2 results
Search Results
Now showing 1 - 2 of 2
Article Citation - WoS: 37Citation - Scopus: 40Dynamic strain aging in DP steels at forming relevant strain rates and temperatures(Elsevier Science Sa, 2017) Bayramin, Berkay; Simsir, Caner; Efe, MertMechanical testing of dual phase (DP) steels at low strain rates (10(-3) s(-1)) have shown that they are susceptible to dynamic strain aging (DSA) between 100 degrees C-400 degrees C. During industrial forming processes at intermediate strain rates (1-10(2) s(-1)), the local temperatures may rise to the DSA range due to deformation heating which may disturb the exceptional formability of these steels. In this study, two grades of DP steel (DP590 and DP800) are tested at thermomechanical conditions relevant to forming and the effects of DSA on the formability are established. Test results show that the DSA controls the deformation between 200 degrees C-300 degrees C through serrations in the stress-strain curves of both grades. With increasing strain rates (up to 1 s(-1)) and temperatures, DSA intensifies and results in severe drops in uniform and total ductility with negative strain rate sensitivity, indicating poor formability at these conditions. A detailed analysis of the serrations coupled with dislocation density measurements by x-ray analysis suggests that the serrations can be linked to a periodic microstructural feature.Conference Object Effect of Batch and Continuous Annealing Processes on Crystallographic Texture and Formability of an If Steel(Association for Iron and Steel Technology, AISTECH, 2017) Aldikacti,G.; Baskaya,U.; Davut,K.IF (interstit ial free) steels are used in many applicatio ns, specifically in automotive industry due to their excellent formability. This formability behaviour is directly related to the annealing process, which influences both the crystallographic texture and the related "r value". For annealing, two main routes, namely batch and continuous annealing processes, are used in the production of IF-steels. The present study aims at comparing the same grade of IF steels produced via batch and continuous annealing processes. For this purpose, the texture and microstructure analysis were performed by electron backscatter diffraction (EBSD) technique in a scanning electron microscope (SEM). The formability behaviour of the steel sheet was characterized by determining the hardening curve and yield surface. It has been found that all samples show a strong ND fiber; {111}//ND. On the other hand, the drawability and related "r value" of continuously annealed samples were better than batch annealed ones. This behaviour is explained by the ultra-low carbon content, lower yield strength and equiaxial grain structure. © Copyright 2017 MS&T17®.
