Are you eyeing a welding project or repair of stainless steel?
If you are a DIY enthusiast, flux core welding can be one welding method you can use.
But you’ve read that flux core welding is commonly used to weld mild steel and not stainless steel, which begs the question: Can you weld stainless steel with flux core?
The quick answer is yes, you can.
In this post, we’re going to talk about why you should use flux core welding when dealing with stainless steel and the wires you can choose from for your project.
What is Flux Core Welding?
Flux core welding was introduced in 1950. Today, the American Welding Association calls this process Flux Core Arc Welding (FCAW).
This welding method is similar to MIG welding that also uses a wire feed, similar equipment, and shielding gas.
But unlike MIG welding that always requires external shielding gas from high-pressure cylinder containers, FCAW may get the shielding gas from the flux core itself aside from the external source.
Shielding gas is the material that protects the molten pool of metal from contaminants.
During welding, the tubular flux-cored wire acts as the electrode, the conductor of electricity to the base of the metal workpiece. As it melts, the flux forms an electrical arc and the shielding gas to protect the weld pool from gases and other contaminants.
A barrier-like casing or slag is also deposited to the metal that helps protect the weld until it cools down. This slag should be removed when the pool cools down. This allows operators to weld materials even outdoors without the risk of contamination.
Benefits of Using Flux Core Welding on Stainless Steel
Flux core arc welding is popular among hobbyists and DIYers.
Portability
The inherent portability of flux core welding is the reason for this preferential treatment. Unlike MIG welding, flux core welding does not require heavy gas cylinders most of the time.
You can even work on your stainless steel project outdoors using flux-cored wire even when windy without the risk of a chemical reaction due to exposure to oxygen, nitrogen, and hydrogen.
Easy operation
Additionally, flux core welding is easier to operate compared to MIG and TIG welding. It only requires little knowledge about the welding machine to start welding, making it an ideal option for owners of home shops and DIYers.
Productivity
The portability and easy operation of flux-core welding ultimately result in a productivity rate cut above the rest.
The Tulsa Welding School said that a flux-core welder deposits 25 pounds of wire per hour, compared to a MIG welder that can only deposit 8 pounds for the same duration.
That’s three times the production rate difference!
This higher production rate can easily translate to faster turnaround times, especially in a home repair shop that constantly tries to meet tight deadlines.
Types of Flux Core Wires
Welding stainless steel using FCAW, and all other welding methods, basically means that you need to be familiar with the different flux-cored wires.
The two varieties of flux-cored wires are self-shielded and gas-shielded.
Self-shielded flux-cored wires, as the name implies, produce their own protective gas arc. Thus, they do not require supplemental shielding gas cylinder containers. This wire type is suitable for outdoor applications. The downside, however, is they produce higher amounts of smoke and spatter.
Gas-shielded flux-cored wires use an external gas cylinder that contains 100 percent carbon dioxide or argon to supplement the weld with shielding gas. Contrary to what one might think, these types of wire are easier to control and give a smoother final texture. The only disadvantage is that welding outdoors is not possible due to weld pool contamination risks.
Recommended Flux-Cored Wire to Use on Stainless Steel
Knowing the two types of flux-cored wires is not enough to get you through stainless steel welding, though. Because selecting the flux-cored wires to use can downright confuse you, especially when you are a newbie.
Essentially, you should first familiarize yourself with the stainless steel you are dealing with to choose the appropriate flux-cored welding wire to use.
All species of stainless steel are divided into four different types:
- Austenitic stainless steel is popularly used for kitchen cutlery and storage components due to its strength and corrosion resistance.
- Ferritic stainless steel is what you see in the car and industrial components, as well as kitchenware.
- Duplex stainless steel, a combination of austenitic and ferritic stainless steel, is used in the underwater oil industry due to extremely high corrosion resistance.
- Martensitic stainless steel is often used in valves or pumps and has an average corrosion resistance capability.
The American Welding Society (AWS) has put forth a classification system for the flux-cored wire to use in welding any of the four types of stainless steel, as well as other metals.
These classifications are solid wire, metal-cored wire, gas-shielded flux-cored, and self-shielded electrodes.
For this post, we will only focus on the flux-cored wires classifications.
Flux-cored wires are designated with alphanumeric combinations, indicating their tensile strength, welding position, nature, usability designators, and classification.
Take, for example, E71TG.
- E stands for electrode
- 7 indicates that the tensile strength is 70 ksi
- 1 indicates the position, which in this case is all position; 0 means flat & horizontal only
- T means that the electrode is a tubular wire
- G stands for the classification, which in this case is “general”
There are several flux-cored wires available in the market, but the popular ones are:
- E71T-1
- E71T-8
- E70T-4
- E70T-1
The E71T-1 is the world’s most popular flux-cored wire due to its incomparable welding capability. It provides smooth welding, minimal spatter, and performance, making it the top choice for general steel fabrication.
If you are a home shop owner of DIYer, E71T-8 will be your best bet when it comes to deposition rates. As E71T-8 self-shielded flux-cored wire, you can carry out your welding projects and repair them outdoors.
Another outdoor-safe flux-cored wire is E70T-4. Widely used in welding thick steel, this wire can deposit 40 pounds of metal per hour, the highest deposition rate among flux-cored wires.
The E70T-1, on the other hand, is a gas-shielded flux-cored wire that offers a smoother welding arc compared to E70T-4. It is commonly utilized in structural steel fabrication shops. But using it in stainless steel is also safe.
Tips on Welding Stainless Steel With Flux Core Wire
When welding with flux-cored wire, remember you should always clean the stainless steel to brush away the chromium buildup and other elements that can render your welding useless in the long run.
Another tip to keep in mind while welding is that you should position the welding gun or torch at an angle of about 10 degrees. Then, use a dragging motion as you progress in your welding. Dragging will enable the flux to rise atop the metal or weld pool, which ensures better coverage.
Final Words
While stainless steel is a tough material to work on, welding is still possible as long as suitable filler metals are utilized, such as flux-cored wires. Do remember, however, that you have to match the filler metal with the alloy constitution of the stainless steel to get good results.
This is why familiarity and understanding of the different types of flux-core are key for a successful stainless steel welding project.
The filler metal user guide by the American Welding Society can come in handy when you want to learn about FCAW and flux-cored wire, providing descriptions of specific filler metals, including flux-cored wire, and their intended usage.
