Which polarity is best used for TIG welding stainless steel?

When TIG (Tungsten Inert Gas) welding stainless steel, DCEN (Direct Current Electrode Negative) is the preferred polarity. This is because DCEN offers several advantages when working with stainless steel.

Using DCEN means that the majority of the welding current flows through the workpiece rather than the tungsten electrode. This results in a deeper penetration and a more focused arc, which is crucial when welding stainless steel, allowing for strong, quality welds with less distortion.

Furthermore, this method minimizes the heat affected zone, which helps in maintaining the metal's structural integrity and prevents excessive warping. The combination of these factors ensures that the weld is clean and that the stainless steel retains its properties, such as corrosion resistance.

While AC (Alternating Current) is common for welding materials like aluminum and can be used in specific scenarios for stainless steel, it is not as effective as DCEN for the majority of stainless steel welding tasks. DCEP (Direct Current Electrode Positive) is also not suitable in this case, as it tends to lead to a wider heat-affected zone and less penetration, which can compromise the quality of the weld. Thus, DCEN stands out as the best choice for TIG welding stainless steel.