I just noticed the same, against 40d#16:
http://www.bay12games.com/forum/index.php?topic=46988.0Summary: several of us see the same behaviour with unmodded dwarves, trying to melt various metal chests. IronyOwl reports that the dwarf works on the chest for a while, gets experience for doing the job, consumes a unit of fuel, but the chest survives, still designated for melting (I was having the problem on a magma forge, no fuel required). Contra: Hyndis reports seeing chests disappear without issue.
All other items, including furniture (even cabinets), melt down without issue.