-14:

    E71T-14 is a good choice and widely for welding coated and galvanized steel sheets. E71T-14 is a self-shielded wire. This wire has some core materials which allow exploding in the arc which minimizes the possibility of porosity and cracking. E71T-14 is widely used in the automobile industries for fabricating galvanized steels.

Flux core wire sizes:

Flux core Wires are available in various diameters like, 030, 0.035, 0.045 0.068, 11/4,5/64, 3/32 etc. Try to Look at your welder. There will be a minimum and maximum thickness of metals recommendation for your particular welder along with specific sizes of flux core welding wire to use.

How to weld using flux core wire:

There are several steps to weld using a flux-cored wire properly and smoothly. These steps should help you to learn and apply to weld with a professional touch.


Safety is the number one priority for any kind of electric and fire-based works. You should not try welding if you are below 18.

For safe welding, make sure you have the fire-resistant jacket, safety glasses, welding gloves, and an approved welding helmet. Make sure you have enough ventilation (make use of a fume extraction if needed).

Never weld near flammable materials.

Weld Processes:

Flux-cored wire welding uses spools of wire fed through a gun. This constant feeding of wire minimizes starts and stops. This helps inexperienced welders to create good looking joints.

Flux-cored welding uses wire that is specifically designed for use with or without shielding gas depending upon the wire being used. Those designed for use without gas (self-shielded). It is best for outdoor works.

It’s also faster, more economical, and better suited to welding thin sheet metal.

Input Voltage:

There are mostly two choices here (110v and 230v) available for most homes or backyards.

Generally, 110v voltages are enough for thinner materials and 230v is used for welding thicker materials. If you are a beginner, then you might get benefit from a machine that offers dual voltage (both 110v and 230v) so you can try and practice in both voltages.


It can be tricky for a new user to set up welding settings. It is also difficult to understand which voltage and flux-cored wire are needed for which cases. So choose carefully for perfect welding. If you fail, don’t worry, practice will make is smoother soon. Some smart machines automatically choose or help to choose the right wires and voltage for various materials.


placing is very important for any kind of welding. Especially for flux-cored weldings, when your two hands are busy for welding.

Place the two parts on a non-flammable table or workplace. It must be placed where your hands can reach easily to work smoothly. Make sure there are enough light and ventilation. Now place the two pieces very closely where you want to weld. Place them tightly with screws, clips clamps or weights.


Welding is the most important part of work. Because you don’t want to end with a mess up.

After placing sheets and setting welding tools and wearing safety gear, you should stand enough close where you can easily see where you want to weld. Then first use the flux gun and start welding from one side to another side. Never weld jumping from one part to another. Finish by a straight line so the welding becomes more strong and permanent.

Tips for Avoiding Common Flux-Cored Problems:

  • Avoid Wire Feeding:

    wire feeding is a very common problem on welding sites. The two most prevalent types of wire feeding problems are—1. burnback (wire melts like a ball and result in slow wire feeding) and 2.birdnesting(happens when there is a tangle in the wire).

  • Minimize the possibility of Porosity:

    Porosity is a common welding problem. It weak the welding. Porosity results when gas becomes trapped in the weld metal and can appear at any specific point. To prevent porosity, try removing any dust, rust, paint, coatings, oil, etc. and dirt from the base metal of welding.

  • Slag inclusions:

    Slag inclusions happens when the slag generated by the melted flux in the wire’s core becomes trapped inside of the weld. there are several causes of slag inclusions. but they can be prevented with proper welding techniques and awareness.

  • Store:

    Store flux core wire in a dry area and away from water and moisture and keep the wire in its original packaging until you are ready to use it.


  1. self-shielding flux core welding wire produces more smokes and fumes than other welding systems.
  2. Sometime welding can’t match and look less pretty welds.
  3. Self-shielding flux core wire is more expensive to buy.
  4. It produces more spatter then other welding methods.
  5. Flux core wire is not an ideal choice for thin metals, solid wire is a better choice for 24 to 20-gauge mild steel.


Flux-cored wire welding is a very easy and effective welding. Learning it might help you to weld it professionally. Practice making it better for you. It is used in every industry and factories or civil works. Wise choice of flux wire might affect a lot on welding.

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