Question $2(15$ Marks$)$

For structural steels, explain what is meant by:

$($i$)$ Carbon Equivalent $($CE$)$

$($ii$)$ Weldability

A steel floor girder in an existing building needs to be strengthened by welding a structural member to its bottom flange. The steel grade is unknown, but material testing has revealed the following percentages by weight of the following alloy chemical elements in the girder:

$C=0\mathrm{.}16\%,Cr=0\mathrm{.}10\%,Cu=0\mathrm{.}20\%,Mn=0\mathrm{.}8\%,Mo=0\mathrm{.}15\%,Ni=0\mathrm{.}25\%,V=0\mathrm{.}06\%,Si=0\mathrm{.}20\%.$

Calculate the $CE$ and determine the weldability of the structural steel.