GATE PI topic:joining-materials PYQs & Answers

Questions 1–10 of 18. Imported answers require independent review unless marked reviewed.

Which ONE of the following is FALSE with respect to filler material used in brazing?

Your answerChoose one option.

Melting temperature of the filler material must be less than the base metal.

Wettability of the base metal by the filler material must be low.

Viscosity of the filler material must be low for penetration into the interface.

Chemical reactivity between the filler material and the base metal must be low.

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An arc welding process is being carried out with a power source of 6 kW to weld two similar metals. The total energy loss is 50%, the area of cross-section of the weld is 10 mm

, and the specific energy needed to melt the metal is 15 J/mm

The speed of welding is _____ mm/s.

Your answerChoose one option.

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Exit-hole occurrence is common in

Your answerChoose one option.

Electron Beam Welding

Submerged Arc Welding

Friction Welding

Friction Stir Welding

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In a direct current arc welding, the voltage V (in volt) is related to the arc length l (in cm) as

The open circuit voltage is 80 volts. The maximum possible arc length (in cm) is________. (Rounded off to two decimal places)

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Which among the following is/are TRUE for friction stir welding (FSW) process?

Your answerSelect all correct options. You can choose more than one.

It can be used to produce lap, butt and tee joints.

A non-consumable rotating tool with shoulder and pin is used to melt the work-piece material.

Retreating side of the weld is where the linear velocity vector at a point on that side of the rotating tool and the weld direction are opposite.

Advancing side of the weld is where the linear velocity vector at a point on that side of the rotating tool and the weld direction are opposite.

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Mild steel plates are welded to make butt joints by arc weld with 85% heat transfer efficiency ignoring other losses. The first weld joint is made by selecting arc voltage of 30 V and current of 180 A with a welding speed of 6 mm/s. Using identical plates, a second weld joint is made with the same arc voltage and a welding speed of 8 mm/s. If both the welds have the same heat input, then the welding current (in A) for the second weld joint is ________. (Answer in integer)

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Two metal sheets are joined using resistance spot welding. A weld current of 4500 A is applied for 0.2 s. The effective contact resistance at the sheet interface is

. The thermal efficiency of the weld process is 50 %. The amount of heat, in J, used for producing a spot weld is _____(in integer).

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An arc welding operation is performed at 25 V and 200 A at welding speed of 2 mm/s. The heat used for melting is 80 % of the total heat generated. The unit melting energy of the metal to be joined is 10 J/mm³. The volume of the weld metal produced per unit time, in mm³/s, is _____ (in integer).

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In a gas tungsten arc welding process under steady state condition, the input voltage and current are measured as 18 V and 160 A, respectively. Heat loss during creation of arc is 40% of the input power. Heat loss through convection and radiation from the workpiece is 800 W. The effective power (in W) utilized to melt the workpiece is____________. [round off to nearest integer]

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Which one of the following defects is NOT associated with welding processes?

Your answerChoose one option.

Angular distortion

Hot tear

Hydrogen embrittlement

Earing

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GATE PI topic:joining-materials PYQs

How to practice topic:joining-materials

Question 12

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Question 7