You've got broken stainless steel that needs a weld.
A guy quoted you big bucks to TIG weld it. But you have a welder ...
Your local welder supply is happy to sell you some Tri Mix gas to weld it with but its some huge cylinder and you'll never use all that. And the price they quoted you is way more than you planned on spending.
But I do I have to use a tank of gas? I hear you say ...
Can you weld stainless steel with flux core wire?
Yes! If you search for stainless flux core wire.
And if you do find it ... can you flux core weld stainless steel when you have a home MIG welder?
Yes perhaps. Let me explain.
The Usual Advice
Most advice and books you read will tell you that if you want to weld stainless steel you have to MIG or TIG weld it. And you're going to need solid stainless steel wire and shielding gas - preferably Tri Mix (90% Helium, 7.5% Argon, 2.5% Carbon Dioxide) to weld stainless steel with and largely that is true,
But, there is another option: stainless steel flux core welding wire.
Available Stainless Steel Welding Wire That Is Flux Core
The company Blue Demon sells gasless stainless steel flux cored wire that is readily available on Amazon and Ebay. And user feed back is largely positive.
There are other, not particularly well known brands of welding wire on Ebay, that claim to be gasless stainless steel flux core wire. There isn't as much feed back on those brands and some complain that when the wire arrived it was stainless steel all right but not flux cored.
So the wire may not be what you think it is or as advertised.
And to be honest after an extensive search on and off Amazon and Ebay the Blue Demon wire seems to be the main option for flux cored stainless steel welding wire, that is gasless on-line.
If you do find some other decent brand do let me know in the comments - I'd be interested to take a look at it.
Blue Demon Stainless Steel Welding Wire Flux Core Filler Wire Options
Reasons to Buy:
Wire with good user feed back.
Will weld all 300 series stainless steel up to 308 and will also weld those 430 stainless steel parts.
Reasons Not to Buy:
The 308LFC welding wire is not an all positions wire.
It is rated for F and H - flat and horizontal welding positions.
If you are welding up an exhaust overhead then this wire isn't for you. You'll get yourself covered in spatter.
Other Key Info:
308LFC the 1 lb spool comes in around ten dollars more expensive than a similar roll of non flux core stainless steel welding wire.
Is available in 0.035 inch diameter size which many home 120 volt welders use. Is also available in 0.045 inch diameter size.
You will need a minimum of 130 Amp up to 150 Amp welding output from your welder to weld well with this filler wire.
Reasons to Buy:
Good user feed back.
The Blue Demon 309L Flux Core wire will weld 300 series stainless steels up to 309. Will also weld 309 stainless steel to 309 stainless steel. It is a useful filler metal as it will weld 300 series stainless steels up to 309 to other mild steels. So if you are looking to join stainless steel to mild steel this filler wire is the one to use.
Reasons Not to Buy:
The 309LFC flux cored stainless steel welding wire is not an all positions wire.
It is rated for F and H - flat and horizontal welding positions. You'll need to get that repair part positioned so that you can do a flat or horizontal weld.
Other Key Info:
Available in 0.035 inch and 0.045 inch diameter size.
You will need a minimum of 130 Amp up to 150 Amp welding output from your welder to weld.
Reasons to Buy:
Good user feed back.
Blue Demon 316FC-O for 316 stainless steel (which is a food grade stainless steel).
Reasons Not to Buy:
The 316FC-O welding wire is not an all position wire.
It is rated for F and H - Flat and Horizontal positions
Other Key Info:
Available in 0.035 inch and 0.045 inch diameter size.
Will need a minimum of 130 and up to 150 Amp welding output from your welder to weld this wire well.
Along with your Blue Demon 308L, or 309L and 316L consider getting yourself a tub of Hobart anti spatter nozzle gel to keep your welding nozzle clear, just in case you get some BB's.
Or some Anti Spatter spray for around the joint to aid in spatter clean up.
If you are not sure what nozzle gel is or what anti spatter spray is and want to know more - check out my article on the site.
Observations on Blue Demon Stainless Steel Flux Core Wire
Buying the Blue Demon stainless steel gasless flux core filler wire is more expensive when compared to solid stainless steel filler wire.
But stainless steel solid wire needs shielding gas to weld it with and Tri Mix is often the shielding gas of choice.
But when you factor in the cost of a tank of Tri Mix gas on top of the solid stainless steel wire, the cost of the self shielded gasless wire doesn't seem so bad.
Tri Mix gas is expensive - can you justify the cost for your project?
You may not be able to source the gas in your area or you may not be able to store or transport a large cylinder.
Note you buy the Tri Mix tank pre mixed. Don't try and mix the gasses yourself.
The Blue Demon gasless flux core wire is for home shop use.
0.035 inch diameter or if you can get is 0.030 inch is the wire size to use for a home welder running on 120 volts. The Blue Demon gasless stainless steel is available in 1 lb. and 2 lb. spools perfect for occasional home garage use.
Though your practice sessions and finding the right settings on your welder may quickly run you through a 1 lb. spool before you have got to the actual job in hand.
There are other types of stainless steel flux core wire, including ones that Blue Demon sells that require shielding gas and I'll cover those later.
Reasons for Seeking out Gasless Flux Core Stainless Steel Wire
There are some great reasons for seeking gasless flux core stainless steel welding wire. And some of your reasons could be because;
1. You need to weld stainless steel outside.
Outdoors the wind can blow away your shielding gas. You know that Tri Mix gas you spent a fortune on. It can be blown away leaving you with a bad weld. MIG welding (using solid wire and shielding gas) is typically an inside process for this reason. Or you will need a wind shield setup of some description to MIG weld out in the open.
2. There is the cost of a gas set up to be factored in. That means, a MIG welder that is capable of providing the welding output needed, a gas hose, the gas cylinder itself and a suitable regulator for the Tri Mix gas.
3. What if you are only welding stainless steel occasionally or a single small project, do you really want to go to the extra costs?
4. Sourcing Tri Mix in small cylinder sizes is difficult.
5. You may not have the space to store the Tri Mix cylinder or you may not have the means to transport it.
Most people don't realize that flux core welding stainless steel without gas is even a thing.
Other Important Points When Welding Stainless Steel Flux Core At Home
Stainless Steel Solid Wire vs Stainless Steel Flux Core
It's worth taking a few seconds to understand the difference. Solid stainless steel welding wire is, well, solid.
Sounds obvious I know but it's an important point.
Shielding gas i.e. typically Tri Mix is needed to protect your weld from contamination from the surrounding air. Contamination that would lead to a poor weld and that is why a gas is needed.
But what if I don't have a welder that will use gas?
The alternative is self shielded flux core wire (also known as gasless flux core wire).
Flux core wire has the metal around the outside (flux core welding stainless steel wire has stainless steel around the outside) and flux through the middle. This flux melts as you weld and the compounds form a gas to shield your weld.
This is a brief description of flux core wire. If you would like to know more I have a document here all about it.
What kind of Stainless Steel Do You Have?
The first step in deciding what you can use to weld your piece with is to establish what kind of stainless steel you have. The steel you are welding is called the base metal.
300 series stainless steel is the most widely manufactured and used.
For example, there is type 304 also known as 18/8. There is type 308, and 309.
Type 316 is generally used in the Food and Drink industry, as these steels do not taint the taste of the food. And these steels are easily cleaned and sterilized for holding food and beverages.
If your stainless steel is magnetic then it may be type 409, which is typically seen in car exhausts.
Type 430 is used in washing machine interiors, refrigerators, dishwashers. etc. These forms of thinner steels (e.g. type 430) are more difficult to weld as welding can crack their structure.
This change in structure can result in something called weld decay. Weld decay causes the weld to rust and fail over time. The last thing you want with stainless steel.
And even though your steel may not look like it needs a clean before you weld, it is a good idea to check for and clean off any oil or grease. And prepare the surface with a grinder using a stainless steel compatible disc.
Choosing your Flux Core Welding Stainless Steel Wire
It is important to know what kind of steel you are dealing with as then you can source the correct welding wire to use as filler material.
Match type 308L with type 308 base metal. The L after the stainless steel flux core type number stands for low carbon. Low carbon stainless steel flux core filler metal helps prevent weld decay so look for that designation on your stainless flux core welding wire.
Type 308 wire will also weld most 300 series stainless steel up to type 308.
Type 309 flux core welding wire for stainless steel will weld 300 series stainless steels up to and including type 309. It is also suitable for welding type 300 series stainless steels to other mild steel.
Type 316L stainless steel will weld 316 stainless steel. Type 316 stainless steel is a special steel as it is classed as food grade and is used in the food and drink industry. It takes skill to weld type 316 well and welding these types of steels is usually done by a professional.
A weld that leave tiny gaps or dips or holes where microbes can live and multiply is disastrous in a container storing food or on a surface where food preparation is conducted. 316 needs to be welded with care.
Do check the welding parameters chart of your stainless steel flux core filler metal to check the stainless steels the manufacturer says their filler metal will weld.
MIG Welding Stainless Steel with Flux Core Wire
You may not have realized this but there are two types of flux core welding wire.
When MIG welding stainless steel flux cored you need the type of flux core wire that needs shielding gas. It is called gas shielded flux core wire (FCAW-G) which is also referred to as double shielded.
This type of stainless steel welding wire doesn't necessarily need Tri Mix for shielding and could support other shielding gases. Check what the manufacture of the welding wire supports for that wire.
Of course you will need a true MIG set up to use those wires - that means a MIG welder that will allow you to feed separate shielding gas.
The gas shielded stainless steel flux core wires produce great welds. The wire is overall more expensive to buy and use. They also tend to be supplied in larger wire diameter sizes and need a welder that will feed that wire and one that has the output to melt and weld it well. Typically a 230 volt MIG welder.
Gasless Stainless Steel Flux Cored Wire
The other type of flux core wire for stainless steel is self shielded stainless steel flux core. Also referred to as gasless flux core welding wire. No separate shielding gas is needed and so it is very convenient for the occasional user or hobbyist welder to use.
Important Considerations When Sourcing Flux Core Wire for Stainless Steel
One thing to pay attention to is the size of wire diameter you buy. No point buying 0.045 inch diameter wire when your flux core welder will only feed 0.035 inch or smaller.
Its also true that there is no point buying a 25 pound spool because that is the minimum spool size the wire comes in, when your welder can only take a maximum of a 10 pound spool.
Because you can't feed it and you need to ensure you store it well.
And don't even try to transfer to a smaller spool because these spools are precision wound and you'll end up with a rats nest of wire.
Stainless flux core welding wire is more delicate than stainless steel solid wire. It doesn't need a spool gun to feed it but rough handling will break the wire.
You need your home flux core welder to be capable of generating enough heat output. And that means a true 90 Amp plus, preferably 130 Amp or more.
You will also need your flux core or MIG welder sent to DCEP polarity. More on that later.
What if I Have a MIG Welder?
Fantastic, You have the choice to MIG weld with solid wire and gas or flux core weld with gasless stainless steel wire.
Or if your MIG welder is powerful enough you can feed shielding gas and use gas shielded flux core stainless welding wire.
Choose your solid stainless steel wire well as some will support C25 (75% Argon/ 25% CO2) or other high Argon gas blends or 100% CO2 as shielding gasses.
For those of you who want to avoid buying an extra bottle of gas (Tri Mix).
Hobart sells Fabco stainless steel flux core welding wire, which is a gas shielded flux cored wire, which can be shielded with C25 gas.
Can You Weld Stainless Steel with Mild Steel Flux Core Wire?
You may well be thinking of this alternative seriously: Of using flux core wire designed for mild steel to weld stainless steel.
Particularly if you have a home flux core welder that runs on 110 volts, because on those welders you may not be able to change the polarity to weld flux core stainless welding wire.
The answer is yes you can.
Stainless steel is steel with special properties.
Stainless steel is often used on items that need to live out side. Items that you don't want to rust. As the name implies stainless steel is used to prevent staining and attack from certain acids - like the ones found in foods for example.
The big but is.
Welding stainless steel with mild steel flux core wire will produce a weld that rusts.
Plus melting the stainless steel base metal to welding point takes a lot of heat output. Your welder must be capable of producing at least 90 Amp of output, preferably more.
To prevent your weld rusting you will need to paint over the mild steel weld with an anti rust or rust resistant coating.
What If the Mild Steel Filler Metal is in Contact with Food?
Stainless steel is used in the food trade where steel needs to come into contact with food. Stainless steel is used because mild steel taints the taste of the food.
Lets talk through an example;
Of using mild steel flux core filler wire to mend a stainless steel barbeque.
If the weld comes into contact with food, you may not be able to put a suitable food grade protective coating on the weld. Or the protective coating may not be heat resistant.
You then face the prospect of scrubbing any rust off before using your mended barbeque and putting up with the taste enhancement!
Setting the Correct Polarity is an Important Issue
If your welder is a cheaper flux core only welder, the question you may be asking is: Can I weld stainless steel with a gasless MIG welder?
Some of the cheapest gasless welders have MIG in their title but they do not feed shielding gas. They often also claim to weld stainless steel but it is unlikely.
First check that your machine can reverse its polarity.
As many cheaper low amp flux core welders will weld with mild steel flux core welding wire. That wire runs on DCEN polarity - Direct Current MIG gun Negative.
Stainless steel flux core welding wire Must Be run with DCEP polarity - Direct Current MIG gun Positive.
Trying to weld flux core wire stainless steel on a DCEN only machine will simply not work.
I think some of the negative feed back on welding stainless with flux core wire reflects the folks who have tried to do this.
Have you a Home Welder That is Up to the Job?
Assuming you have your flux core or MIG welder at home plugged into an exclusive 20 Amp or 30 Amp circuit (have nothing else plugged into the circuit when you have your welder running so that you get the maximum Amps available)
You need a welder that can produce a true 90 Amps. Preferably the 130 Amp minimum most stainless steel flux core welding wire specifications asks for.
Your machine needs to produce enough amperage to melt the wire and the stainless steel base metal. Welding stainless steel with flux core wire needs a decent amount of heat output from the welder to weld well.
If you are using a 110 volt welder you will need to set your welder to its highest setting and keep the wire speed relatively slow.
And then for the cheapest 110 volt welders this will mean a very short welding time. As the duty cycle for the highest Amp settings will be low.
YouTube Video Showing Blue Demon Flux Core Stainless Steel Wire
I found an excellent YouTube video on welding stainless with flux core that I hope you will enjoy. If you have not welded stainless steel flux core before it will set you up nicely.
In the below nine and a half minute video Bob Moffat, welding instructor observed while welding stainless steel with flux core wire;
He saw a ball or bubble effect on the end of the flux core stainless steel wire, which is different to welding with mild steel flux core wire.
This bubble effect is due to the different electrical characteristics stainless steel flux core wire has as opposed to mild steel flux core wire.
The weld sounded strange not the usual sizzle sound you would expect to hear welding mild steel. But that is to be expected. Welding stainless steel flux core sounds different.
He welded 10 gauge stainless steel in a fillet weld
1/4 inch stainless steel bent to allow a view of how the wire does on a corner fillet weld, inside and out.
He ran the wire hot and went a bit faster.
Your welder has to be capable of DCEP reverse polarity.
You need 3/4 to 1 inch stick out - as recommended by the wire welding parameter chart.
He tried pushing into the corner and then pulling into the corner to see if the different welding methods generated more spatter or affected the weld produced.
He saw no excessive spatter.
I think you'll agree the welds look impressive.
The advantages: The flux core wire stainless steel welded well. No need to use separate shielding gas so would be great for occasional use when you have a small job to do and of course for an out door weld.
Have a look at the video here.
Stainless Steel FCAW without Gas
Video Credit : Weld.com
My Search for Other Brands Of Stainless Steel Welding Wire Flux Core
Here are some other brands I found in my search flux core welding wire for stainless steel.
ESAB sells Core-Bright 308L, 309L, 316L flux core stainless wire which is self shielded. Minimum diameter 3/32 and will need a welder capable of producing 350 Amp plus to weld.
Lincoln Electric Blue Max stainless steel 308L, 309L and 316L flux core. An all position welding wire. Gas Shielded will need 98% Argon/2% Oxygen shielding gas. 0.035 inch diameter size available, a minimum 33 lb. size spool.
Kobelco PremiArc stainless steel 308L, 309L and 316L flux core wire. Gas shielded will run with C25 (75/25 Argon CO2 mix). 0.045 inch minimum diameter size and is available in a minimum 33 lb. spool.
Hobart sells Fabco flux core stainless wire. It is an all position welding wire. 308L, 309L and 316L gas shielded. Will use C25 (75/25 Argon CO2 mix) shielding gas and 100% Carbon Dioxide shielding gas. 0.045 inch minimum diameter size. A 28 lb. spool is the smallest spool size.
And there you have it the best of my research into stainless steel welding wire flux core. I hope you can benefit from my research and that I have saved you some time and helped you find what you are looking for.