Vikas Saraf, Sr Director, Engineering And Technology At ATI Forged Products
Digital modeling advances ATI’s capabilities to create next-gen aerospace materials and components by optimizing materials, components and manufacturing processes to deliver location-specific microstructure and properties and enhancing component performance.
The aerospace industry, whether for commercial aviation, defense applications or space launch and exploration, requires complex material alloy systems to meet the needs of such extreme environments. Components, primarily Nickel, Titanium, and Aluminum based, are required to have specific properties, in specific locations.
ATI’s deep understanding of these alloys enables our processing of complicated systems to achieve the right structure, properties and processing to meet the requirements of each application. Through the extensive use of modeling, we achieve right-first-time exponentially faster, eliminating physical waits, using less energy, and without wasting materials.
Metallurgy is the original frontier of micro and nano materials. Modeling supports every step of our integrated processes, giving us a micro, and even nano-level, understanding of what’s happening in the material:
• Melt, including Powder Materials: ensuring chemical homogeneity and microcleanliness
• Billet: producing a uniform microstructure with exactly the right type, size, and distribution of grains;
• Forging: transforming the geometry and structure within tight tolerances making the same part every time;
• Heat treat: combined with forging to ultimately deliver the needed properties, in the right location required for the component;
• Machining: achieving the physical form of the component while preserving the structure on the surface and in the core
ATI uses modeling and artificial intelligence to optimize our physical processes to deliver the required physical, mechanical and microstructural properties required of our components to withstand the extreme environments inherent in wide-ranging aerospace applications: exposure to highly corrosive materials, high loads/stresses and temperatures so high that under normal conditions the materials would start to melt.
The key drivers for performance improvements in the aerospace industry include lower weight, faster flight, increased fuel efficiency, reduced noise and reduced emissions. Advances in materials science helps make these achievements possible. This evolution, pragmatically, occurs in two design spaces – speed and efficiency – with desired outcomes driving development.
• Faster Speed
- Component Life is important but, likely, not a critical constraint
- Components perform in extreme environments, and then recycled
- Dominated by a few extreme mechanical and microstructural properties
• Increased Efficiency
- Component Life cycle cost is a driver
- Components perform predictably, in a controlled environment
- Extreme environments are adjusted to meet Life
For example, space vehicles are mission critical requiring incredible performance capabilities and undergo extreme and variety of mission stress in a short span. Airplane engines and components are expected to go through multiple cycles of rest, thrust and dwell before a planned maintenance cycle.
Component performance in both design spaces requires customized microstructure and properties. As an example, a component utilized in different design spaces and made of the same alloy is manufactured differently. The same basic process is followed, but the conditions vary to meet the requirement.
Figure 1: Integrated Computational Materials and Manufacturing Engineering Approach at ATI.
The production of component-specific customized properties requires research in material characterization, property response through various thermo-mechanical processing, development of predictive modeling tools to perform optimization studies, fine control of the equipment to manufacture the components consistently, and understanding the influence of component design features through sensitivity analysis.
This is possible by using an Integrated Computational Materials and Manufacturing Engineering (ICME) framework for materials, components and manufacturing technologies. Figure 1 shows the ICME framework at ATI. Within the framework, various materials, equipment, component design, process design computational and statistical models are integrated to rapidly develop and deploy optimal products with proper validation to meet the performance targets.
For a specific example, consider designing the manufacturing process of a jet-engine disc to determine the size of secondary gamma prime to balance various mechanical properties. We run a modeling simulation to determine the best physical conditions – and to help determine the likely repeatability of the process. Figure 2 shows the results of a solution-quench heat treat process modeling simulation focused on a specific section of the forging. This allows ATI to optimize the process before the component is made, importantly before resources are invested in producing components.
Figure 2: Results from a modeling optimization technique utilized to customize the solution-quench heat treat process for an aerospace component. Optimized cooling environment was determined and applied to drive the microstructure in the component (a) objective to achieve cooling rate (ACR) within a discreet region of a component, (b) minimize a quantified measure of a structure (secondary gamma prime particle size) known to deliver required mechanical properties, (c) a specific calculated value of the structure is represented by a probability function to provide spatial distribution and uncertainty to our application engineers.
Through this integrated approach, ATI has developed and produced complex material alloy systems, and highly engineered and technologically advanced components, thus, transforming the global aerospace industry. Upfront optimizing during the development of new materials, components and processes and connecting them to the performances in the applied environment, enables engineers and technologists to continue to contribute to our commitment to advancing the aerospace industry.