Final answer:
Mild steel, which has up to 0.25% carbon, is relatively easy to gas weld compared to high carbon steel due to its greater ductility and lower brittleness.
Step-by-step explanation:
The correct answer is option mild steel is not one of the more difficult metals to gas weld. In comparison to high carbon steel which contains up to about 1.5% carbon and is very hard but also more brittle, mild steel has a much lower carbon content of up to about 0.25%.
The presence of carbon in this amount makes it stronger and harder than wrought iron, which is basically pure iron, but allows it to retain enough ductility and malleability for welding.
Due to its composition, mild steel is easier to work with when gas welding, making it suitable for a wide range of applications, such as car bodies, ship building, girders, and bridges. On the other hand, high carbon steel's brittleness can make it more challenging to weld without cracking.