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The strongest type of welding is the one that fully fuses the joint with a filler metal rated at or above the strength the part needs. For most steel work, TIG, MIG, stick and flux core can all reach the same 70,000 psi filler rating, so procedure and skill decide the winner more than the process name.
In factories, friction stir welding and electron beam welding make some of the best joints on hard-to-weld metals. Those processes need large, purpose-built machines, so they rarely matter for a home shop or a farm repair.
A 70 ksi stick rod and a 70 ksi MIG wire carry the same minimum tensile rating under AWS rules. The real differences come from penetration, heat input, shielding gas, joint design and how clean the metal is.
Strongest Type of Welding: The Short Answer
No common arc process is stronger by default. Hobart Brothers states that two filler metals in the same AWS tensile class, such as a 70 ksi stick electrode and a 70 ksi solid wire, have the same minimum tensile strength. The strongest weld is the one with full fusion, sound metal and the right filler for the base metal.
Here is how the 4 main arc processes compare on mild steel:
| Process | Common mild steel filler | Filler minimum tensile rating | What usually weakens the weld |
|---|---|---|---|
| Stick (SMAW) | E7018, E6011 | 70,000 psi (E70xx), 60,000 psi (E60xx) | Slag inclusions, bad restarts, damp low-hydrogen rods |
| MIG (GMAW) | ER70S-6 solid wire | 70 ksi | Cold lap from short circuit transfer on thick plate |
| Flux core (FCAW) | E71T-1 gas-shielded wire | 70 ksi | Trapped slag, porosity from poor technique |
| TIG (GTAW) | ER70S-2 or ER70S-6 rod | 70 ksi | Lack of fusion when amperage is too low for the thickness |
These ratings are AWS minimums. A data sheet can list a higher typical value, but Hobart advises designing to the AWS classification, not the higher number.
What Makes a Weld Strong
Weld strength comes from 5 things working together. Get one wrong and a 70 ksi filler can still crack or tear at a fraction of its rating.
Filler Metal Strength
The first 2 digits of a stick electrode give its minimum tensile strength. Lincoln Electric explains that an E6010 is a 60,000 psi electrode, so an E7018 is a 70,000 psi electrode. The other welding rod numbers tell you the position and coating type.
Matching does not mean an exact match. Hobart’s example: A36 steel has a 36 ksi minimum yield, and you can weld it with a 70 ksi filler that has a 58 ksi minimum yield.
The Canadian Welding Bureau (CWB) says the usual goal is a filler equal to or stronger than the base metal. When you join 2 different steels, match the filler to the weaker of the 2. CWB and Hobart both say overmatching is usually discouraged.
Penetration and Fusion
A weld only carries load where it has fused into both pieces. Cold lap, where the bead sits on top of the plate, can look fine and still pull off under stress.
Hobart notes that a short-circuit solid wire weld on 1/2 inch material may be weaker than a spray transfer weld on the same plate, because the heat input does not suit the thickness. The choice of short circuit vs spray transfer matters most on thick plate.
Heat Input
Heat input changes the weld metal itself. Hobart explains that low heat input can raise strength but lower ductility, and very high heat input acts much like a high CO2 gas mix.
So the hottest weld is rarely the strongest one. Use the amperage and travel speed your filler maker lists for the thickness.
Shielding Gas
Gas changes the strength of the same wire. Hobart reports that an E71T-1 flux-cored wire meets the 70 ksi AWS minimum but tests at about 84 ksi with 100% CO2 and 90 ksi with 75% argon / 25% CO2.
More argon raises tensile and yield strength but cuts ductility. More CO2 raises ductility but lowers tensile and yield strength. For parts that flex or take impact, a little ductility is worth more than a few extra ksi.
Joint Design and Weld Size
A perfect bead that is too small for the load will still fail. The joint type, the throat size and the length of the weld set how much force it can carry.
For fillet joints, fillet weld strength depends on throat size, length and filler rating. For load-bearing steel, an engineer or the code your job follows sets the weld size.
Clean Metal and Welder Skill
Rust, paint, oil and mill scale cause porosity and inclusions. Grind to bright metal at the joint, keep low-hydrogen rods dry, and hold a steady angle and arc length.
A skilled welder with a stick machine will beat a beginner with a TIG torch on most structural joints. Practice and test welds count more than the machine.
Strongest Welding Process for Each Job
TIG Welding
TIG welding gives you the most control over heat and filler. That control makes clean, low-spatter welds on thin steel, stainless, aluminum and chromoly tube, where small defects matter most.
TIG is slow on thick plate. For heavy sections, the strength edge usually goes to a process with more deposition and deeper penetration.
MIG Welding
MIG welding with ER70S-6 wire and spray transfer makes strong, deep welds on thick steel in the flat and horizontal positions. Short circuit transfer suits thin metal but needs care on thick plate to avoid cold lap.
Stick Welding
For stick welding, E7018 low-hydrogen rods are a common choice for structural steel, trailers and field repairs. Stick also handles wind and less-than-clean metal better than gas-shielded MIG or TIG.
Flux Core Welding
With flux core welding, you put down a lot of metal fast and get good penetration on thick steel. Self-shielded wire works outdoors without a gas bottle, which makes it popular for farm and field repairs.
Friction Stir and Other Industrial Processes
TWI, the UK welding institute that developed friction stir welding, says the process joins metal in the solid phase, below its melting point. TWI reports excellent fatigue, tensile and bend test results and no porosity, and it can join 2XXX and 7XXX aluminum alloys that are hard to fusion weld.
Electron beam and laser welding make deep, narrow welds with a small heat-affected zone. All 3 need dedicated machines, so they belong in aerospace, auto and rail plants, not a garage.
How to Make Any Weld Stronger
- Pick a filler class that meets or beats the strength the part needs, and match the weaker base metal on mixed joints.
- Bevel thick plate so the weld can reach the root.
- Clean the joint to bright metal on both sides.
- Set amperage, voltage and wire speed from the filler maker’s chart for your thickness.
- Keep low-hydrogen rods and flux core wire dry.
- Run test coupons and break them in a vise before you weld the real part.
Safety note: Hitches, lifting gear, structural beams and pressure parts need a qualified procedure and often a certified welder. Wear a helmet with the right shade, dry gloves and FR clothing, and ventilate to clear welding fumes.
Frequently Asked Questions
Is TIG welding stronger than MIG welding?
TIG is not stronger by default. With the same 70 ksi filler class, both processes have the same minimum tensile rating. TIG gives more control on thin or critical parts, and spray transfer MIG often fuses thick steel better. The stronger weld is the one with full fusion and the right heat input.
Is stick welding stronger than MIG?
A 70 ksi stick rod like E7018 and a 70 ksi MIG wire like ER70S-6 carry the same AWS minimum tensile rating. Stick can beat short circuit MIG on thick, dirty or outdoor work, where MIG risks cold lap and gas loss. Technique decides the result.
Can a weld be stronger than the base metal?
Yes. A 70 ksi filler on A36 steel, which has a 36 ksi minimum yield, gives weld metal stronger than the plate. That is why a sound weld on mild steel often tears in the plate next to the bead during a break test, not through the weld.
What is the strongest welding rod for mild steel?
Among common rods for mild steel, E7018 carries a 70,000 psi minimum tensile rating, higher than 60,000 psi E6010, E6011 and E6013 rods. Higher classes such as E8018 exist for high-strength steel. For ordinary mild steel, CWB and Hobart say overmatching is usually discouraged.
Is flux core welding as strong as MIG?
Yes, when the wire class matches. An E71T-1 flux-cored wire meets the same 70 ksi AWS minimum as ER70S-6 solid wire, and Hobart reports higher typical values with gas. Flux core often penetrates thick steel better, but trapped slag or porosity will weaken it.
Final Words
The strongest type of welding for your project is the process you can run with full fusion, clean metal and a filler rated for the load. On mild steel, TIG, MIG, stick and flux core all reach the same 70 ksi class.
Choose TIG for thin and critical parts, spray MIG or flux core for thick steel in the shop, and E7018 stick for structural and field work. Then run a test piece and break it before you trust the real weld.
