What is the effect of an increase in wire feed speed?

An increase in wire feed speed in MIG welding contributes to a wider and deeper penetration of the weld. This is due to the higher amount of filler material supplied into the weld pool, which allows for more molten metal to be deposited during the welding process. When the wire feed speed is elevated, the arc has more metal to fuse, leading to better penetration and a more robust weld joint.

Moreover, the interaction between the increased feed speed and the heat applied by the welding arc can enhance the fusion of the base metals, resulting in both a deeper and wider bead when compared to lower wire feed speeds. This makes the weld more suitable for applications requiring strength and durability.

The other options pertain to effects that do not occur with an increase in wire feed speed, such as a decrease in penetration or having no effect at all. Therefore, the choice that indicates an increase in both depth and width of weld penetration accurately captures the relationship between wire feed speed and weld characteristics.