And I don‘t mean a small, little fire. I mean a big, continues flame.
It would depend on what metal the bars are made of. Steel has a very high melting point, around 2500 degrees F. Tin, however, melts at 482 degrees F, which a hot house fire could easily reach. Most house fires don't exceed a temp of 1700 degrees for an extended period of time. Copper, brass, gold and lead have very low melting points. Heat would make even hardened steel (as opposed to cast iron) more brittle if applied in a single area for an extended period of time, but that would not melt it, just make it more likely to bend or break. So be a little more specific in your question and you will get a more specific answer.
completely depends on the source of the fire and the heat, also the size and type of the metal bars. There are many things to be considered. Typically, they wouldn't melt though; so, forever?
