During hot forging, the temperature reaches above the recrystallization point of the formed metal. As the step of plastically deforming the metal above the recrystallization temperature, these high temperatures are required in order to avoid strain hardening during deformation. This process typically involves heating the metal (above its recrystallization point) and then comminuting it into a mold that can also be heated as needed. Because the metal is hot, it is easy to “move” and enables manufacturers to make more complex shapes than cold forging.

For superalloys, which have low malleability, processes such as isothermal forging (deformation in a controlled atmosphere) are used to avoid oxidation. Isothermal forging, also known as hot forging, is a thermal processing process that keeps a workpiece at its maximum temperature throughout the forming process.

Maintaining this temperature is done by heating the mold – it will be at an elevated or slightly lower temperature of the workpiece. The force applied by the mold forms the workpiece, and because the mold is also at an elevated temperature, the cooling of the workpiece between the mold working interfaces is eliminated. This in turn leads to an improvement in the flow properties of the metal (work piece).

Qianhao has the ability to provide carbon steel and alloy steel forgings made by open-die or closed-die forging process.

Open-die forging involves the shaping of heated metal parts between a top die attached to a ram and a bottom die attached to a hammer, anvil or bolster. In open-die forging, the dies do not enclose the workpiece, allowing it to flow except where contacted by the dies.

Closed die forging involves two or more dies that contain a precut profile of the desired component. The heated raw material is placed at the bottom of the die. The dies then move towards each other until the raw material is formed into its required shape and size.

Open die forging is the best choice when large/long components of the material, with high exacting internal conditions (homogeneity), are required. It also suitable for small quantity orders because of low/no investment cost. Compared to the open die forging, the close die forging can achieve more complex geometries, very much close to the dimensions of the finished component. It is used to manufacture series production as this is particularly convenient to absorb the costs the dies. It allows furthermore to use reduced over-dimensions, feature which allows cost savings on input weights as well as on final machining due to less material to remove.

Forging is a favorable and effective manufacturing process. Each time the metal is beaten, impurities are eliminated and the grains becomes finer, the structure becomes more refined and regular and the metal is transformed into a material that is both flexible and strong. Thus forged parts can achieve high degree of strength and flexibility and stand up to the harshest natural environments.