1. Firstly, the pores and oxides on the surface of the parts were observed by scanning electron microscope, and the results showed that the water vapor oxidation reaction inside the parts was not sufficient.

2. The second is to seal the hole, such as sandblasting, shot blasting, plastic surgery, wax dipping, etc.

3. Finally, MC carbide is formed inside the powder particles to reduce the precipitation tendency at the boundary of the original particles.