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# GATE Past Year Questions: Joining Processes Notes | EduRev

## Mechanical Engineering : GATE Past Year Questions: Joining Processes Notes | EduRev

The document GATE Past Year Questions: Joining Processes Notes | EduRev is a part of the Mechanical Engineering Course Manufacturing Engineering.
All you need of Mechanical Engineering at this link: Mechanical Engineering

Try yourself:A 900 mm long steel plate is welded by manual metal arc welding process using welding current of 150 A, arc voltage of 20 V and welding speed of 300 mm/min. If the process efficiency of is 0.8 and surface resistance is 36 micro-ohm, the heat input in J/mm

[PI 2003]

Try yourself:In resistance welding, heat is generated due to the resistance between

[PI 2003]

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

[ME 2018,Set-1]

Try yourself:Two pipes of inner diameter 100 mm and outer diameter 110 mm each are joined by flash butt welding using 30 V power supply. At the interface, 1 mm of material melts from each pipe which has a resistance of 42.4 ohms. If the unit melt energy is 64.4 MJ/m3, then time required for welding (in s) is

[ME 2010]

Try yourself:Spot welding of two 1 mm thick sheets of steel (density = 8000 kg/m3) 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 μ-ohms, the current passing through the electrodes is approximately

[ME 2005]

Try yourself:The strength of a brazed joint

[ME 2005]

Try yourself: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 0.25 sec. Assuming the interface resistance to be 0.0001 ohms. The heat generated to form the weld is

[ME 2001]

Try yourself:For resistance spot welding of 1.5 mm thick steel sheets, the current required is of the order

[ME 1991]

Try yourself:Which of the following welding process results in the smallest heat affected zone?

[PI 2011]

Try yourself:During a steady gas metal arc welding with direct current electrode positive polarity, the welding current, voltage and weld speed are 150 A, 30 V and 6 m/min respectively. A metallic wire electrode of diameter 1.2 mm is being fed at a constant rate of 12 m/min. The density, specific heat and melting temp of the wire electrode are 7000 kg/m3, 500 J/kg and 1530°C respectively.
Assume the ambient temp to be 30°C and neglect the latent heat of melting. Further consider that 2/3rd of the total electrical power is available for melting of the wire electrode. The melting efficiency (in percentage) of the wire electrode is

[PI 2010]

Try yourself:Autogeneous gas tungsten arc welding of a steel plate is carried out with welding current of 500 A. Voltage of 20 V and weld speed of 20 mm/ min. Consider the heat transfer efficiency from the arc to the weld pool as 90%. The heat input per unit length (in kJ/mm) is

[PI 2009]

Try yourself:The DC power source for are welding has the characteristic 3V + I = 240, where V = Voltage and I = Current in amp. For maximum are power at the electrode, voltage should be set at

[PI 2007]

Try yourself:The current in Amperes used in resistance spot welding of plain carbon steel sheets (1 to 3 mm thick) lies within the range

[PI 2004]

Try yourself:Which of the following process can be used for welding of Aluminum alloys?
P. Submerged arc welding
Q. Gas metal arc welding
R. Electroslag welding
S. Gas tungsten arc welding

[PI 2003]

Try yourself:The voltage arc length characteristics of a DC arc is given by V = 20 + 40L, where L = arc length in cm. The power source characteristics can be approximated by a straight line. Open circuit is 80 V and short circuit current 1000 Amps. The optimum arc length in mm

[PI 1991]

Try yourself:High alloy steel components are preheated before welding for reducing

[PI 1991]

Try yourself:The mode of metal transfer in CO2-MIG welding at low temperature is

[PI 1990]

Try yourself: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

[ME 2017,Set-1]

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

[ME 2016,Set-2]

Try yourself: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 voltage and heat input to the material so that weld quality remains the same. The welding current (in A) for this process is ___________ .

[ME 2015,Set-2]

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

[ME 2015,Set-1]

Try yourself: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

[ME 2012]

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

[ME 2011]

Try yourself: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 mm2 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

[ME 2008]

Try yourself: 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 Voit and L is in mm)

[ME 2007]

Try yourself:In an arc welding process, the voltage and current are 25 V and 300 A respectively. The arc heat transfer efficiency is 0.85 and welding speed is 8 mm/s. The net heat input (in J/mm) is

[ME 2006]

Try yourself: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

[ME 2004]

Try yourself:Which of the following arc welding processes does not use consumable electrode

[ME 2002]

Try yourself: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

[ME 2002]

Try yourself:Preheating before welding is done to

[ME 1996]

Try yourself:The electrodes used in arc welding are coated.This is not expected to

[ME 1994]

Try yourself:In DC welding, the straight polarity (electrode negative) results in

[ME 1993]

Try yourself:At small variations of arc length at operating conditions, the manual metal arc welding transformer provides nearly

[ME 1990]

Try yourself:Penetration is increased by

[ME 1990]

Try yourself:Which of the following powders should be fed for effective oxy-fuel cutting of stainless steel.

[PI 2001]

Try yourself:During gas welding of copper sheets a neutral flame was used consuming 8 litres of acetylene.But the weld was found to be defective. So it was rewelded using an oxidizing flame. The likely consumption of oxygen in litres will be

[PI 1993]

Try yourself:In welding a mild steel sheet using an oxyacetylene flame, the total amount of acetylene consumed was 8.0 litres, the oxygen consumption from the cylinder is

[PI 1989]

Try yourself:The temperature of a carburizing flame in gas welding that of a neutral or an oxidizing flame

[ME 2002]

Try yourself:For butt welding 40 mm 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.

[ME 1999]

Try yourself:For gas welding a particular job using a neutral oxyacetylene flame the acetylene consumption was 10 litres. The oxygen consumption from the cylinder in liters will be

[ME 1991]

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## Manufacturing Engineering

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