FEATURE ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 59 come with associated high costs and explosion hazards, respectively, leaving nitrogen as the most practical choice of quenching gas for this discussion. Note that 4D HPGQ, at just 9 bar of N2 quenching gas, has capabilities that fall into the fast oil quenching range. 4D HPGQ improves the quenching process with a focus on reducing distortion. Distortion reduction is achieved mainly from the use of a high-pressure gas quenching system installed in the quenching/unloading chamber (Fig. 3). The 4D HPGQ quenching platform uses a proprietary cooling manifold and chamber (Fig. 4) arrangement that surrounds the part during the quenching process. This approach ensures that there is a uniform flow of cooling gas across the part geometry (top, bottom, and side). Top, bottom, and side quenching is referred to as “3D” cooling. To achieve the “4th dimension” when quenching, the support table rotates the component inside the cooling manifold while the N2 cooling gas flows over the part. Tying the 3D quenching approach with part rotation results in 4D quenching, which has the ability to further enhance quench uniformity. 4D HPGQ also allows for the best possible quench uniformity. Current 4D quench designs allow for up to 10 bar abs. quenching pressure, while as shown previously in Fig. 2, 4D HPGQ is comparable to that of oil quenching without the use of helium. Also, and most importantly, because the cooling nozzles can be adjusted to fit the component’s precise size and geometry, quenching can be fully optimized, and distortion significantly reduced. In addition to the mentioned features, the parameters shown in Table 1 are adjustable and can be varied in their combination. To further illustrate the uniform quenching capability of 4D HPGQ, the entire quench process can be recorded via a small camera in the quenching chamber. As seen in snapshots from the video (Fig. 5), quenching uniformity is very even and rapid. In this example, the part is cooled from a red hot color (1550°F) to a black color (~930°F) in 9 seconds. DISTORTION REDUCTION This section reviews data from three examples. In example 1, the 4D HPGQ process was completed on a Fig. 2 — Quench speed relationship between 4D HPGQ, batch HPGQ, and oil. Fig. 3 — A 4D HPGQ unloading chamber. Fig. 4 — Illustration of 4D HPGQ. TABLE 1 — 4D HPGQ CHAMBER, ADJUSTABLE FEATURES Feature Description Quench pressure 1 to 10 bar abs. gas pressure Gas velocity Cooling blower RPM control Table rotation ON or OFF with RPM and directional adjustment Table oscillation Angle adjustment Time dependent gas flow Controlled via time in seconds 11
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