The Influence of Microstructure on the Mechanical Behaviour of Dual Phase Steels
The transportation industry, in particular the automotive industry, is facing a number of challenges that include a continuous increase on the requirements defined by legislation on efficiency, fuel consumption, gas emissions and safety. These challenges can be addressed by the use of stronger materials to produce thinner components that contributes for weight reduction of automobiles and improvements of aspects related to the safety. Among high-strength materials, the dual phase (DP) steels combine high strength with an adequate ductility and formability, good hardening behaviour and fracture toughness. This class of steels has a microstructure composed by hard martensite particles dispersed in a soft ferritic matrix. In this chapter, a study is presented on the mechanical and microstructural behaviour of DP steels sheets with different amounts of martensite. The mechanical behaviour was characterized by tensile tests along different sheet orientations. The mechanical behaviour exhibited by material during these tests was also analyzed in terms of dislocation microstructure and crystallographic texture evolutions. It is shown that the anisotropic behaviour for monotonic tests is due and related to their initial crystallographic texture, while corresponding relation and prediction is successfully performed by a VPSC (viscoplastic self-consistent) model.
KeywordsDual phase steels Sheet metal forming Bulge test
The authors would like to acknowledge the support of this work by FEDER funds through the Operational Program for Competitiveness Factors (COMPETE) and by national funds through the FCT (Foundation for Science and Technology) through the projects PTDC/EMS-TEC/2404/2012, POCI-01-0145-FEDER-016876 and PTDC/EMS-TEC/6400/2014.
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