Stainless Steel Welding Tips: Best Practices for 304 and 316
Both 304 and 316 stainless steel offer excellent weldability, but they require different approaches. 304 (18Cr-8Ni) is the most commonly welded stainless grade. 316 (16Cr-10Ni-2Mo) contains molybdenum for enhanced corrosion resistance but requires slightly more careful heat input control to prevent sensitization.
Understanding 304 vs 316 Weldability
Both 304 and 316 stainless steel offer excellent weldability, but they require different approaches. 304 (18Cr-8Ni) is the most commonly welded stainless grade. 316 (16Cr-10Ni-2Mo) contains molybdenum for enhanced corrosion resistance but requires slightly more careful heat input control to prevent sensitization.
Filler Metal Selection Guide
For 304 base metal: use ER308L or E308L electrodes. The ‘L’ designation means low carbon (<0.03%), which prevents carbide precipitation at grain boundaries. For 316 base metal: use ER316L or E316L. When welding dissimilar stainless steels, use the higher-alloy filler (e.g., 304 to 316 → use 316L filler).
TIG Welding (GTAW) Parameters
TIG welding produces the highest quality stainless welds. Key parameters: amperage 60-180A depending on thickness, argon shielding gas at 10-15 L/min, thoriated or ceriated tungsten electrodes. Maintain a short arc length (1-2mm tungsten extension). For material <3mm, use DCEN polarity with no filler for autogenous welds.
MIG Welding (GMAW) Parameters
MIG welding is faster for thicker sections (>3mm). Use spray transfer mode for material >3mm and short-circuit transfer for thin gauge. Shielding gas: 98% Ar + 2% CO₂ for general purpose, or 90% He + 7.5% Ar + 2.5% CO₂ for higher travel speeds. Wire diameter: 0.8mm for thin sheets, 1.0-1.2mm for plate.
Avoiding Common Weld Defects
Common stainless welding defects include: sensitization (carbide precipitation at 450-850°C), hot cracking (from high sulfur content), distortion (from high thermal expansion — 50% more than carbon steel), and sugar beading on root passes (from insufficient back purging). Prevention: control interpass temperature below 150°C, use low-heat-input techniques, and always back purge with argon for root passes.
Post-Weld Treatment & Quality
After welding, remove the heat tint (discoloration) using pickling paste or electropolishing to restore corrosion resistance. Passivation with citric or nitric acid removes free iron from the weld zone. For critical applications, perform dye penetrant testing (DPT) to verify weld integrity. CoreMetal supplies pre-welded and welded stainless assemblies — contact our team for custom fabrication support.
About Xi’an Coremetal Steel Co., Ltd.
CoreMetal is a leading Chinese steel supplier specializing in carbon steel, stainless steel, galvanized products, aluminum, and specialty alloys. With ISO 9001 certification and export experience to 60+ countries, we provide competitive pricing and reliable delivery for projects of all sizes. Contact Tracy at tracy@coremetalsteel.com or +86 18291910632 for inquiries.