Evaluation of Ultra-High Gas Pressure Quenching During HIP

Hot isostatic pressing or HIP has been used for diffusion bonding, casting densification, and powder consolidation.  Continued advances in HIP equipment design have allowed increasingly rapid cooling recently reaching a point where true high-pressure gas quenching is now possible within the HIP unit. This capability allows the integration of a heat treat process within a HIP cycle.  Within the heat treat industry, high pressure gas quenching has been an area of significant development however, where typical high pressure gas quenching equipment offers quench pressures up to 15 or 20 bar, common HIP pressures are 1000 bar or higher.  Thus, the ability to quench from HIP pressures appears to offer heat treat options not previously available.  This paper examines ultra-high pressure gas quenching (from 1000 bar) within the HIP unit from a heat treating point of view using the analysis techniques that others have employed to characterize conventional gas quenching.