Characterization of Macroscopic Local Deformation Behavior of Thermo-Mechanically Graded High Strength Aluminum and Steel Alloys

EasyChair Preprint 9166

Abstract

In this study, the local deformation behavior of the transition zone of thermo-mechanically graded boron steel 22MnB5 and high strength aluminum alloy AA7075 is investigated using an in-situ approach. For this aim, forming tool segments are differentially heated in order to obtain locally tailored microstructures and dissimilar mechanical properties based on the process-induced microstructural phenomena. Material strength distribution is examined by Vickers hardness measurements after thermo-mechanical processing. Tracking of the material- and geometry-dependent local deformation behavior of the resulted transition zone is performed by tensile tests coupled with digital image correlation technique. The experimental results reveal within the transition zone a characteristic reversed S-shape hardness distribution, similar to a sigmoidal curve. The local deformation characterization indicates the occurrence of plastic deformation mainly in the soft zones at the heated forming tools segments, while the harder zones at the cooled tool segments exhibit only an elastic deformation and remain undeformed. By comparing the macroscopic local deformation evolution shortly before failure, absolute strain values up to evon Mises = 0.62 and evon Mises = 0.28 and a distinct reduction in the area are obtained for 22MnB5 and AA7075, respectively. The occurred plastic strain pattern show the formation of shear bands after a homogenous localization at the necking point.

Keyphrases: Aluminium, Differential cooling, Functional gradation, Macroscopic local deformation, steel

@booklet{EasyChair:9166,
  author    = {Emad Scharifi and Sebastian Hirte and Steffen Lotz and Michael Mlynek and Ursula Weidig and Agim Ademaj and Kurt Steinhoff},
  title     = {Characterization of Macroscopic Local Deformation Behavior of Thermo-Mechanically Graded High Strength Aluminum and Steel Alloys},
  howpublished = {EasyChair Preprint 9166},
  year      = {EasyChair, 2022}}