WEIDING

$($a$)$ You have been offered a weld design engineer role through a CDC placement. The manager

wants to test your understanding on the first day of joining. Your assignment is to train intems

with Gas Metal Are Welding of two stecl plates of suitable thicknesses in an old clectric supply

line. The manager provides you with the following data: Current $100$ A ; Voltage: $20$ V ;

Electrical efficiency of the supply line as per the electricity bill: $50\%$; Welding specd: $250$

$\frac{mm}{\text{m}\text{i}\text{n}}$; Wire diameter: $1\mathrm{.}0$ mm ; Wire feed rate: $5\frac{m}{\text{m}\text{i}\text{n}}$ Thermal efficiency of the process

is $17\mathrm{.}5\%.$ The manager wants you to determine $($i$)$ the heat input per unit length of the weld in

kJ per cm $,$ and $($ii$)$ area of erossesection of the weld bead in $m{m}^2.$

$($b$)$ Upon finding that you are able to solve the question $($a$),$ the manager is delighted and wants

you to identify the material of the electrode wire. You are now provided with the mass flow

rate, which is $0\mathrm{.}18\frac{g}{s},$ specific heat capacity of $904\frac{J}{k}gK,$ latent heat of melting of the wire is

$400k\frac{l}{k}g,$ ambient iemperature at the time of welding is $30C.$ Determine $($i$)$ the density, $($ii$)$

melting point of the electrode wire, and $($iii$)$ comment what could be the material of the wire.