Computational Design of Corrosion Resistant Steels for Structural Applications in Aircraft
Abstract
A secondary hardening stainless steel has been designed using computational materials design methods with the goal to provide a mechanical equivalent to 300M that eliminates the requirement for cadmium coating, and with it eliminates the primary failure mechanisms for today's landing gear. The complete design and testing process took approximately 6 months and resulted in a single composition optimized to the diverse performance requirements of this application. The result is an alloy designed with several features to ensure a strong, tough, corrosion-resistant material. The alloy, a high Co-Ni-Cr, M2C strengthened martensitic steel, met the primary objectives for ductility and corrosion resistance but was approximately 2 HRC low in hardness (15% low in strength). Most of this strength deficit was due to an improper heat treatment during the forgoing of the prototype at the mill, necessitating a subsequent high temperature homogenization treatment that led to undesirable grain growth. Model estimates indicate that with correct forging practices the alloy design would have been within 5% of the designed strength goals. The measured M(sub s) temperature of the alloy was 25 deg C below predictions, indicating retained austenite may have caused the remaining 5% strength deficit. Characterization studies of the alloy prototype were also completed to confirm and fine tune the accuracy of the models and to make additional modeling projections. A second design iteration will be completed, incorporating adjustments to the model and proper forging practice, and prototype material will be produced to demonstrate the performance goals of this program.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 28, 2000
- Accession Number
- ADA391111
Entities
People
- Charles J. Kuehmann