[chmforever]

in addition to thermite reaction  , is there any other reaction

[enahs]

I am guessing you want something that is slow and pretty and exotic like thermite? I mean, there are many chemical explosives that get hot enough to melt steal, they just react so fast they explode.

Steel is an alloy, and so the melting point changes with composition.

The combustion of acetylene is a chemical reaction, and it is used to melt steal every day.

etc, etc.