However, total reductions are another matter. You have the pot die (used for most hollow blanks for rings). Assuming you are starting with a cast ingot/billet, the reduction is a function of the backward extrusion reduction followed by the subsequent reduction you described. However, the most important reductions are those obtained in final forging, because that is what controls the grain size of most steels.
The grain size reduces upon annealing if the final forging temperatures are proper for the alloy. For example, overheating can occur at only 2,200°F for a low-alloy steel if there is little or no reduction. For austenitic stainless, final grain size is controlled almost entirely by the final forging reduction.
The reduction requirements for cast material are important to consider, because any remaining cast structures in the resulting billet can compromise the properties and leave residual porosity. However, when starting with press-forged billets (ahead of your ring forging), the reductions should have been sufficient by the method you described.
For more than 40 years H. James Henning held key technical positions in the forging industry, including as director of technology for the Forging Industry Association, and as president of Henning Education Services, a Columbus, OH, firm specializing in customized education and training in forging technologies.
Guidelines and recommendations offered in this column are based on information believed to be reliable and are supplied in good faith but without guarantee. Operational conditions that exist in individual plants and facilities vary widely. Users of this information should adapt it, and always exercise independent discretion in establishing plant or facility operating practice.