Computational Design of Corrosion Resistant Steels for Structural Applications in Aircraft (SEED Project)

WP-1149

Objective

WP-1149 Project Graphic

Computational Design of Corrosion Resistant Steels

Externally-applied coatings such as chromium, cadmium, and even paints can be difficult to apply and, if damaged in service, can lead to catastrophic failure on highlystressed aircraft components such as landing gear. Most coating techniques were developed before stringent environmental regulations became effective and, therefore, are not environmentally friendly. As a result, significant effort is now underway to develop new coating technologies.

The objective of this program was to design, prototype, and characterize a new corrosion resistant steel that could significantly reduce the Department of Defense’s use of cadmium during the rework, maintenance, and manufacturing of structural steel components for aerospace applications.

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Technical Approach

There were four primary technical tasks within the program. The specific activities within each task resulted from the application of a materials-by-design approach, which integrates processing, structure, property, and performance relations within a multi-level systems structure. Initially, a flow block diagram was generated, and models for the design process were calibrated. An alloy composition and the processing variables were then determined. Next, 300 pounds of the prototype material were acquired and characterized. The prototype showed properties very close to the design objectives, thereby demonstrating the possibility of delivering an entirely new corrosion resistant steel that possesses similar mechanical properties to 300M steel and is compatible with current and emerging aerospace coating processes.

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Results

The first prototype alloy, a martensitic steel, met the primary objectives for ductility and corrosion resistance but was approximately 2 HRC (Rockwell C-Scale Hardness) low in hardness and 15 percent low in strength. Most of this strength deficit was due to an improper heat treatment during the forging of the prototype at the mill, necessitating a subsequent high temperature homogenization treatment leading to undesirable grain growth. Model estimates indicate that with correct forging practices, the alloy design would have been within 5 percent of the desired strength goals. The measured MS (martensite start) temperature of the alloy was 25 degrees below predictions, indicating retained austenite may have been responsible for the remaining 5 percent strength deficit. The second iteration prototypes are currently under evaluation. This FY00 funded SEED project transitioned to a core FY01 New Start project (see WP-1224).

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Benefits

The use of mechanistic computational design technology enables the rapid development of entirely new materials and processes at costs that are orders of magnitude below what is incurred through the historical application of “trial and error” discovery methodology.

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Project Documents

Points of Contact

Principal Investigator

Dr. Charles Kuehmann

QuesTek Innovations LLC

Phone: 847-425-8222

Fax: 847-328-5855

Program Manager

Weapons Systems and Platforms

SERDP and ESTCP

Project Documents

Document Types

  • Fact Sheet - Brief project summary with links to related documents and points of contact.
  • Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
  • Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
  • Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
  • Guidance - Instructional information on technical topics such as protocols and user’s guides.
  • Workshop Report - Summary of workshop discussion and findings.
  • Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
  • Model/Software - Computer programs and applications available for download.
  • Database - Digitally organized collection of data available to search and access.