From many welding materials in the industry, welding Hard Steel was easy if practiced well enough, but the final welded product of steel came with its own set of challenges, corrosion being the primary reason.
With developments in the metallurgical industry, low alloy steel was brought into the picture. Stainless Steel (SS), an alloy discovered in the 1800s was a revolutionary alloy with many uses, primarily used in industrial equipment when long-lasting durability of the equipment was a priority that could be easily cleaned and the performance has been improved in many new ways.
Stainless Steel is far more corrosion-resistant than standard carbon steel, popularly known for its enhanced durability, corrosion resistance & high-temperature oxidation resistance.
Coming along in various material types, the special properties of stainless steel were brought out by the simple addition of alloying elements like nickel and chromium to steel.
The formula is that more than 10% chromium is required to produce a stainless iron. Stainless steel has 4 grades which are further classified depending on the welding requirements, welding characteristics, microstructure (the key influencing factor in how strong the steel is going to be) and material strength.
Austenitic Stainless Steel: Single-phase, which is very commonly used to create stainless steel welding rods.
Ferritic Stainless Steel: Single phase, commonly used as they are cheap to manufacture.
Martensitic Stainless Steel: Used for high wear and tear hard facing applications.
Austenitic-ferritic (duplex) Stainless Steel: Double-phase that contains both ferrite and austenite in the microstructure.
With such effective properties, why is it so hard to weld Stainless Steel?
What makes welding a bit more challenging and tedious, especially for an expert welder is because Stainless Steel warps under high temperatures and distort the whole cooling process due to poor thermal conductivity.
The welding result does not look flawless as it displays every blemish and scratch mark that’s left behind. Correcting welding mistakes is also a bit of a challenge so precautions are needed to be taken or else it would deform very easily.
Approaches we can use in welding Stainless Steel.
The not-so-simple answer is, it depends on what result you’re trying to achieve.
Stainless Steel can be welded with shielded metal arc welding (SMAW), gas tungsten arc welding (TIG) and MIG welding, and each of these processes will yield a slightly different result.
To find the best welding process for your project, consider the following factors: the welder’s skill level, the aesthetics of the final piece including bead appearance, the thickness of the metal plus the costs and timing factors of the project. If artistry is paramount, then the finesse of TIG welding could be a good fit, but if speed and efficiency are a priority, then MIG welding may be a better process.
To simply answer your query, if you're looking for a more affordable weld, spot welding might be the best option for the job. But if the material we’re working with is thin, then TIG or gas tungsten arc welding might be the better choice.