All I know about welding is it is a technique in which electrode is connected to one terminal and the gripper connected to workpiece is in connection with the other terminal. As current passes and when the electrode is touched to the workpiece,an arc is generated which melts electrode and helps in the formation of a joint. As the circuit is completed with a conductor in-between,doesn't it result in short circuit?
No, this is not classed as a "short-circuit". This is a circuit with a designed current flow - ie a 60 to 150A range is common...
A "short-circuit" is a circuit where the current flow is not following the designed current path ie it is taking a "shorter" route to ground.