GATE 2018 ME (ME2) – Question 63
A welding operation uses 30 V and 100 A. Weld-bead cross-sectional area is 20 mm². Workpiece and filler are titanium with specific melting energy 14 J/mm³. Thermal efficiency is 70%. Find welding speed (mm/s), to two decimal places.
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Correct answer: 7.49 to 7.51
Explanation
Useful melting power is $\eta VI=0.7(30)(100)=2100$ J/s. At speed v, bead volume rate is 20v mm³/s and required melting power is $14(20v)=280v$ J/s. Hence $v=2100/280=$ **7.50 mm/s**.