1

GATE PI 2009

MCQ (Single Correct Answer)

+5

-1.5

Resistance spot welding of two steel sheets is carried out in lap joint configuration by using a welding current of $$3$$ $$KA$$ and a weld time of $$0.2s.$$ A molten weld nugget of volume $$20m{m^3}$$ is obtained. The effective contact resistance is $$200\mu \Omega .$$ The material properties of steel are given as (i) latent heat of melting $$1400$$ $$kJ/kg,$$ (ii) density $$8000$$ $$kg/{m^3},$$ (iii) melting temp $${1520^ \circ }C$$, (iv) specific heat $$0.5$$ $$kJ/kgC.$$ The ambient temp is $$20C.$$

Heat (in Joules) used for producing weld nugget will be (assuming $$100\% $$ heat transfer efficiency

2

GATE PI 2009

MCQ (Single Correct Answer)

+5

-1.5

Resistance spot welding of two steel sheets is carried out in lap joint configuration by using a welding current of $$3$$ $$KA$$ and a weld time of $$0.2s.$$ A molten weld nugget of volume $$20m{m^3}$$ is obtained. The effective contact resistance is $$200\mu \Omega .$$ The material properties of steel are given as (i) latent heat of melting $$1400$$ $$kJ/kg,$$ (ii) density $$8000$$ $$kg/{m^3},$$ (iii) melting temp $${1520^ \circ }C$$, (iv) specific heat $$0.5$$ $$kJ/kgC.$$ The ambient temp is $$20C.$$

Heat (Joules) dissipated to the base metal will be (neglecting all other heat losses)

3

GATE PI 2003

MCQ (Single Correct Answer)

+5

-1.5

A weld is made using $$MIG$$ welding process with the following welding parameters: Current: $$200A;$$ Voltage: $$25V;$$ Welding speed: $$18$$ $$cm/min;$$ wire diameter: $$1.2$$ $$mm;$$ Wire feed rate: $$4$$ $$m/min;$$ Thermal efficiency of the process: $$65\% $$

The heat input per unit length of the weld in $$kJ/cm$$ is:

4

GATE PI 2003

MCQ (Single Correct Answer)

+5

-1.5

A weld is made using $$MIG$$ welding process with the following welding parameters: Current: $$200A;$$ Voltage: $$25V;$$ Welding speed: $$18$$ $$cm/min;$$ wire diameter: $$1.2$$ $$mm;$$ Wire feed rate: $$4$$ $$m/min;$$ Thermal efficiency of the process: $$65\% $$

The area of cross section of weld bead in $$m{m^2}$$ is:

Questions Asked from Welding (Marks 5)

Number in Brackets after Paper Indicates No. of Questions

GATE PI Subjects

Fluid Mechanics

Metrology

Theory of Machines

Engineering Mathematics

Machine Tools and Machining

Industrial Engineering

Engineering Mechanics

Strength of Materials

Thermodynamics

Machine Design

Casting

Joining of Materials

Metal Forming