Question

In an arc welding process of mild steel with a potential of 25V and current of 200 A, the travel speed is 5 mm/sec and the cross-sectional area of joint is 20 mm${}^2$. Heat required to melt steel is 10 J/mm${}^3$ and the heat transfer efficiency is 0.8. The melting efficiency is _______(%).

• A. 10
• B. 30
• C. 25
• D. 15

Answer 1

The correct option is C 25

$H_m=10J/m{m}^3$

$H_s=\frac{VI}{A_w{V}_w}\times {\eta }_{HT}$

$=\frac{25\times 200}{20\times 5}\times 0.8=40J/m{m}^3$

${\eta }_m=\frac{H_m}{H_s}=\frac{10}{40}=25$