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FEATURE A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A R C H 2 0 2 2 3 9 yield less distortion of the eccentric bore geometry. Re- gardless, a 50% reduction in distortion was achieved when compared to the currently used processing conditions for Ferrium C64. DANTE simulations have been conducted on various geometries, using various DCGQ recipes, and it has been shown that it is possible to design a DCGQ recipe that com- pletely eliminates the shape change distortion, with only the uniform volumetric size change from the initial to final volume microstructure occurring. Generally, this recipe takes too much time to be practical. However, the process- ing time can be reduced to determine acceptable distor- tion and processing time; the DCGQ recipe used to reduce distortion in the eccentric bore coupon by 50% was exe- cuted in one hour, where the recipe resulting in no shape change of this geometry, determined by DANTE modeling, requires seven hours to complete. CONCLUSIONS The DANTE Controlled Gas Quenching (DCGQ) pro- cess has the potential to handle difficult-to-quench part geometries without the use of expensive press quench tooling and reduce the amount of post-heat treatment pro- cessing required. The work presented here concluded that it is possible to control the temperature of quench gas en- tering a quench vessel, at atmospheric pressure, in order to follow a time-temperature recipe required to control the martensitic transformation rate in high hardenability steel alloys. The prototype unit constructed was able to achieve great control within the temperature range of 400 to 100°C, using varying rates of temperature change. The work fur- ther concluded that for Ferrium C64, the relatively slow transformation rate from austenite to martensite did not alter the microstructure, mechanical properties, or residu- al stress when compared the current standard quenching process. Furthermore, DCGQ was shown to significantly reduce distortion in a difficult-to-quench geometry when compared to HPGQ. Besides having the capability to significantly reduce distortion for difficult-to-quench part geometries, DCGQ has also been shown, through the use of DANTE modeling, to be less sensitive to nonuniform convective cooling con- ditions created by equipment design. The DCGQ process can also result in more dimensionally consistent compo- nents. All of DCGQ’s benefits are a result of controlling the martensitic transformation. By controlling the martensitic transformation throughout the part, it is possible to re- duce the nonuniform cooling effect created by geometry and equipment design, ensuring that the transformation proceeds in a consistent way, part after part. Consistent and predictable distortion allows the part’s pre heat treat- ment configuration to be redesigned such that the post- heat treated shape is within design tolerances and a mini- mal amount of post-heat treatment processing is required. ~HTPro For more information: Justin Sims, senior engineer, DAN- TE Solutions Inc., 7261 Engle Rd. Ste. 105, Cleveland, OH 44130-3479, 440.234.8477 , justin.sims@dante-solutions. com, dantesolutions.com . Acknowledgments The authors wish to acknowledge the U.S. Army Com- bat Capabilities Development Command Aviation & Missile Center (DEVCOM AvMC) for their support of this work. The authors also wish to acknowledge Solar Atmospheres for heat treating the experimental coupons using LPC and HPGQ, Akron Steel Treating for hosting the prototype DCGQ unit and conducting the experiments using DCGQ, and Tensile Testing Metallurgical Laboratory for mechan- ical property testing. 10 Interested in advertising with the ASMHeat Treating Society? Contact Kelly “KJ” Johanns at kelly.johanns@asminternational.org. 7