Submitted by Zeoinx t3_zzxffx in explainlikeimfive
So its not so much how do forges melt metals, so much as How do forges melt steel and transport the molten steel without melting the container containing the steel as well. This part has always nagged me in the back of my head and I always forget to find out how this is possible.
phiwong t1_j2e67cs wrote
While steel melts at a relatively high temperature relative to other metals like copper, aluminium, gold, silver and tin etc, it is not at a temperature that is unimaginably high. (maybe 1.5x to 3x).
Things like stone, ceramics, clay and sand can easily withstand the melting temperature of steel. All you need is to make the container out of this kind of materials. (This is why the forge doesn't melt when steel is melted)
There are also other metals that have higher melting points than steel - titanium for example. But titanium is way too expensive to make into forging containers - a simple clay container is sufficient.