The effects of high energy electron beam remelting on the microstructure and properties of piston throat were compared under different casting processes and hydrogen content. The results show that under the same process parameters of high energy electron beam remelting

the penetration of gravity casting piston sample is greater than that of squeeze casting piston sample

and the hardness of remelting zone is lower than that of squeeze casting piston. When the hydrogen content is higher than 0.25 mL/100 g for squeeze casting samples

or the hydrogen content is higher than 0.15 mL/100 g for gravity casting samples

so there is a high probability of micro holes in the boundary of remelting zone. Under the same casting conditions

the high hydrogen content is easier to cause micro holes than the low hydrogen content

and under the same hydrogen content

the micro holes in gravity casting piston are more likely to appear than that of squeeze casting piston during remelting.