Which of the following statement(s) is/are true regarding butt welding?
1. Flash butt welding is a combination of resistance, arc and pressure welding
2. Upset butt welding is used for welding rods
3. Percussion Welding is a self timing spot welding method
4. Aluminium alloys are flash welded
1
1, 2, and 3
2
Only 2 and 3
3
1, 2, 3, and 4
4
Only 1 and 4