|
Metallurgical processing of aerospace alloys
Aerospace alloys are subject to stringent quality requirements such as uniformity of composition and
microstructure, and absence of inclusions and segregation defects. Therefore, the processes for making alloy ingots that are used for manufacturing  aeroengine parts, are very capital intensive and costly to
operate. Some of the commonly used processes are as follows:
- Cold Hearth Refining
- Electron Beam Melting (EBM)
- Plasma Arc Remelting (PAM)
- Remelting Processes for Ingot Production
- Electroslag Remelting (ESR)
- Vacuum Arc Remelting (VAR)
- Electron Beam Melting
These processes are governed by the underlying fluid flow, heat transfer, phase change, and electromagnetic
phenomena. Therefore, the process performance and the quality of the final material produced are determined by a complex interaction of the process parameters.
Computational Fluid Dynamics analysis provides detailed information about the flow and temperature fields, the pool shape, the mushy region, and macrosegregation.
This information minimizes the expensive trial-and-error based process development and provides the following benefits:
- Insights into and basic understanding of the process physics that is critical in creating ideas for process modifications
- Process optimization based on the quantitative information about the effect of process parameters on process performance
- Evaluation of new processes and modifications to existing processes
- Substantial savings in capital investments and operating costs
At Innovative Research, we have developed specialized programs for accurate and efficient modeling of the Cold
Hearth Refining, and Remelting/Ingot Casting processes. Use of these models by leading engine manufacturers and alloy producers has already resulted in significant
improvements of existing processes and the development of new processes.
Cold Hearth Refining Processes
At Innovative Research, we have developed customized programs for the modeling of Cold Hearth Refining using Electron Beam Melting (EBM) and Plasma Arc Melting (PAM) of Titanium alloys.
- The features of the specialized programs are as follows:
- Three-dimensional calculation under steady and unsteady conditions
- Specification of the geometry and the operating/boundary conditions in a Graphical User Interface (GUI)
- Detailed prediction of the flow and temperature fields, phase change, pool shape, and the mushy region
- Radiative heat losses from crucible and metal surfaces
- Prediction of the motion, dissolution, and entrapment of inclusions
- Flexibility and adaptability to incorporate models for variants of the standard processes
The EBM and PAM models have been extensively validated using data from production
furnaces. These models are being actively used by process engineers and researchers at leading alloy producers and engine manufacturers for process improvement and optimization.
Remelting and Ingot Casting
At Innovative Research, we have developed customized programs for efficient and
accurate modeling of Ingot Casting during Remelting processes for aerospace alloys (e.g. Nickel and Titanium alloys). Separate modules have been developed for
Electroslag Remelting (ESR), Vacuum Arc Remelting (VAR), and Electron Beam Remelting (EBM). The features of the specialized programs are as follows:
- Efficient calculation using two-dimensional axisymmetric conditions
- Specification of the geometry and the operating/boundary conditions in a Graphical User Interface (GUI)
- Detailed prediction of the flow and temperature fields, pool shape, and the mushy region
- Accurate modeling of the mold heat transfer in presence of shrinkage
- Current distribution (VAR, ESR) and Joule heating in the slag (ESR)
- Use of a single domain for slag and metal regions in ESR
- Flexibility and adaptability to incorporate models for variants of the standard processes
Use of these models in the analysis of industrial VAR, ESR, and EB ingot casting
processes provides a scientific approach for process development. Indeed, such use at leading engine manufacturers and alloy producers has resulted in significant cost
savings relative to conventional trial-and-error based approach for new process design and operation.
|
