GATE Questions & Answers of Principles of Welding, Brazing, Soldering and Adhesive Bonding

What is the Weightage of Principles of Welding, Brazing, Soldering and Adhesive Bonding in GATE Exam?

Total 24 Questions have been asked from Principles of Welding, Brazing, Soldering and Adhesive Bonding topic of Casting, Forming and Joining Processes subject in previous GATE papers. Average marks 1.50.

The type of weld represented by the shaded region in the figure is

 

A welding operation is being performed with voltage = 30 V and current = 100 A. The cross-sectional area of the weld bead is 20 mm2 . The work-piece and filler are of titanium for which the specific energy of melting is 14 J/mm3 . Assuming a thermal efficiency of the welding process 70%, the welding speed (in mm/s) is __________ (correct to two decimal places).

In an arc welding process, welding speed is doubled. Assuming all other process parameters to be constant, the cross sectional area of the weld bead will

Under optimal conditions of the process the temperatures experienced by a copper work piece in fusion welding, brazing and soldering are such that

The welding process which uses a blanket of fusible granular flux is

The voltage-length characteristic of a direct current arc in an arc welding process is $ V= $ ( 100 + 40 ), where $ l $ is the length of the arc in mm and $ V $ is arc voltage in volts. During a welding operation, the arc length varies between 1 and 2 mm the welding current is in the range 200-250 A. Assuming a linear power source, the short circuit current is _________ A.

Spot welding of two steel sheets each 2 mm thick is carried out successfully by passing 4 kA of current for 0.2 seconds through the electrodes. The resulting weld nugget formed between the sheets is 5 mm in diameter. Assuming cylindrical shape for the nugget, the thickness of the nugget is________mm.
 
  Latent heat of fusion for steel   1400 kJ/kg
  Effective resistance of the weld joint   200 μΩ
  Density of steel   8000 kg/m3

 

In a linear arc welding process, the heat input per unit length is inversely proportional to

A DC welding power source has a linear voltage-current (V-I) characteristic with open circuit voltage of 80 V and a short circuit current of 300 A. For maximum arc power , the current (in Amperes) should be set as_______.

During a TIG welding process, the arc current and arc voltage were 50 A and 60 V, respectively, when the welding speed was 150 mm/min. In another process, the TIG welding is carried out at a welding speed of 120 mm/min at the same arc welding voltage and heat input to the material so that weld quality remains the same. The welding current (in A) for this process is

Which two of the following joining processes are autogeneous?

(i) Diffusion welding
(ii) Electroslag welding
(iii) Tungsten inert gas welding
(iv) Friction weding

The major difficulty during welding of aluminium is due to its

In solid-state welding, the contamination layers between the surfaces to be welded are removed by

For spot welding of two steel sheets (base metal) each of 3 mm thickness, welding current of 10000 A is applied for 0.2 s. The heat dissipated to the base metal is 1000 J. Assuming that the heat required for melting 1 mm3 volume of steel is 20 J and interfacial contact resistance between sheets is 0.0002 Ω, the volume (in mm3) of weld nugget is __

Within the Heat Affected Zone (HAZ) in a fusion welding process, the work material undergoes

A butt weld joint is developed on steel plates having yield and ultimate tensile strength of 500 MPa and 700 MPa, respectively. The thickness of the plates is 8 mm and width is 20 mm. Improper selection of welding parameters caused an undercut of 3 mm depth along the weld. The maximum transverse tensile load (in kN) carrying capacity of the developed weld joint is _______

Match the CORRECT pairs.

Processes Characteristics / Applications
P. Friction Welding 1. Non-consumable electrode
Q. Gas Metal Arc Welding 2. Joining of thick plates
R. Tungsten Inert Gas Welding 3. Consumable electrode wire
S. Electroslag Welding 4. Joining of cylindrical dissimilar materials

In a DC arc welding operation, the voltage-arc length characteristic was obtained as Varc = 20 + 5l where the arc length l was varied between 5 mm and 7 mm. Here Varc denotes the arc voltage in Volts. The arc current was varied from 400 A to 500 A. Assuming linear power source characteristic, the open circuit voltage and the short circuit current for the welding operation are

Which one among the following welding processes uses non-consumable electrode?

Two pipes of inner diameter 100mm and outer diameter 110mm each joined by flash butt welding using 30V power supply. At the interface, 1mm of material melts from each pipe which has a resistance of 42.4Ω. If the unit melt energy is 64.4MJm-3, then time required for welding in seconds is

In arc welding of a butt joint, the welding speed is to be selected such that highest cooling rate is achieved. Melting efficiency and heat transfer efficiency are 0.5 and 0.7, respectively. The area of the weld cross section is 5mm2 and the unit energy required to melt the metal is 10 J/mm3. If the welding power is 2 kW, the welding speed in mm/s is closest to

Which one of the following is a solid state joining process?

A direct current welding machine with a linear power source characteristic provides open circuit voltage of 80 V and short circuit current of 800 A. During welding with the machine, the measured arc current is 500 A corresponding to an arc length of 5.0 mm and the measured arc current is 460 A corresponding to an arc length of 7.0 mm. The linear voltage (E) – arc length (L) characteristic of the welding arc can be given as (where E is in Volt and L is in mm)

Two metallic sheets, each of 2.0 mm thickness, are welded in a lap joint configuration by resistance spot welding at a welding current of 10 kA and welding time of 10 millisecond. A spherical fusion zone extending up to the full thickness of each sheet is formed. The properties of the metallic sheets are given as:

ambient temperature = 293 K  
melting temperature = 1793 K density = 7000 kg/m3
latent heat of fusion = 300 kJ/kg specific heat = 800 J/kg K

Assume : (i) contact resistance along sheet – sheet interface is 500 micro-ohm and along electrode – sheet interface is zero; (ii) no conductive heat loss through the bulk sheet materials; and (iii) the complete weld fusion zone is at the melting temperature.

The melting efficiency (in %) of the process is