How can the welder control the width of the weld bead?

The correct answer focuses on the welder's ability to control the width of the weld bead through several key factors: arc length, travel speed, and the angle of the torch.

Adjusting the arc length influences the heat input and penetration into the base material. A shorter arc length typically results in a narrower bead due to a more concentrated heat source, while a longer arc length can lead to a wider bead because of the more diffused heating.

Travel speed is critical as it determines how quickly the torch moves along the joint. A slower travel speed allows for more heat accumulation in a particular area, potentially widening the bead, whereas a faster speed narrows the bead by reducing the heat input.

The angle of the torch affects how the heat is directed onto the base material. An altered torch angle can spread the heat more aggressively in either the horizontal or vertical direction, thus impacting the weld bead's width.

While other choices appear to relate to factors in welding, they don't directly control the bead width as effectively as the arc length, travel speed, and torch angle adjustments. Gas flow rate, filler material selection, and workpiece temperature indeed have important roles in the welding process, but they primarily influence aspects such as arc stability, filler metallurgical properties