Polishing should be to remove the dirt accumulated on the blade surface during long-term operation. The existence of dirt can easily make the impeller of steam turbine produce redundant centrifugal force, resulting in imbalance and vibration of the impeller. Generally speaking, it is not recommended to repair the blade bending with fire, because the bending must be within a certain range. Excessive bending may cause the impeller to fail to run (it will wear out the casing). If it just looks a little bent, it doesn't need to be repaired without affecting the use. Judging from the use of materials, baking with fire can easily change the material state of leaves locally, so will there be strength problems when using them?