So, let me get this straight. The iceberg struck the ship on the side and ripped it open just below the waterline. The iceberg was able to do this only because the hull metal had been weakened by a 1,000 degree fire. The fire had been burning for three weeks straight (presumably at or near 1,000 degrees). That necessarily implies that the external hull metal was sufficiently exposed to this 1,000 degree fire that it was weakened.
Now, I know for a fact that metal is a very good conductor of heat. That means that the external surface of the hull would have been at or near that 1,000 degree temperature if the internal surface was at that temperature. Now, I also know that the external surface of a ship's hull is in direct contact with the surrounding ocean. Now, I also know that the ocean consists mainly of water and that water boils at around 212 degrees F (the salt content of the ocean most likely changed this a little).
Which leads to a question: how come this boat was able to toddle along for three - three! - weeks without anyone noticing a big plume of steam coming off the side that was exposed to this 1,000 degree fire?
hah hah perhaps you are right. But remember people can walk across hot coals without being burned if they do so quickly because heat transfers gradually. There was a steady stream of water coursing across the surface of the hull never more than about 55 degrees. Eventually the temperature was only a few degrees above freezing, and with the water flowing, high turbulence mixed the heat into the volume of the water flowing across the hull. From a physics POV it is likely that even though the temperature inside might have been 1000 degrees, unless the ship stopped dead in the water (unknown) during its voyage the temperature might never have gotten high enough to create highly-visible steam.
I once read an article about the steel plates that were used in the construction of the Titanic and it was theorized that because it was of highly inferior composition (relative to today's standards), the extremely low temperatures caused it to effectively behave like a crystal instead of retaining characteristic flexibility of steel and so shattered on impact instead of remaining resilient.
One version of this ongoing fire scenario includes the idea that the ship's commanders kept the fire secret, which makes sense from a PR perspective knowing how important success of the voyage was to the owners/builders. This would also explain the anomalous weakness of the plate at the site of impact only from a different cause than extreme cold alone.
