Materials Design project: High Strength Steels
Project leader: Fei Huyan, Swerim
Center partners: SSAB EMEA Oxelösund and Borlänge, Uddeholms, Sandvik Material Technology, Ovako Sweden, Thermo-Calc Software, QuesTek Europe
KTH PhD students, Postdoctoral researchers or researchers: Joshua Kumpati, Annika Borgenstam, Peter Hedström, Manon Bonvalet Rolland.
QTEAB researchers: Jiayi Yan
By designing steels with significantly higher strength and toughness than available on the market today, constructions and vehicles can become lighter because less material will be needed. Hence, lowering the materials consumption means that less material is produced and consequently CO2 emission are reduced. Furthermore, lighter vehicles will clearly also reduced emissions. Increasing strength however, represents only one dimension of the challenge of designing advanced high strength steels. Such material must also have sufficient combinations of formability, fracture toughness, and residual ductility to be useful in structural and vehicle applications. Additional effects are e.g. improved safety of vehicles since residual ductility of steels is critical for energy absorption in a crash.
There are several possibilities to reach the goal and one of the most potent strengthening mechanisms is precipitation hardening. Other important mechanisms are the TRIP (Transformation Induced Plasticity) and TWIP (Twinned Induced Plasticity) effects and others are to be explored. From a process-structure perspective we already have developed many of the models (creators) needed e.g. for predicting the stacking fault energy, predicting the martensite and bainite start temperatures, phase-field model for the martensite transformation, a model for the formation and growth of bainite, and models for precipitation simulations (TC-PRISMA). These models probably need to be refined or further developed but much of the focus in this project will be on the performance-properties-structure relation, and models (translators) for coupling properties and structure. One challenge will be the coupling of phase field simulations of the structure with gradient plasticity simulations.