A shielded metal arc welding operation takes place on a steel workpiece (with a steel electrode) with a 20 V power supply. If a weld with a triangular cross-section with a 10 mm leg length is to be produced, estimate the current needed for a welding speed of 10 mm/s. Use an efficiency of 80% and specific energy as 10.3 J/mm2
Heat input in arc welding
H = u(volume) = uAl
where u is specified energy
∴ welding speed,
Match the List-I (Welding processes) with List-II (Description):
A. Plasma arc welding
B. MIG welding
C. TIG welding
D. Electroslag welding
1. Arc is produced between a non-consumable electrode and the workpiece.
2. Is very much useful for joining thick materials?
3. Gives high heat concentration resulting in higher welding speeds.
4. Uses consumable electrodes.
A B C D
(a) 4 3 1 2
(b) 3 2 1 4
(c) 3 4 1 2
(d) 2 4 1 3
Match the List-I (Filler rod materials) with List-ll (Joining processes):
A. Mild steel
D. Lead and tin alloy
1. MIG welding
4. Thermit welding
5. Braze welding
A B C D
(a) 1 5 3 2
(b) 4 3 2 5
(c) 4 3 5 2
(d) 1 3 5 4
Electron beam welding can be carried out in
Match the List-I (Welding processes) with List-II (Features):
A. Ultrasonic welding
B. Electron beam welding
C. Plasma arc welding
D. Stud welding
1. Gas heated to ionized condition for conduction of electric current
2. High frequency and high intensity vibrations
3. Requires vacuum
4. Exothermic chemical reaction
5. Ceramic ferrule Codes:
A B C D
(a) 1 2 4 5
(b) 4 3 1 2
(c) 2 1 4 3
(d) 2 3 1 5
The major difficulty during welding of aluminium is due to its
Consider the following statements:
1. The electrode is non consumable.
2. Both DC and AC power supplies can be used.
3. Fluxes are required for thinner sections.
Q. Which of the above statements is/are correct for TIG welding?
Which one of the following is not a fusion welding process?
Gas welding, arc welding and resistance welding are the fusion welding process while brazing is allied process in which parent metal is not heated up to molten state.
Which of the following welding techniques uses a non-consumable electrode?
TIG welding uses tungsten electrode which is non-consumable.
In arc welding arc is created between the electrode and work by
Preheating of work piece is essential in welding
Preheating is often employed when welding cast iron, high carbon steel or alloy steel since preheating slows down the cooling rate of that area of parent metal close to the weld itself and the weld itself and thereby prevents the formation of martensite which accounts for hardness across the weld. The chance of cracking in the heat- affected zone due to unequal contraction during cooling is also minimized by preheating.
Consider the following statements:
MIG welding process uses
1. Consumable electrode
2. Nonconsumable electrode
3. D.C. power supply
4. A.C. power supply
Q. Which of these statement are correct?
Metal inert gas arc welding or more appropriately called as gas metal arc welding utilizes a consumable electrode. Normally DC arc welding machines are used for MIG with electrode positive.
Grey cast iron is usually welded by
Arc blow is more common in
The phenomenon of weld decay occurs in
High speed electron beam of electron beam welding is focused on the weld spot using
Electromagnetic focusing lens are used to creat magnetic field and due to this electron converge into beam.
Which one of the following welding processes consists of minimum heat affected zone
Minimum heat affected zone is obtained by laser beam walding and then electron beam welding.
Following gases are used in TIG welding
The shielding gases most commonly used are argon, helium, carbon dioxide and mixture of them.
In arc welding process the intense heat is developed between the work and the electrode largely due to
Lap joints are employed on plates having thickness
Seam welding is a
In seam welding electrodes used in the form ol rollers or wheels, and leak proof joint is obtained bv this.
Which one of the following is not an electric resistance method of welding
Electroslag welding is a type of arc welding.
The maximum heat in resistance welding is at the
Since the resistance is maximum at the interference of the two sheets being joined hence maximum heat will generate at the same place.
Preheating before welding is done to
In shielded arc welding
Shielded metal arc welding is most extensively used manual welding process which is done with coated electrode. The coating is known as flux.
In which of the following welding techniques in vacuum environment required
In electron beam welding, vacuum is required in order to conserve the kinetic energy of electron beam before hitting the workpiece.
Pinch effect in welding is the result of
Since electrode can be considered as large number of parallel conductors and when current flows in the same direction an attractive force will develope this is known as pinch force. Since this is a electromagnetic force hence it is also called electromagnetic pinch force.
Projection welding is
The temperature of plasma torch is of the order is
The temperature of plasma torch is around 33000°C.
Oxyacetylene flame cuts metal by its