It's actually well-known that there were fires in the Titanic's coal bunkers. I remember first reading about this way back in the mid 1990s (1995-1997) when I was somewhat obsessed with the subject. It's also been speculated for just as long that the heat might've affected the hull's properties, though this runs counter to the argument that the cold water might've contributed to making the metal more brittle.

This is by no means extraordinary: coal bunker fires were rather common back in the age of steamships. It was even discussed at the various admiralty inquests into the loss of the vessel.