The metal forming method includes deforming a member to be formed (2) that includes a second metal and that has been heated and bringing the member into contact with a member to be bonded (3) that includes a first metal and that has been heated, in which the temperature of the member to be bonded (3) is a temperature at which a liquid phase percentage in the member to be bonded (3) is from 5 to 35%.

The metal forming method includes deforming a member to be formed (2) that includes a second metal and that has been heated and bringing the member into contact with a member to be bonded (3) that includes a first metal and that has been heated, in which the temperature of the member to be bonded (3) is a temperature at which a liquid phase percentage in the member to be bonded (3) is from 5 to 35%.

A method is used for manufacturing a shell assembly which includes a metallic shell and a plastic material embedded into the metallic shell. The metallic shell has an outer surface provided with at least one slot. The at least one slot of the metallic shell is provided with a plurality of through holes. The plastic material is injected into the metallic shell, flows through the through holes of the metallic shell, and flows into and out of the at least one slot of the metallic shell during an injection molding process. Thus, the plastic material is embedded in the metallic shell so that the metallic shell and the plastic material are formed integrally.