OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software;Advanced Materials OBJECTIVE: Develop and validate advanced modeling and simulation tools for predicting the microstructural and material property response to raw material melt and heat treatment processing variables of aerospace gear and rolling element bearing steels. DESCRIPTION: High-performance gear and bearing steel alloys such as X-53, Pyrowear53 (P53), and Pyrowear675 (P675) can be susceptible to several types of material defects such as inclusions, sub-optimal microstructures and undesirable carbide morphologies and chemistries due to the raw material melt and/or heat treatment processes (i.e., carburization). There have been multiple instances where such defects have escaped non-destructive inspection (NDI) quality assurance processes currently in place to preclude these from service, resulting in poor component reliability and catastrophic failure leading to multiple safety mishaps. Traditional methods to address the issue often involve large scale empirical testing to determine root cause and corrective action, which consumes large amounts of resources and time, prohibitive in the current state of warfighter operational tempo and supply chain challenges. Computer modeling and simulation (M&S) is a powerful method that can be applied to explore critical material process variables in a digital space, potentially allowing rapid iteration and ability to reduce the amount of empirical testing required to deliver a robust material solution. Although such M&S tools already exist, there has not been a dedicated effort to apply these to the subject steel alloys of interest and identified above. This SBIR topic is aimed at leveraging existing M&S tools available from small business entities to help address the forgoing material processing issues described above. The end-goal is to enable original equipment manufacturers (OEMs), suppliers, and end users to perform processing simulations, microstructure modeling, and material property predictions to computationally investigate material issues and optimize gear and bearing material performance for critical aerospace applications. There is also potential to leverage across to other alloys once the benefit is realized. Emphasis is on case carburized gear and bearing steel alloys such as Pyrowear675 (P675), X-53, and Pyrowear53 (P53). These alloys are currently used in safety critical components and sub-assemblies including aircraft gearboxes, transmissions and propulsion systems on multiple naval aviation platforms including the F-35, V-22, CH-53K, and H-1. PHASE I: For a Direct to Phase II topic, the Government expects that the small business would have accomplished the following in a Phase I-type effort and developed a concept for a workable prototype or design to address, at a minimum, the basic requirements of the stated objective above. The below actions would be required to satisfy the requirements of Phase I: Developed a physics-based computational model and simulation tool capable of performing heat treatment processing simulations, microstructural modeling, and resulting material property predictions. Demonstrated the feasibility of the existing M&S tool by validating simulated predictions with microstructural evaluation of applicable material coupons and specimen/component testing (if available). Examples of validation include, but are not limited to, residual stress measurement and case depth, dimensional/strain measurement through heat treat process, microstructural phase composition determination. FEASIBILITY DOCUMENTATION: Offerors interested in participating in Direct to Phase II must include in their response to this topic Phase I feasibility documentation that substantiates the scientific and technical merit and Phase I feasibility described in Phase I above has been met (i.e., the small business must have performed Phase I-type research and development related to the topic NOT solely based on work performed under prior or ongoing federally funded SBIR/STTR work) and describe the potential commercialization applications. The documentation provided must validate that the proposer has completed development of technology as stated in Phase I above. PHASE II: Develop a computational model of one of the materials of interest above as a baseline, with potential expansion to other materials of interest. Explore variables in the digital space that can affect material microstructure, performance, hardenability, and overall fatigue properties. The software tool must be capable of modeling material microstructure in raw material form, account for variations in alloy element compositions including inclusion content and phase transformation, computationally investigate material response to post processing operations (i.e., forging, heat treat, and carburization operations). Anticipated tasks include the following: 1. Coordinate with a supply chain in a representative bearing or gear application to determine detailed material properties and refine modeling and simulation changes in properties that occur through raw material ingot formation, forging, and subsequent heat treatment operations prior to final machining of a component. 2. Investigate carburization response of selected material to heat treat variable processing inputs such as coarsening effects of carbides molybdenum carbide (MoC), chromium carbide (CrC), and other relevant carbides; grain growth, diffusion, and precipitation during carburization equilibrium microstructure and homogenization processes; evaluation of variable processing history to evaluate whether MoC dispersion or alternate microstructural features more significantly impact carburization response and determine methods of elimination. 3. Develop and/or upgrade of an existing modeling tool capable of predicting carbide formation including carbide size, distribution, and location within the microstructure. The modeling tool should be able to establish mitigation strategies for precipitation in areas other than prior austenite grain boundaries as an output. 4. Validate software predictions thru subscale coupon and component testing. PHASE III DUAL USE APPLICATIONS: Integrate the Phase II developed M&S tool to OEM and suppliers of steel alloy gears and bearings manufacturing process, to optimize alloy melt and heat treatment processes to ultimately provide the Navy with microstructurally robust steel alloy components. Potential dual use applications include any aerospace/automotive/marine/industrial applications that require high performance alloys (e.g., powertrain transmissions systems, turbine engine subcomponents, and gas pipelines). REFERENCES: 1. Churyumov, A.Y. and Pozdniakov, A.V. Simulation of microstructure evolution in metal materials under hot plastic deformation and heat treatment. Physics of Metals and Metallography. 121, 2020, pp. 1064-1086. https://doi.org/10.1134/S0031918X20110034 2. Simsir, C. Modeling and simulation of steel heat treatment prediction of microstructure, distortion, residual stresses, and cracking. ASM Handbook 4B, Chapter: Modeling and Simulation of Steel Heat, September 2014, pp.409-466. https://www.researchgate.net/publication/269984971_Modeling_and_Simulation_of_Steel_Heat_Treatment_Prediction_of_Microstructure_Distortion_Residual_Stresses_and_Cracking KEYWORDS: Inclusions; Carbide Networks; Steel Alloys; Modeling and Simulation; Heat Treatment Modeling; Gears and Bearings
