We usually say the strength of products will be increased after closed die forging, as the steel billet is shaped during the forging process, its internal grain deforms to follow the general shape of the part. As a result, the grain is continuous throughout the part, giving rise to a piece with improved strength characteristics. Higher strength will help to increase the working performance of products, thus to longer the serving time. That is why closed die forging is always applied in most applications. http://www.kfbcasting.com/forging/die-forging/