Forging processes include various steps to attain favorable material properties such as heat treatment, rapid quench, cold work stress relieving, and artificial aging. These steps, however, also contribute to bulk residual stress. Excessive bulk residual stresses cause a wide of problems, including part distortion during machining and in use, reduced crack initiation life, increased crack growth rates, and an overall reduction in part life. This paper summarizes recent work aimed at measurement-based assessment of bulk residual stresses in cold-compressed aluminum die forgings. The results show that forging process induced residual stress is a repeatable phenomenon with RMS repeatability less than 5% of yield.

PremoMet, a cobalt-free alloy, is engineered for high strength and toughness after quenching and tempering, positioning it as a potential replacement for AISI 4140 and AISI 8630 in gear and flange production, where improved fatigue life is anticipated. Utilizing open-die forging and ring-rolling for component fabrication, optimal properties are attained through meticulous microstructure control, with heat treatment being crucial. Representative seamless rings, produced under standard industrial conditions, were segmented and subjected to varying quenching and tempering regimens to assess microstructural evolution and resulting mechanical properties. This study presents tensile, hardness, and toughness data, complemented by scanning electron microscopy (SEM) for detailed microstructural analysis.

A forging company developed a quench system for the heat treatment of large-scale open-die forgings used in power generation, nuclear, and subsea oil and gas applications, accommodating weights of up to 25 tons. To optimize the uniformity and intensity of quenchant flow and heat transfer rates, a partner engineering firm utilized computational fluid dynamics (CFD) to analyze the flow and mixing generated by the agitation systems. An optimized tank geometry, flow capacity, agitation vectors, and mechanical systems were developed through an iterative CFD design approach, demonstrating significant performance improvements over the original design. Physical trials confirmed enhancements in the magnitude, uniformity, and repeatability of quenchant flow and heat transfer rates. This presentation provides an overview of the CFD design process, key CFD findings, and quenching trial data.