1. Sridhar Seetharaman Carnegie Mellon University Department of Materials Science and Engineering Pittsburgh, PA 15213-3890 Steels for the next generation automobiles Steels for the next generation automobiles DMR-0307188

2. Sridhar Seetharaman Carnegie Mellon University Department of Materials Science and Engineering Pittsburgh, PA 15213-3890 Motivation: As congressional efforts and those of individual states (such as California) in the regulation of CO 2 emissions continue to move forward, it is important for automakers to research various means towards reducing the weight of their automotive bodies to increase fuel efficiency. Ultra-high strength TRIP steels, help reduce weight by being stronger. Oxide scale formation during processing hinders coating and thus is an impediment to producing exposed automotive parts from TRIP steels. Objectives: In this project we study the fundamentals of how oxides evolve on the surface of TRIP steel samples in order to gin an insight into how to optimize processing of coated TRIP products. This a collaborative project between Carnegie Mellon and two PA industrial research labs, US-Steel Technical Center and ISG-Steel Homer Research Laboratory. Introduction

3. Sridhar Seetharaman Carnegie Mellon University Department of Materials Science and Engineering Pittsburgh, PA 15213-3890 Technical Approach: The research involves characterizing TRIP surfaces in terms of micro-structural features and relating these to the type and growth rate of oxide during annealing and hot-rolling. A unique high- temperature confocal scanning laser microscope is being employed to visualize the oxide growth and a TGA-DTA system with dew point controlled is used to quantify the oxide growth. Figure 1: The High Temperature Confocal Scanning Microscope Educational Aspects: Graduate students involved will spend parts of their summers at the industrial sites in order to utilize facilities and to gain an insight into how their research in relevant for the manufacturing of automotive steel parts. Intellectual Merits

4. Sridhar Seetharaman Carnegie Mellon University Department of Materials Science and Engineering Pittsburgh, PA 15213-3890 Results to date: Surfaces of cast TRIP samples were characterized in terms of grain size distribution and compared to the locations were oxide was shown to evolve in the CSLM. Figure 2 below shows results from etching and Figure 3 shows the successive oxide evolution. Figure 3: Above are images showing the progression of oxide (black) across the surface of the TRIP steel (white) at 400 o C. Figure 4: Surface of cast sample etched with 2% nital.

5. Sridhar Seetharaman Carnegie Mellon University Department of Materials Science and Engineering Pittsburgh, PA 15213-3890 Broader Impacts Industry and society: The US steel industry faces stiff competition from contries with low labor costs and less stringent environmental regulations. To maintain a competitive edge, advantages in process control and product quality have to be maintained. This project aims to study fundamental issues that are key for allowing for continuous manufacturing of ultrahigh strength steels for cars. The knowledge gained will eventually aid in the production of light weight cars that consume less fuel and produce less emission. Education: Materials graduate education has traditionally focused on processing, structure and properties. This project will introduce the aspect of performance, that will educate future engineers in how a technical advance impacts an process.