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Spring 2009 Seminar Series
Wednesday, May 27, at 3:30 p.m.
Room 264 MacQuigg Labs
Emmanuel De Moor
Advanced Steel Processing and Products Research Center
Colorado School of Mines
Assessment of Quench & Partitioning as a Fundamentally New Way of Producing Advanced High Strength Martensitic Steel Grades with Improved Ductility
Abstract
Over the last two decades a significant research effort has been put in the development of Advanced High Strength Steel grades (AHSS). This research was mainly driven by the automotive industry aiming at reducing weight in order to increase gas mileage, improving passive safety and competing with light-weight materials such as Al and Mg alloys. Quench and Partitioning (Q&P) has recently been proposed as a fundamentally new approach of producing advanced high strength steel (AHSS) microstructures consisting of martensite and carbon stabilized retained austenite. The heat treatment consists of a two-step process. After soaking in the intercritical region or above the A3 temperature, the steel is quenched, avoiding bainite formation, to a pre-determined temperature QT in the Ms-Mf region. A partially martensitic, partially austenitic microstructure is present at this stage. In a second, so-called partitioning step, the steel is either maintained at the QT or brought to a higher temperature PT. The aim of the latter step is to carbon stabilize the austenite present at the QT by carbon depletion of the martensite and transport to the austenite. After final quenching to room temperature, a martensitic microstructure containing significant volume fractions of carbon stabilized retained austenite is obtained.
A variety of compositions was tested in present work with alloying modifications mainly involving Si, Al, and Mo. The effect of these alloying elements on the retained austenite fractions obtained following Q&P was assessed and studied by Differential Scanning Calorimetry (DSC) and dilatometry. Mechanical properties were assessed by tensile and hole expansion testing.
Bio
Emmanuel De Moor received his MS and PhD degree from the university of Ghent, Belgium where he was involved in the Transformation Induced Plasticity (TRIP) steel research group at the Laboratory for Iron and Steelmaking (lism). Currently he is a post-doctoral research associate with the Advanced Steel Processing and Products Research Center (ASPPRC), an industry/university cooperative research center at the Colorado School of Mines. His current research involves sheet, bar, wire and plate grades.
Please join our speaker for light refreshments in 479 Watts Hall following the talk.
