In the ____ process, the high frequency vibratory energy is used

SOLUTION

Concept:

Ultrasonic welding:

• Ultrasonic welding, the most widely used welding method, uses ultrasonic energy at high frequencies (20 - 40 kHz), that are beyond the range of human hearing, to produce low amplitude (1 - 25 μm) mechanical vibrations.
• The vibrations generate heat at the joint interface of the parts being welded, resulting in melting of the thermoplastic materials and weld formation after cooling.
• It is the fastest known welding technique, with weld times of less than one second.
• Ultrasonic welding is used for both soft and rigid thermoplastics and for thermoplastic composites. 

Thermit welding:

• In this process the heat required for melting and joining of plates is due to the exothermic chemical reaction of the thermit mixture, therefore it is called as chemical welding operation.

          Fe₂O₃ + 2Al ⇒ 2Fe + Al₂O₃ + Heat

• Due to the thermit chemical mixture reaction, 3 products are produced,
  • Iron - Used as filler rod
  • Al₂O₃ - Used as a slag
  • Heat - Used for the melting of the parent material.

Submerged Arc Welding(SAW):

• Submerged arc welding is an arc welding process in which heat is generated by an arc which is produced between bare consumable electrode wire and the work-piece.
• Due to the usage of the large quantity of flux powder, the arc produced between the tip of the electrode and workpiece is completely submerged inside the flux powder hence it is called submerged arc welding.
• This method can be used for the joining of low and high melting point highly reactive metals.

Gas Tungsten Arc Welding (GTAW):

• It uses non - consumable electrode which is made by using tungsten as a material.
• Inert gas supplied as a shielding gas through a cover provided around the electrode.
• Due to continuous welding operation, the temperature of the tip of the electrodes becomes high and at high temperature the atoms of the tungsten will get diffused, entering into the weld pool and contaminating the weld bead. i.e. brittleness of weld bead is increasing, to avoid this coolant supplied around the electrode.