How To Weld Thin Steel With Flux-Cored Wire (Step-by-Step)

In Brief: How To Weld Thin Steel With Flux-Cored Wire

To weld thin steel with flux-cored wire, obtain a reference guide from the manufacturer. Set the voltage and wire feed speed to the recommended levels, and adjust downwards to suit. Good values are 14-15 volts and 50-70 inches per minute. Drag the weld and move quickly. Remove the slag with a flap wheel and inspect for imperfections.

If you need to weld thin steel, then your best option will be to MIG weld with solid wire.

However, if you do not have any solid wire available, then it is possible to weld thin steel with flux-cored wire.

Be aware before starting that the weld will not be ideal. But, with a bit of planning and the right setup, you can get an adequate weld.

This guide will show you how to weld thin steel with flux-cored wire.

How To Weld Thin Steel With Flux-Cored Wire

The first thing you need to do is work out what type of flux-cored wire you have.

FCAW-G wire will require a gas shielding setup, so you will need to prepare your equipment for that. If you already have your welding machine set up for MIG welding then you are probably ready to go but make sure that you have the right type of shielding gas for the wire.

FCAW-S wire does not require a gas shielding setup.

You will also need a reference guide from the wire’s manufacturer that will give you guidance voltage and wire feed speeds for your flux-cored wire.

Follow these steps to weld thin steel with flux-cored wire:

  1. Setting Voltage, Polarity, and Wire Feed Speed

    Assuming that you are using self-shielded flux-cored wire which does not require gas shielding, you will be using straight polarity or DCEN as it will appear on your machine.

    Refer to the manufacturer’s guidance for voltage and wire feed speed. As a general starting point, you should use 15 volts and a wire speed of around 70 inches per minute.

  2. Tack The Workpiece

    Secure the workpiece on the welding table or in position if the piece is too large, and tack it together.

  3. Weld

    You can now perform the weld. Remember to drag. Be aware that the high deposition rate of flux-cored wire means that you should work quicker than with other welding processes.

    If you find that you are blowing through the weld, then you will want to dial the voltage back to around 14 volts.

    You can also reduce the wire feed speed to around 50 inches per minute. This will provide a low amperage for a more controlled weld.

  4. Clean the Slag

    Flux-cored wire produces slag, so you will need to chip it off afterward.

    If you need to make multiple passes, you will need to do this after every pass.

    The best way to clear the slag away is to use a flap disc. This will reveal any imperfections. Be especially mindful if using self-shielded flux-cored wire because trapped gas can remain in the weld and cause imperfections.

    For an overview of the various concerns when welding thin steel with flux-cored wire, check out this video:


We hope this guide has helped you to weld thin steel with flux-cored wire.

Although not a perfect solution, in the absence of better solutions you absolutely can achieve an adequate weld on thin steel using flux-cored wire.

If you have any questions or comments about this guide or welding in general, please feel free to leave them in the comments section below.

About Kevin Stewart

Kevin is an expert metal worker with a passion for designing and making. He is passionate about his power tools. He contributes his ideas to various online platforms.

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