Welding Process · Production Engineering · GATE ME
Marks 1
1
The most suitable electrode material used for joining low alloy steels using Gas Metal Arc Welding (GMAW) process is
GATE ME 2024
2
Two surfaces P and Q are to be joined together. In which of the given joining operation(s), there is no melting of the two surfaces P and Q for creating the joint?
GATE ME 2023
3
Which of the following heat treatment processes is/are used for surface hardening of steels?
GATE ME 2022 Set 1
4
Which of the following additive manufacturing technique(s) can use a wire as a feedstock material?
GATE ME 2022 Set 1
5
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
GATE ME 2017 Set 1
6
Under optimal conditions of the process the temperatures experienced by a copper work piece in fusion welding, brazing and soldering are such that
GATE ME 2016 Set 1
7
Which two of the following joining processes are autogeneous?
$$(i)$$ Diffusion welding
$$(ii)$$ Electro slag welding
$$(iii)$$ Tungsten inert gas welding
$$(iv)$$ Friction welding
$$(i)$$ Diffusion welding
$$(ii)$$ Electro slag welding
$$(iii)$$ Tungsten inert gas welding
$$(iv)$$ Friction welding
GATE ME 2015 Set 3
8
In a linear arc welding process, the heat input per unit length is inversely proportional to
GATE ME 2015 Set 1
9
Within the Heat Affected Zone (HAZ) in a fusion welding process, the work material undergoes
GATE ME 2014 Set 4
10
The major difficulty during welding of aluminium is due to its
GATE ME 2014 Set 1
11
In solid-state welding, the contamination layers between the surfaces to be welded are removed by
GATE ME 2014 Set 1
12
Which one among the following welding processes uses non-consumable electrode?
GATE ME 2011
13
Which of the following is a solid state welding process.
GATE ME 2007
14
The strength of a brazed joint
GATE ME 2005
15
In Oxyacetylene gas welding, temperature at the inner cone of the flame is around
GATE ME 2003
16
Which of the following arc welding processes does not use consumable electrode
GATE ME 2002
17
The temperature of a carburizing flame in gas welding is _______ that of a neutral or an oxidizing flame.
GATE ME 2002
18
Two plates of the same metal having equal thickness are to be butt welded with electric arc. When the plate thickness changes, welding is achieved by
GATE ME 2001
19
Preheating before welding is done to
GATE ME 1996
20
Generally cylindrical parts produced by powder metallurgy should not have non uniform cross section and a length to diameter ratio exceeding . . . . . . . . . . . . . . .
GATE ME 1994
21
The ratio of acetylene to oxygen is approximately ................ for neutral flame used in gas welding
GATE ME 1994
22
The electrodes used in $$arc$$ welding are coated. This coating is not expected to
GATE ME 1994
23
In $$DC$$ welding, the straight polarity (electrode negative) results in
GATE ME 1993
24
In an explosive welding process, the ..................... (maximum/minimum) velocity of impact is fixed by the velocity of sound in the ............. (flyer / target) plate material.
GATE ME 1992
25
For resistance spot welding of $$1.5$$ $$mm$$ thick steel sheets, the current required is of the order
GATE ME 1992
26
For gas welding a particular job using a neutral oxy-acetylene flame the acetylene consumption was $$10$$ ltrs. The oxygen consumption from the cylinder in liters will be
GATE ME 1991
27
At small variations of are length at operating conditions, the manual metal are welding transformer provides nearly
GATE ME 1990
28
Penetration is increased by
GATE ME 1990
Marks 2
1
In an arc welding process, the voltage and current are 30 V and 200 A, respectively. The cross-sectional area of the joint is 20 mm2 and the welding speed is 5 mm/s. The heat required to melt the material is 20 J/s. The percentage of heat lost to the surrounding during the welding process is _______ (rounded off to 2 decimal places).
GATE ME 2024
2
In a direct current arc welding process, the power source has an open circuit voltage of 100 V and short circuit current of 1000 A. Assume a linear relationship between voltage and current. The arc voltage (V) varies with the arc length (l) as V = 10 + 5l where V is in volts and l is in mm. The maximum available arc power during the process is ______ kVA (in integer).
GATE ME 2022 Set 2
3
Two mild steel plates of similar thickness, in butt-joint configuration, are welded by gas tungsten arc welding process using the following welding parameters.
$$ \begin{array}{|l|l|} \hline \text { Welding voltage } & 20 \mathrm{~V} \\ \hline \text { Welding current } & 150 \mathrm{~A} \\ \hline \text { Welding speed } & 5 \mathrm{~mm} / \mathrm{s} \\ \hline \end{array} $$A filler wire of the same mild steel material having 3 mm diameter is used in this welding process. The filler wire feed rate is selected such that the final weld bead is composed of 60% volume of filler and 40% volume of plate material. The heat required to melt the mild steel material is 10 J/mm3. The heat transfer factor is 0.7 and melting factor is 0.6. The feed rate of the filler wire is __________ mm/s (round off to one decimal place).
GATE ME 2022 Set 1
4
The voltage - length characteristic of a direct current arc in an arc welding process is $$V=$$ $$(100+40l),$$ 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 $$2$$ $$mm$$ and the welding current is the range $$200$$-$$250A$$. Assuming a linear power source, the short circuit current is _____________$$A.$$
GATE ME 2016 Set 2
5
Spot welding of two steel sheets each $$2$$ $$mm$$ thick 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 ______________$$mm.$$
GATE ME 2016 Set 3
6
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 $$120mm/min$$ 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
GATE ME 2015 Set 2
7
A $$DC$$ welding power source has a linear voltage-current $$(V$$-$$I)$$ characteristic with open circuit voltage of $$80V$$ and a short circuit current of $$300A.$$ For maximum arc power, the current (in Amperes) should be set as _______________
GATE ME 2015 Set 1
8
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 $$8mm$$ and width is $$20mm.$$ Improper selection of welding parameters caused an undercut of $$3mm$$ depth along the weld. The maximum transverse tensile load (in $$kN$$) carrying capacity of the developed weld joint is _________________
GATE ME 2014 Set 4
9
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 $$1000J.$$ Assuming that the heat required for melting $$1m{m^3}$$ volume of steel is $$20J$$ and interfacial contact resistance between sheets is $$0.0002$$$$\Omega $$, the volume (in $$m{m^3}$$) of weld nugget is _____________
GATE ME 2014 Set 3
10
In a $$DC$$ $$arc$$ welding operating, the length characteristic was obtained as $${V_{arc}} = 20 + 5l$$ where the $$arc$$ length $$l$$ was varied between $$5mm$$ and $$7mm.$$ Here $${V_{arc}}$$ denotes the arc voltage in volts. The $$arc$$ current was varied from $$400A$$ to $$500A.$$ Assuming linear power source characteristic, the open circuit voltage and the short circuit current for the welding operation are
GATE ME 2012
11
Two steel bars each of diameter $$10mm$$ are coaxially friction welded end to end at an axial pressure of $$200MPa$$ and rotational speed of $$400rpm$$. The coefficient of friction between the mating faces of the rotating bars is $$0.50.$$ The torque is assumed to act at the $$3/{4^{th}}$$ radius of the rotating bar. The power (in $$kW$$) consumed at the interface of the welding is
GATE ME 2010
12
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 $$5$$ $$m{m^2}$$ and the unit energy required to melt the metal is $$10\,\,J/m{m^3},$$ if the welding power is $$2$$ $$kW,$$ the welding speed in $$mm/s$$ is closet to
GATE ME 2008
13
Two metallic sheets, each of $$2.0$$ $$mm$$ thickness are welded in lap joint configuration by resistance spot welding at a welding current of $$10$$ $$KA$$ and welding time of $$10$$ milliseconds. A spherical fusion zone extending up to the full thickness of each sheet is formed. The properties of the metallic sheets are given below:
Ambient temp $$=293$$ $$K$$
Melting point temp $$=1793$$ $$K$$
Density $$ = 7000kg/{m^3}$$
Latent heat of fusion $$=300$$ $$kJ/kg$$
Specific heat $$=800$$ $$J/kgK$$
Ambient temp $$=293$$ $$K$$
Melting point temp $$=1793$$ $$K$$
Density $$ = 7000kg/{m^3}$$
Latent heat of fusion $$=300$$ $$kJ/kg$$
Specific heat $$=800$$ $$J/kgK$$
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 material; and
(iii) The complete weld fusion zone is at the melting temperature, the melting
$$\,\,\,\,\,\,\,\,\,$$efficiency (in %) of the process is .........
GATE ME 2007
14
A $$DC$$ welding machine with a linear power source characteristic provides open circuit voltage of $$80V$$ and short circuit current of $$800A,$$ during welding with the machine , the measured are current is $$500A$$ corresponding to an arc length of $$5.0$$ $$mm$$ and the measured are current $$460A$$ 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 Volts and $$L$$ is in $$mm$$)
GATE ME 2007
15
In arc welding process, the voltage and current are $$25V$$ and $$300A$$ respectively. The arc heat transfer efficiency is $$0.85$$ and welding speed is $$8$$ $$mm/sec$$. The net heat input (in $$J/mm$$) is
GATE ME 2006
16
Spot welding of two $$1$$ $$mm$$ thick sheets of steel (density $$ = 8000kg/{m^3}$$ ) is carried out successfully by passing a certain amount of current for $$0.1$$ second through the electrodes. The resultant weld nugget formed is $$5$$ $$mm$$ in diameter and $$1.5$$ $$mm$$ thick. If the latent heat of fusion of steel is $$1400$$ $$kJ/kg$$ and the effective resistance in the welding operation is $$200\mu \Omega ,$$ the current passing through the electrodes is approximately
GATE ME 2005
17
Two 1 mm thick steel sheets are to be spot welded at a current of $$5000$$ $$A.$$ Assuming effective resistance to be $$200$$ micro-ohms and current flow time of $$0.2$$ second, heat generated during the process will be
GATE ME 2004
18
Match the following
GATE ME 2003
19
resistance spot welding is performed on two plates of $$1.5$$ $$mm$$ thickness with $$6$$ $$mm$$ diameter electrode, using $$15000$$ $$A$$ current for a time duration of $$0.25sec$$. assuming the interface resistance to be $$0.0001\Omega ,$$ the heat generated to form the weld is
GATE ME 2001
20
GATE ME 1996
21
GATE ME 1991
Marks 5
1
The arc - voltage characteristics of a $$DC$$ power source has a linear power source characteristic of $$V=20+40L,$$ where $$V$$ is the arc voltage in volts and $$L$$ is the arc length in $$cm.$$ The static volt-ampere characteristic of the power source is approximated by a straight line with open circuit voltage $$=80V$$ and short circuit current is $$600Amps,$$ determine the optimum arc length for maximum power
GATE ME 2003
2
Two different pairs of sheets of same material are welded by resistance-spot welding. In one pair, the average radius $$(r)$$ of each spherical bridge is $$0.2$$ $$mm$$ and the number of bridges per $$c{m^2}\,\,\left( n \right)$$ is $$25.$$ In another pair, the number of bridges per $$c{m^2}$$ is $$50$$ with the same $$'r'$$ of bridge. The contact resistance $${R_c}$$ per unit area is given by $${R_c} = 0.85$$ $$\left( {\rho /n\pi r} \right)$$ where $$'\,\rho \,'$$ is the resistivity of metal. If the voltage applied is $$5$$ volts and the resistivity of metal is $$2 \times {10^{ - 5}}$$ ohm-cm. The rate of heat generated per $$c{m^2}$$ in each case
GATE ME 2000
3
In butt welding operation on plates, the heat input necessary is given by
$$Q = 8\,K\,{T_c}\,t\,\,\,\left[ {0.2 + {{Vb} \over {4\alpha }}} \right]$$
Where $$K=$$ thermal conductivity,
$${T_c} = $$ temp increases from room temp up to $$MP,$$
$$t=$$ thickness of plate,
$$V=$$ welding speed,
$$b=$$ width of weld,
$$\alpha = thermal diffusivity
Two alloy steel plates as shown in fig are to be welded using a power source rated at $$5$$ $$kVA$$ having a duty cycle of $$75\% .$$ Using the given data, determine the maximum welding speed for the job given in $$mm/s$$
Data : $$K = 45\,W/{m^0}C,\,\,{T_c} = {1450^ \circ }C,$$ and
$$\alpha = 1.2 \times {10^{ - 5}}\,\,{m^2}/s.$$
GATE ME 1999
4
For butt welding $$40mm$$ thick steel plates, when the expected quantity of such jobs is $$5000$$ per month over a period of $$10$$ years, choose the best suitable welding process out of the following available alternatives.
GATE ME 1999
5
The voltage-arc length characteristics of a $$DC$$ arc is given by $$V=20+4L.$$ Where $$L$$ is in $$mm$$. During a welding operation arc length is expected to vary between $$4$$ and $$6$$ $$mm$$ with the welding current limited between $$450$$ and $$550$$amps.
If the power source has a linear characteristic, the open circuit voltage is.
GATE ME 1998
6
The voltage-arc length characteristics of a $$DC$$ arc is given by $$V=20+4L.$$ Where $$L$$ is in $$mm$$. During a welding operation arc length is expected to vary between $$4$$ and $$6$$ $$mm$$ with the welding current limited between $$450$$ and $$550$$amps.
The arc power at an arc length of $$5mm$$ is
GATE ME 1998
7
Welding of $$C40$$ steel plate of $$10mm$$ thickness required a current of $$16$$amps, while it was $$360$$amps when the plate thickness was increased by $$50\% $$. Estimate the welding current for $$8mm$$ thickness of same material.
GATE ME 1997
8
The cross section weld bead is shown in fig the profile of the bead and the fusion zone are taken circular for convenience. Bead width and radii of curvature of circular profiles are given in fig. The bead height and depth of penetration are
GATE ME 1996
9
A low carbon steel is to be welded by the manual metal arc welding process using a linear $$V$$-$$I$$ characteristic $$DC$$ power source.
The following data is available.
$$O.C$$ voltage of the power source $$=62V,$$
$$S.C$$ current for the setting used $$=130A,$$
ARC length $$=4mm,$$
Traverse speed of welding $$=15cm/min$$
Efficiency of heat input $$ = 85\% $$
The relation between the arc length $$L$$ in $$mm$$
and arc voltage $$V$$ is $$V=20+1.5L$$
Calculate the heat input into the work piece.
GATE ME 1992
10
Manual metal arc welding is to be used for welding two plates each measuring $$800 \times 200 \times 19mm.$$ Given that
Length of weld $$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,\,$$$$:180mm$$
Length of electrode$$\,\,\,\,\,\,\,\,\,\,\,$$ $$:450mm$$
Stub length$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,\,$$ $$:50mm$$
Diameter of electrode $$\,\,\,\,\,$$ $$:3mm$$
Weld reinforcement area $$:10\% $$
Spatter and other losses $$:15\% $$
Root gap $$=$$ land $$=$$ $$2mm$$
Angle of groove$$\,\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,$$ $$:{60^ \circ }$$
Estimate the required number of electrodes for the weld.
Length of weld $$\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,\,$$$$:180mm$$
Length of electrode$$\,\,\,\,\,\,\,\,\,\,\,$$ $$:450mm$$
Stub length$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,\,\,$$ $$:50mm$$
Diameter of electrode $$\,\,\,\,\,$$ $$:3mm$$
Weld reinforcement area $$:10\% $$
Spatter and other losses $$:15\% $$
Root gap $$=$$ land $$=$$ $$2mm$$
Angle of groove$$\,\,\,\,\,\,\,\,\,\,\,$$$$\,\,\,\,\,\,\,\,\,$$ $$:{60^ \circ }$$
Estimate the required number of electrodes for the weld.
GATE ME 1990
11
An arc welding $$DC$$ power source has a linear power source characteristic with open circuit voltage $${V_O} = \,\,80$$ volts and short circuit current $${{\rm I}_S} = 1000amps.$$ The voltage-length characteristic of the arc is given by $$V=20+4L$$ volts where $$L$$ is the arc length in $$mm,$$ calculate the optimum length of arc for obtaining maximum arc power at welding. What voltage and current setting should be done on the power source for maximum arc power.
GATE ME 1989