Low current leads to which of the following effects?

Low current leads to which of the following effects?

• A. Inadequate penetration; unstable arc; high narrow bead; lack of fusion
• B. Melt through
• C. Overheating of base metal
• D. No change to bead

Answer: (A)

Low current means less heat input into the weld zone. With too little heat, the metal doesn’t melt enough to fuse properly with the base metal and filler, so penetration becomes shallow and there can be lack of fusion at the joint. The arc also tends to be unstable because there isn’t enough energy to sustain a steady, smooth arc, leading to an uneven, erratic bead. The result is a bead that is narrow and poorly fused, sometimes with a higher profile due to limited lateral deposition. Melt-through and base-metal overheating require excessive heat, not too little, and a bead that doesn’t change with current would ignore the clear effect of reduced heat input.

Low current means less heat input into the weld zone. With too little heat, the metal doesn’t melt enough to fuse properly with the base metal and filler, so penetration becomes shallow and there can be lack of fusion at the joint. The arc also tends to be unstable because there isn’t enough energy to sustain a steady, smooth arc, leading to an uneven, erratic bead. The result is a bead that is narrow and poorly fused, sometimes with a higher profile due to limited lateral deposition. Melt-through and base-metal overheating require excessive heat, not too little, and a bead that doesn’t change with current would ignore the clear effect of reduced heat input.