There are evidence that the steel, unlike moder steel, which would have shown evidence of bending in a collision, appeared to have shattered on impact with the iceberg. Further analysis has shown that the steel used to construct the hull of the Titanic was high in sulfur content, and it is known that sulfur occlusions tend to make steel more brittle. There were another analysis made that suggested that the rivets contain three times the expected amount of silicate slag. The high slag content resulted in weak rivets that snapped in large numbers when the collision occurred, mortally wounding the ship.
On the other hand they would have known this before the Titanic disaster, when Olympic crashed with Hawke, but why didn't they react? There must have been some kind of invetigations etc...