How should the filler rod behave as it enters the puddle?

• A. Melt in a jagged fashion to match the warp
• B. Lay on the surface and push around
• C. Melt away from the puddle
• D. Melt smoothly into the puddle, not clump

Answer: (C)

In TIG welding, filler metal should be drawn into the molten puddle and fuse with the base metal, forming a smooth, uniform bead. You bring the filler into the leading edge of the puddle with a slight angle and let the heat of the pool melt the tip as it enters. Feed steadily so the molten filler flows into the pool rather than being left on the surface or pushed around. The goal is a seamless blend where the new metal is incorporated into the weld, not a lump or a surface layer.

If the filler melts on the surface and is pushed around, it won’t fuse properly and can create an uneven bead or contamination. If it melts away from the puddle, there’s little or no fusion and the joint won’t fill correctly. A jagged melt indicates uneven heat input and a rough bead, which can lead to defects.