On the Benefits of High Pressure Heat Treatment Additively Manufactured CoCr

Hot Isostatic Pressing (HIP) has traditionally been added to castings in order to heal gross
defects from the casting processes. As companies transition castings to Additively
Manufactured components, HIP has continued to be specified to ensure low component
porosity. Typical HIP + heat treat standards, for example AMS 5643, were built for
conventional materials; when applied to AM parts, the result is less than optimum
properties as the microstructure of AM parts differs significantly from that of the legacy
manufacturing processes. It has been known that combining key heat treatment processes
with Hot Isostatic Pressing by utilizing fast cooling rates can benefit static properties as
well as improve turn-around time for HIP processing. Argon pressures up to 30ksi with
cooling rates above 300F per minute are now available in production sized HIP systems
to design ideal HIP cycles for high pressure heat treatment. This study will investigate
designed High-Pressure Heat Treatment cycles to consider mechanical performance and
lead time benefits as compared with traditional HIP then heat treatment processing. The
combined cycle thermal processes not only reduce the time at elevated temperature by
30% - 60%, with commensurate reductions in coarsening and grain growth, but it also
reduces the overall variability in the thermal post-processing, which will reduce variability
in the final properties.