The $$DC$$ power source for arc welding has the characteristic $$3V + 1 = 240,$$ where $$V=$$ Voltage and $${\rm I}\,\, = $$ current in amp. For maximum arc power at the electrode, voltage should be set at

Two $$8$$ $$mm$$ thick steel plates are placed $$5$$ $$mm$$ apart and welded by a butt joint. Welding is carried out at $$20$$ $$V$$ and speed of $$5$$ $$mm/sec.$$ Heat transfer efficiency is $$0.80.$$ If the heat required to melt steel is $$10$$ $$J/m{m^3}$$ and melting efficiency is $$0.625.$$ The weld current (in Amperes) will be

Consider the following statements :

The magnitude of residual stresses in welding depends upon
$$1.$$ Metal melted / deposited
$$2.$$ Design of weldment
$$3.$$ Support and clamping of components
$$4.$$ Welding process used

Which of the statements given above are correct?

Consider the following statements:

The size of the heat affected zone (HAZ) will increase with
$$1.$$ increased starting temperature
$$2.$$ increased welding speed
$$3.$$ increased thermal conductivity of the base metal
$$4.$$ increase in base metal thickness

Which of the statements given above are correct?