Olson directs the Steel Research Group (SRG), a large-scale multi-institutional research program centered at Northwestern University's Materials Research Center. Over 30 investigators participate, including researchers at Harvard, Brown, MIT and Illinois Institute of Technology, several Department of Defense laboratories and a number of steel companies. "It was conceived in 1985," says Olson, "as a six-year program to develop the fundamental models and database by which you could actually design alloys on the computer."
The work progressed on schedule, and in 1991 Olson's group at Northwestern designed a new steel for bearings in the main engine turbo pumps of the space shuttle. This prototype ultrahigh-strength bearing steel withstands pressure, corrosion and high temperature beyond any previous steel. With this success under its belt, SRG kept going, and it is now applying the same design methods to develop advanced steel for other weight-critical applications such as helicopters, high-performance race cars and naval aircraft landing gear. "Steel is heavy," notes Olson, "but sometimes it's the only thing that can do the job. If you can push the strength up so you use less of it, you can save a lot of weight."
The lower panels are difference plots --showing how the electron distribution changes when phosphorus is in the steel compared to only iron. Electron gain is shown in pink (greatest), red, yellow and green, and electron loss is purple and blue (more negative). These plots show that phosphorus bonds much more strongly with the iron atom below it at the free surface (large pink area) than it does at the grain boundary. "Phosphorous at the free surface has lowered energy," explains Olson, "which means that phosphorus at the grain boundary reduces the work of fracture-promoting embrittlement of the steel."
Researcher: Gregory B. Olson, Northwestern University
Hardware: CRAY C90
Software: FLAPW (full-potential linearized augmented plane wave method)
Keywords: materials research, ultrahigh-strength bearing steel, iron, impurities, defects, stress, corrosion, martensitic transformation, crystal structure, engineering science, quantum theory, electron distribution, free surface, grain boundary, Steel Research Group (SRG).
Related Material on the Web:
Projects in Scientific Computing, PSC's annual research report.
References, Acknowledgements & Credits