Best Welding Wire for Mild Steel When MIG Welding at Home

By Bill Byers / March 8, 2019
Best Welding Wire For Mild Steel

Can mild steel be welded? Yes

It most certainly can and I’ve researched for you here the best welding wire for mild steel for the home work shop, garage or on the ranch.

I’ve compared here mild steel MIG wire, which needs shielding gas as opposed to flux core wire for mild steel that is most often self-shielded.

Best Welding Wire for Mild Steel Revealed

1. INE INEFIL ER70S-6 Mild Steel MIG Welding Wire (*Paid Text and Image Link)

  • Wire Diameter size 0.023 or 0.030 or 0.035 inch
  • Weight Available in 2 lb. spool or 10 lb. spool
  • Shielding Gas: 80% Argon 20% CO2 or can be used with C25 or 100% CO2 shielding gas
  • Welding Positions: An all position wire that supports single and multi pass welding
  • A well priced wire with very good Amazon feedback

2. Hobart ER70S-6 Mild Steel MIG Welding Wire (*Paid Text and Image Link)

  • Wire Diameter size 0.024 or 0.030 or 0.035
  • Weight Available in 2 lb. spool or 10 lb. spool
  • Shielding Gas: C25, or 100% CO2
  • Welding Positions: An all position wire that supports single or multi pass
  • Lots of Good Amazon feedback apart from some broken spools from shipping. Note that this wire isn’t manufactured in the US but in China.

Consider buying with this wire Hobart Contact Tips, Hobart multi function welding Pliers or Hobart MIG Nozzle Gel. (*Paid Links)

3. Blue Demon ER70S6 Mild Steel MIG Welding Wire (*Paid Text and Image Link)

  • Wire Diameter Sizes: 0.023, 0.030, 0.035
  • Weight Available: 2lb spool or 11 lb. spool
  • Although the spool size says 11 lb. it will fit in a welder that can take 10 lb. spools. Check spool diameters size.
  • Shielding Gas: C25,
  • Welding Positions: F, V, OH H – Flat, Vertical, Overhead, Horizontal
  • Good Amazon Feedback, with some issues with broken spools on delivery.

4. Forney ER70S-6 Mild Steel MIG Welding Wire (*Paid Text and Image Link)

  • Wire Diameter Sizes: 0.024 or 0.030 or 0.035
  • Weight Available: 2 lb. spool or 10 lb. spool
  • Shielding Gas: C25 or 100% CO2
  • Welding Positions: an all position wire that supports single and multi pass welding
  • Not as much Amazon Feedback as the above wires but what there is generally good barring the usual box, spool, shipping issues. The wire is very well regarded as excellent welding wire in the home welding and industrial market.

How about considering getting some Forney Contact Tips (*Paid Link) with this wire?

Note: These wires are available in larger diameter sizes and spool sizes. I have chosen the wires and sizes above as they are most often used by the home work shop welder.

Low Carbon Steel Welding

Low Carbon Steel Welding

Home MIG Welder – What are the needs to know When Welding Mild Steel?

The first principal when choosing a welding wire – also known as the filler metal is that the metal should be the same as the base metal to be welded.

Welding mild steel (also known as low carbon steel) you will need mild steel wire.

Selecting to MIG weld mild steel with solid wire and gas instead of flux core is done when you want a nice looking weld and the finish is important to you.

MIG welding is an inside process unless you have a special set up to prevent wind getting to your weld and blowing your shielding gas away outdoors. And where you have clean metal or metal that can be adequately cleaned for a good weld.

What is Mild Steel?

Mild steel or Low Carbon steel is a very common metal that is cheap and easy to form. It has properties that make it amenable to a wide variety of applications.

Mild Steel contains 0.05% to 0.025% Carbon – a low amount of Carbon.

MIG Welding Wire of Choice The ER70S-6 Standard

ER70S-6 is a good all purpose MIG welding wire for use with low carbon and mild steel. The ER70S-6 MIG wire has extra flux content, which includes levels of Silicon and Manganese.

The Silicon and Manganese acts as deoxidizers allowing you to weld metal that isn’t quite clean. Light dirt or rust are better tolerated by this wire and are eaten up by the arc or are trapped and appear as ‘Islands of Silicon’.

Weld With Silicon On The Top

The production of islands of silicon on the welded surface can then be easily removed and must be chipped off by your chipping hammer if they are not to cause the flaking off of any subsequent painting.

Be sure to wear safety glasses as you chip at these shards of Silicon. They have a nasty habit of finding a new home in your eye causing an unexpected trip to the emergency room.

In addition ER70S-6 wire is often thinly plated with copper to help prevent the rusting of the wire before the wire gets to you and to aid in electrical conductivity as you weld.

With the right settings ER70S-6 should give you a nice clean weld, needing little slag clean off and a weld that is ready to paint.

YouTube Video about the Best Type of MIG Wire

This YouTube video from weld.com where the tutor of Cowley College, Ark City, Ks. discusses the ER70S-6 and why it is the best general purpose MIG wire when MIG welding mild steel. I hope you enjoy it as much as I did.

What is the Best Overall MIG Wire

Video Credit: Weld.com

What does the ER70S-6 stand for in Welding Wire?

According to the American Welding Society standards,

the E and the R means the filler wire is either an Electrode or Rod. An electrode wire is used for MIG welding.

The figure 70 means it has a tensile strength of 70,000 pounds per square inch.

S means that it is a solid wire as opposed to flux core.

6 means that it has Silicon and Manganese as deoxidizers

This wire is used widely for welding low carbon and mild steel parts in and around the home, ranch and industry as well as for car and automotive repair.

Choose a Good Brand and Wire

Selecting a good MIG wire from a quality supplier could well save you time and much frustration.

Well known brands ensure their wires meet the minimum tensile strength set by the wire standard committee of AWS (American Welding Society).

They ensure the wire quality and diameter is accurate and consistent throughout the spool.

Who wants their weld ruined and porous because parts of the spool are chemically wrong or the diameter has increased and is now causing feeding problems or is thin enough to break in your welder.

A good brand wire is more forgiving of the cleanliness of the metal and skill of the welder.

Mild Steel Solid MIG Wire

Good Quality Mild Steel Solid MIG Wire

On the Subject of Clean Metal

It’s not that you don’t need clean metal with these wires as you MIG weld (it is always best to clean and prepare your base metals as well as you can).

Clean means, a base metal that is as oil and paint free as you can make it.

Grind and/or brush to remove rust where you are welding.

It is best to get your metal so clean so that you can see bare metal, then you have the best surface possible for your weld.

When attaching your work clamp to your work piece, make sure the surfaces of the clamp and where the clamp connects to your work piece is also clean.

That way you ensure good contact with your work piece. Welding is an electrical process and good electrical contacts are crucial.

What is the Best Shielding Gas for MIG welding Mild Steel?

The best welding gas to use when MIG welding low carbon steel is C25. C25 is a mix of 75% Argon gas and 25% Carbon Dioxide gas. This is the most popular mix of gas as it reduces spatter and results in a great bead appearance.

Argon/CO2 Shieding Gas Cylinder

Argon/CO2 Shieding Gas Cylinder and Regulator

Some low carbon steel welding wires will also weld well or better with 80% Argon and 20% Carbon Dioxide. It is always worth checking the manufacturer’s welding parameter chart for the wire to see what they recommend for the best weld.

There are the welder fans of 100% Carbon Dioxide. It is a good choice as it is a cheaper gas to buy. You will need a regulator suitable for Carbon Dioxide gas. Do not try to use an Argon gas regulator, as it won’t work.

Carbon Dioxide gas is better when good penetration of the base metal is important though it is well known for producing a lot of spatter.

And producing welds that look rough.

But where you were welding thicker metals where deep penetration is needed and you’re not that concerned about the look of the weld. Not to mention the clean up of spatter then CO2 could be for you.

The ideal shielding gas flow rate for welding Mild Steel is 20 to 25 cubic feet per hour.

Storing your Welding Wire Well is Important

Check when your new wire arrives that the seal around the wire isn’t damaged exposing your wire to the air.

Any sign of rust on your wire and the spool should be returned for a replacement as rust on your wire will give you feeding problems with your welder as well as changing the electrical characteristics of the wire contributing to poor welding and could even lead to weld failure.

When you have finished welding, remove unused wire from your welder and store.

Ensure the wire is stored well, sealed and not exposed to the air where exposure could cause rusting of your wire and mean that the wire has to be discarded.

You definitely do not want your welding wire rusting in your welder or in the hose to your MIG gun or within your wire feed mechanism of your welder.

That will cause you a world of pain to clean out and result in you needing to replace the liner in your hose and contact tips unnecessarily.

Welding Wire Size Selection

When choosing your mild steel wire a couple of things need to be kept in mind as you choose.

  1. Check what diameter of wire your welder will feed. There is no point purchasing 0.023 wire for welding thinner metal if your welder is unable to feed it. It is important to choose the right diameter size wire for your welder and the roller you are using. It’s the same at the other end of the spectrum don’t buy 0.045 diameter wire if your welder can’t feed that diameter of wire. A diameter of wire that is too wide causes to much effort for your welder to feed correctly and can block in your contact tip.
  2. When selecting wire, if your welder is flux core only then using MIG wire is no good to you. This is because flux core comes with flux inside the wire that provides the shielding gas as you weld. MIG wire needs separate shielding gas or you will get an extremely poor weld.
  3. Generally use thinner MIG wire for thin metal and thicker MIG wire for thicker metals. 0.023 or 0.024 wire is for thinner metal (24 gauge to 14 gauge) to reduce heat input and the risk of blowing through your base metal.

Welding 1/4 inch and thinner gauge (16 gauge and up) mild steel then 0.030 wire is a good all purpose choice. Welding 3/16th then 0.035 diameter wire is better or where you have gappy uneven weld joint and 0.035 is helpful to fill up the joint.

With a home welder welding thicker metal multiple passes will probably be needed. Welding multiple passes means that you need to source a wire that is tolerant of that kind of welding – certified for multi pass welding.

  1. Select the wire size you are using and match the size to your contact tip. Feeding small diameter wire such as 0.023 or 0.024 with 0.035 contact tip can cause arcing with your welding contact tip.

General Wire Size Tips

Feed from the correct slot on your roller, choose the correct matching size contact tip and select quality wire where wire diameter tolerances are controlled and are the correct size.

In addition, be led by what your welder recommends as those will be the tolerances of your particular brand of welder.

Should your welder only feed 0.024 or 0.030 or 0.035 then choose those wire diameters.

Check your welder’s welding parameters chart and compare them to the data sheet or welding parameters chart of the wire to ensure your welder can produce the Amp necessary to weld the gauge and type of mild steel you are looking to weld.

Low Carbon Steel Weld Pool

Low Carbon Steel Weld Pool

Choosing Your Spool Size

When buying MIG wire there isn’t just the wire diameter size to take into account. There is also the spool size.

No point buying a 10 lb. spool if your welder isn’t able to hold a 10 lb. spool.

Or your welder may need an adaptor to take a larger spool – do you have that to hand or will you need to purchase one?

If your welder can take larger spool sizes then the cost per lb. of wire will be cheaper and worth looking at – assuming you’ll use the wire.

Welder can take a 10 lb. spool?

Check the spool diameters – you may find you can use an 11 lb. spool just as easily and get an even better price per lb.

Also if you are mainly welding flux core and MIG welding little and only occasionally then a 2 lb. spool may be just fine for you. Then you don’t have to worry so much about correct storage of your wire as you’ll use what you weld.

Polarity

MIG welding mild steel wire means that your welder needs to be set on DCEP (direct current electrode positive. That means your MIG gun needs to be connected to the positive terminal in your MIG welder.

It is worth double checking particularly if you weld mainly with flux core and only occasionally MIG weld. The wrong settings will cause a poor weld.

Last Words

Thank you for making it this far in my article, ‘Best Welding Wire for Mild Steel, When MIG Welding at Home’. I hope you found the information here useful and I wish you happy welding.