Article

Metallurgical and Materials Transactions A

, Volume 40, Issue 2, pp 342-353

First online:

Cyclic Deformation of Advanced High-Strength Steels: Mechanical Behavior and Microstructural Analysis

  • Timothy B. HilditchAffiliated withCentre for Material and Fibre Innovation, Deakin University Email author 
  • , Ilana B. TimokhinaAffiliated withCentre for Material and Fibre Innovation, Deakin University
  • , Leigh T. RobertsonAffiliated withCentre for Material and Fibre Innovation, Deakin University
  • , Elena V. PerelomaAffiliated withSchool of Mechanical, Materials and Mechatronic Engineering, University of Wollongong
  • , Peter D. HodgsonAffiliated withCentre for Material and Fibre Innovation, Deakin University

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Abstract

The fatigue properties of multiphase steels are an important consideration in the automotive industry. The different microstructural phases present in these steels can influence the strain life and cyclic stabilized strength of the material due to the way in which these phases accommodate the applied cyclic strain. Fully reversed strain-controlled low-cycle fatigue tests have been used to determine the mechanical fatigue performance of a dual-phase (DP) 590 and transformation-induced plasticity (TRIP) 780 steel, with transmission electron microscopy (TEM) used to examine the deformed microstructures. It is shown that the higher strain life and cyclic stabilized strength of the TRIP steel can be attributed to an increased yield strength. Despite the presence of significant levels of retained austenite in the TRIP steel, both steels exhibited similar cyclic softening behavior at a range of strain amplitudes due to comparable ferrite volume fractions and yielding characteristics. Both steels formed low-energy dislocation structures in the ferrite during cyclic straining.