Molybdenum Solid Solution Strengthening at High Temperatures

Molybdenum in steel causes solid solution strengthening. That means the Mo atoms lodge in the lattice and block dislocation glide. This keeps the steel strong even at high temperatures and it doesn't creep as fast. When welding, you have to watch out that the heat doesn't coarsen the structure. Then the steel becomes brittle and prone to cracking. Keep the interpass temperature low and let the part cool slowly after welding, then the structure stays fine and tough.