Question 1
Electron beam welding is carried in?
A. Inert atmosphere
B. Partially filled chamber
C. Vacuum
D. Partially vacuum
View Answer
Answer: Option C
Explanation:
In electron beam welding process, electrons are emitted from the heated filament called electrode. This is done under vacuum conditions to prevent dissipation of the electron beam.
Question 2
In Thermit welding the heat generated is due to the mixing of?
A. Aluminum and copper
B. Aluminum and iron
C. Aluminum oxide and iron
D. Aluminum and iron oxide
View Answer
Answer: Option D
Explanation:
Thermite welding is a welding process in which the workpiece is joined with the help of molten metal by means of an exothermic reaction. Thermite mixture consists of a metal oxide (usually iron oxide) and aluminum powder. The major application of thermite welding is to weld railway tracks. It is also used to weld heavy machinery.
Question 3
In which welding process pressure is applied by detonating a layer of explosive?
A. Percussion welding
B. Explosion welding
C. Diffusion welding
D. Thermit welding
View Answer
Answer: Option B
Explanation:
In explosion welding, a compression force created by detonation of explosives is used to join overlapping metal sheets. The joining parts are arranged toward each other at an angle of 1-15°, depending on the material and method, and are prepared with a layer of explosive on the top.
Question 4
In which welding process the electric energy required for welding is stored in the capacitor?
A. Percussion welding
B. Explosion welding
C. Diffusion welding
D. Thermit welding
View Answer
Answer: Option A
Explanation:
In percussion welding, two pieces are welded by a high intensity short duration arc followed by very rapid or percussive impacting of the workpieces. There are three different methods of arc initiation in percussion welding viz., low voltage with drawn arc, high voltage breakdown, and ionising by a fusing tip. With each method, the energy source is a bank of capacitors which is charged by a variable voltage transformer cum rectifier unit.
Question 5
In which welding the strength of the weld results due to diffusion and plastic deformation of the flying surface?
A. Diffusion welding
B. Thermit welding
C. Laser beam welding
D. Ultrasonic welding
View Answer
Answer: Option A
Explanation:
In diffusion welding, the bond strength is achieved by pressure, temperature, time of contact, and cleanness of the surfaces. The strength of the bond is primarily due to diffusion rather than any plastic deformation.
Question 6
In which welding the surfaces of two components are subjected to static normal force and oscillating shear stress?
A. Diffusion welding
B. Thermit welding
C. Laser beam welding
D. Ultrasonic welding
View Answer
Answer: Option D
Explanation:
In ultrasonic welding (USW), the faying surfaces of the two members are subjected to a static normal force and oscillating shearing (tangential) stresses. The shearing stresses are applied by the tip of a transducer similar to that used for ultrasonic machining.
Question 7
Which of the following statements is not true?
A. Brazing occurs at a temperature above 450°C
B. Soldering occurs at a temperature below 450°C
C. Epoxy resins are used to join metals, ceramics etc
D. Epoxy resins are not used to join metals, ceramics etc
View Answer
Answer: Option D
Explanation:
The excellent adhesive properties of epoxy resins are due to the attractive forces between the epoxy resin and the surface of the substrate. Typical epoxy resins have pendant hydroxyl (-OH) groups along their chain which can form bonds or strong polar attractions to oxide or hydroxyl surfaces. Most inorganic surface, i.e., metals, minerals, glasses, ceramics, etc. have polarity so they have high surface energy. Organic polymer surfaces are generally less polar (more covalent) thus lower surface energy.
Question 8
Which of the following welding is also known as arc and gas welding?
A. Electro slag welding
B. Atomic hydrogen welding
C. Laser beam welding
D. Ultrasonic welding
View Answer
Answer: Option B
Explanation:
Atomic hydrogen welding, also known as AHW, is an arc welding technique that uses an arc which is located between two tungsten electrodes and a hydrogen shielding gas.
Question 9
Which of the following welding is used for welding vertical section in one pass?
A. Electro slag welding
B. Atomic hydrogen welding
C. Laser beam welding
D. Electro gas welding
View Answer
Answer: Option D
Explanation:
Electro gas welding (EGW) is an vertical positioned arc welding process, is used for welding the edges of sections vertically and in one pass with the pieces placed edge to edge (butt joint).
Question 10
Which of the following welding process the weld joint is obtained by means of filler material and not by melting?
A. Diffusion welding
B. Thermit welding
C. Electroslag welding
D. Brazing
View Answer
Answer: Option D
Explanation:
A brazed joint is made in a completely different manner from welded joint. The big difference is in temperature-brazing does not melt the base metals. This means that brazing temperatures are invariably lower than the melting points of the base metals. It joins base metals by creating a metallurgical bond between the filler metal and the surfaces of the two metals being joined. The principle by which the filler metal is drawn through the joint to create this bond is capillary action.