(Dr. David McDowell, advisor)

"TRIP Steel Behavior"

Abstract

To address low thickness sheet manufacture, several studies are underway. In addition to microstructure control during successive forming operations, another possible way is the development of new steels with high ductility and strength. This research project deals with the second alternative, using the TRIP effect in steels (TRansformation Induced Plasticity). This new kind of steel has very interesting properties such as a coupling between high fracture ductility (30-50%) and strength (800-1300 MPa).

Inelastic anisotropy is used in forming processes to improve drawing of materials; it results from crystallographic texture. Deformation-induced texture comes from the lattice rotation associated with plastic slip and kinematic boundary conditions related to intergranular constraints. These attractive mechanical properties are due to an additional plastic strain (transformation plasticity) due to the transformation from austenite to martensite, beyond the classical plastic strain of steels. For a better understanding of these mechanisms, experiments on the evolution of texture during the transformation and on transformation plasticity will be presented.