What were the three things that lead to the Titanic's demise?

Another thing that led (not "lead") to the Titanic's destruction recently came to light. It seems that the shipyards used substandard iron for the rivets on the vessel. It wasn't that they were cheap, but that they were contracted to build several monster ships in a limited space of time, so they used what materials they were able to get their hands on. But the fact remains, the rivets were substandard. Samples that have been pulled up from the wreck show large concentrations of slag in the rivets, which means they were of poor quality. Naturally, sadly (and in my estimation inexcusably after such a long time has ped), the company denies using substandard materials in any part of the construction--even though company doents have been found that corroborate that lower-quality steel was being used.