How You Could Weld Dissimilar Metals

Mar. 17, 2023

Austenitic stainless steels such as grade 304 stainless or grade 316 stainless can be welded to plain carbon steel using MIG and TIG welding. When welding stainless steel to a dissimilar metal such as plain carbon steel, weld processes such as MIG welding that use filler material are preferred.

Resistance welding of stainless and carbon steel isn't typically done, as the differences in electrical conductivity between the two metals make reaching the right weld temperature extremely difficult. When resistance welding is used, the carbon steel is usually preheated since it's more electrically conductive and doesn't heat up as fast as stainless steel.

Stainless Steel Welding Wire

Stainless Steel Welding Wire

What Type of Welding is Used for Stainless Steel?

When determining what form of welding is best for your custom wire basket, the answer depends on what type of metal is being used. If your custom basket is made from stainless steel, then there are certain methods that are superior compared to others for stainless steel welding.

The properties of stainless steel have to be considered before choosing a weld. For example, Marlin Steel makes most of its custom wire baskets from grade 304 or 316 stainless steel, they are corrosive-resistant and have a high tensile strength. Chrome-nickel stainless steel alloys have a high electrical resistance and cool off fast. Since stainless steel alloys bond and solidify quickly with minimal distortion, resistance welding is the best welding technique for stainless steel.

Using a resistance weld for stainless steel welding is an easy, smoother process when compared to other metals. Due to its high resistance to current flow, heat at the weld joint is generated easier and quicker than mild steel.


How to Weld Stainless Steel to Other Metals?   

When welding stainless steel to other metals, other types of welding should be considered than resistance welding. For instance, MIG and TIG welding are preferred types of welding stainless steel to carbon steel together. When combining dissimilar metals together, such as welding stainless steel to carbon steel, a filler material is needed to bind the two metals. In MIG welding, a continuously-fed electrode wire melts into the weld, enabling two dissimilar metals to be joined without heating them to their melting points.

When welding stainless steel with MIG processes, the team at Marlin Steel programs a MIG welding robot to complete the weld. A filler must be used since the melting points of the two dissimilar metals may be very different. For instance, if one of the metals is overheated to reach the melting point of the other one, stress cracks and microfractures may result. Welding two dissimilar metals is possible, but a very difficult process with plenty of complications.


Reasons You Want to Avoid Welding Stainless Steel to Carbon Steel

Difficulty. Combining dissimilar metals together, such as welding stainless steel to carbon steel, adds extra challenges to the process. This translates into increased labor, rejection/error rates, and costs.

ㆍHot Cracking of the Stainless Steel. Because it is more electrically-resistant than carbon steel, welding stainless steel with resistance welding heats up the metal much faster than with carbon steel. While waiting for the carbon steel to reach weld temperature, the stainless can overheat and become riddled with hot cracks. Using filler-based welding or preheating the plain steel can ameliorate this, but these methods aren't perfect.

ㆍThermal Expansion in High Temperature Service Conditions. Another problem with using dissimilar metals in a welded wire form is that thermal expansion from heat will affect each metal differently. This difference in expansion rates between the two metals can cause extra fatigue to the welded joint—reducing the wire form's structural integrity and useful life.

ㆍIncreased Bimetallic Corrosion. One of the reasons you generally want to use stainless steel is because of its strong corrosion resistance. An uncovered weld of plain and stainless steel that is exposed to extreme corrosive conditions, such as immersion in saltwater, could cause corrosion. This is because the intermingling of plain steel particles with the stainless alloy compromises the protective oxide layer of the stainless, allowing rust to form.

ㆍReduced Weld Strength. Another problem with joining dissimilar metals is that it can lead to weaker welds—even with filler-based welding methods. The differences in weld temperatures and operational tolerances alone can easily compromise the strength of the welded joint.

To boil it down, welding dissimilar metals together is difficult to do right, and often produces inferior results to using metal alloys that are similar or the same.

If you have a question about stainless steel welding, or need welding wires, be sure to contact us!