Mastering Aluminum TIG Welding Techniques

Aluminum TIG welding is where many welders hit their first real challenge. The metal behaves differently than steel, and it requires a different approach. But once you understand the fundamentals, you can create beautiful, strong aluminum welds. Why Aluminum is Different Aluminum has several properties that make it challenging to weld: High thermal conductivity: Heat spreads quickly, making it hard to maintain a weld pool Oxide layer: Aluminum oxide melts at a much higher temperature than the base metal No color change: Unlike steel, aluminum doesn't change color when it's hot High expansion rate: Aluminum expands and contracts more than steel Equipment Setup for Aluminum AC Current is Essential Aluminum requires AC (alternating current) to break through the oxide layer. DC won't work for aluminum TIG welding. Settings to start with: AC frequency: 120-150 Hz AC balance: 70-80% electrode negative Amperage: 1 amp per thousandth of inch thickness Gas Flow Aluminum needs more gas flow than steel. I typically run 20-25 CFH for aluminum work. Pro Tip Use a gas lens kit for aluminum. The better gas coverage helps prevent contamination and produces cleaner welds. Material Preparation Proper preparation is crucial for aluminum welding success. Cleaning Aluminum must be absolutely clean. Any contamination will cause problems. Remove any oil or grease with acetone Use a stainless steel wire brush (dedicated to aluminum only) Clean both sides of the joint Wipe with acetone again Joint Preparation Aluminum joints need to be properly prepared: Square edges for butt joints Proper gap (usually 1/16" to 1/8") Clean, burr-free edges Welding Technique Heat Control Aluminum requires more heat than steel, but you need to control it carefully. Key points: Start with higher amperage than you think you need Use your foot pedal to control heat input Keep the arc length short and consistent Travel Speed Aluminum requires faster travel speed than steel. If you go too slow, you'll burn through or create excessive heat input. Speed Tip Practice your travel speed on scrap pieces first. Aluminum will tell you immediately if you're going too slow by burning through. Filler Rod Technique Aluminum filler rod technique is different from steel: Keep the filler rod close to the arc Dip the rod into the leading edge of the puddle Use a dabbing motion, not a continuous feed Keep the rod covered with gas Common Problems and Solutions Porosity Porosity in aluminum is usually caused by: Insufficient gas coverage Contaminated material Dirty filler rod Solution: Increase gas flow, clean everything thoroughly, and use clean filler rod. Burn Through Burn through happens when you're too slow or have too much heat. Solution: Increase travel speed or reduce amperage. Use a backing strip for thin material. Lack of Fusion Lack of fusion occurs when you don't get the base metal hot enough. Solution: Increase amperage and slow down slightly. Make sure you're getting good penetration. Advanced Techniques Pulse Welding Pulse welding can help control heat input and reduce distortion: Peak current: 200-300 amps Background current: 50-100 amps Pulse frequency: 1-3 Hz Backing Strips For thin aluminum, use a backing strip to prevent burn through and provide support. Practice Makes Perfect Aluminum TIG welding takes practice. Start with simple joints and work your way up to more complex projects. Don't get discouraged - even experienced welders struggle with aluminum at first. Testing Your Welds Always test your aluminum welds: Visual inspection for cracks and porosity Bend tests for ductility Destructive testing for critical applications Next Steps Mastering aluminum TIG welding opens up a world of possibilities. From automotive work to aerospace applications, aluminum is everywhere. For more advanced aluminum techniques, including specialized applications and troubleshooting, check out my comprehensive guide in "TIG Welding Secrets."