General Motors is applying third-generation advanced high-strength steel to the new Chevrolet LOVA RV from SAIC-GM, thereby reducing the weight of selected body components by approximately 20%. The recreational vehicle (RV) was launched on 19 November 2015.
The new steel offers a superior balance of strength and ductility as compared to the first generation of high-strength steels. The fuel economy of a vehicle is generally considered to increase by 6 to 8% for every 10% reduction in body weight.
In 2009, GM began encouraging steel manufacturers to produce third-generation advanced high-strength steel with superior formability and tensile strengths of 1,000 MPa and higher for vehicle bodies.
Among all the state-of-art steel-making processes, the GM China Science Lab in Shanghai identified the Quench and Partition (Q&P) process as one of most promising solutions for producing third-generation advanced high-strength steel.cQ&P steel represents a new type of ultrahigh-strength steel with good ductility to improve fuel economy while promoting passenger safety.
With a final microstructure of ferrite (in the case of partial austenitization), martensite, and retained austenite, Q&P steel exhibits an excellent combination of strength and ductility. Through a specially-designed quenching and partitioning treatment, retained austenite can be stabilized in the steel microstructure at room temperature, which significantly improves the formability of steel.
In 2011, GM China Science Lab joined GM’s Pan Asia Technical Automotive Center (PATAC) joint venture, Baosteel and Tongji University to establish an expert team to develop solutions for introducing Q&P steels into GM vehicles.
Research groups within the GM China Science Lab, GM China Advanced Technical Center (ATC), and the GM Warren Technical Center in the United States collaborated on research and development of third-generation advanced high-strength steel. This global development network was instrumental in the successful implementation of the advanced steel technology in GM vehicles.
In the past, nearly 25 years of research and development were required to go from initial steel development concepts to production of the first-generation high-strength steels such as dual-phase steel. Through open innovation, GM and its partners have been able to shorten significantly the concept-to-production process of third generation steels.
GM has also contributed significantly to the application of key technologies by studying materials, microstructures and assessing their performance. Findings from these investigations are now being applied to the development of third-generation 1,200 MPa Q&P steel.
In addition, assessment methods that precisely measure the performance of third-generation advanced high-strength steel, especially in terms of crashworthiness, have been adopted by a number of steelmakers. Technical learnings such as these are being shared worldwide within GM and will be instrumental to future applications of third-generation steels in GM vehicles around the globe.
Louis G. Hector, Jr. and Ron Krupitzer (2014) “The Next Generation of Advanced High Strength Steels – Computation, Product Design and Performance” First-Year Progress Update on the DOE ICME 3GAHSS Project
Li Wang, John G. Speer (2012) “Quenching and Partitioning Steel Heat Treatment” In: ASM Handbook, Vol 4A: Steel Heat Treating Fundamentals and Processes
Li Wang, Weijun Feng (2011) “Development and Application of Q&P Sheet Steels” In: Advanced Steels, Springer