In grad school my advisor (who was teaching "Launch and Entry Systems") told us this story. A few lectures later he went over rail guns as a launch system, and

In grad school my advisor (who was teaching "Launch and Entry Systems") told us this story. A few lectures later he went over rail guns as a launch system, and mentioned that by his back-of-the-envelope calculations, a slug of titanium the size of a telephone pole, launched at earth escape velocity by a rail gun at sea level, would ablate approximately a third of its length away in the first thousand meters, or something close to that (it's been a long time). Actually calculating the heating of a steel plate launched at that speed is a significantly nontrivial problem, because its aerodynamics are unstable. In other words, it would almost certainly tumble in flight, in an unpredictable manner. There's no guarantee that it would even fly in anything approximating a straight line. Even figuring out the effective coefficient of drag would be really hard. Figuring out the thermal profile would be even harder. But, as several other comments have mentioned - no matter how you slice it, it would be subject to a hell of a lot of heating, and it's a pretty safe bet that it ablated completely away and did not reach space.