February 2022 Volume 4

FORGING RESEARCH

A case study of a Ground Engaging Tool (GET) Cast Preform was proposed to promote an easier transition into industry by providing a specific example of successfully improving a casting with forging. GETs are used in the mining industry for excavation and are typically produced as castings. A preform design was developed by the University of Alabama using DEFORMmodeling to determine how much additional material should be added to the tip of the casting for sufficient strain during closed die forging to the final part dimensions. The design was based on the expected effect of material flow during forging to provide enhanced properties in the critical area near the tip of the part that sees the most wear in service. The target strain in this section is based on the prior work, which demonstrated improvement in elongations with reduction ratios of at least 1.5 to 1 ratio. The preform went through several iterations for the best potential design with respect to the forging process in collaboration with Clifford Jacobs, the company completing the forging. Once this shape was confirmed, additional review was conducted to include the lifting hook on the top of the part to examine the effect of leaving cast features on the preform geometry.

This complicates the forging process but provides the opportunity to produce geometry that is not available for a typical forging. It was also of interest to preserve the open geometry where the GET part is seated on the bucket, or digging end, of the mining equipment. Comparison of the mechanical properties for two different alloys between the as-cast parts and the preform parts after forging confirmed that the forging process has benefit to the material properties due to the closing of microporosity, which forms during solidification. The preform parts showed an increase in tensile ductility properties (elongation and reduction in area) near the part tip where strain was induced during forging. Additionally, the cast features including the lifting hook and internal geometry of the parts were successfully maintained and unaffected by the forging process. It can be concluded that forging a cast shape with increased material in critical areas improves properties when compared with the as-cast part. This proves the benefit of the added forging step for castings requiring enhanced properties in critical areas and provided an experimental setup for successful completion in an industrial setting.

Figure 3: Side by side comparison of the original casting geometry and the preform geometry. The preform shape is thicker and shorter than the original shape. After forging, the original casting and forging have the same dimensions.

FIA MAGAZINE | FEBRUARY 2022 70