Characterization of cyclic behavior, deformation mechanisms, and microstructural evolution of MarBN steels under high temperature conditions

Abstract

In this paper, the low cycle fatigue behaviour of MarBN steels at elevated temperatures is discussed. Four cyclic loading waveforms were applied to investigate both the mechanical and microstructural features. The mechanical results exhibit continuous cyclic softening and decelerated stress relaxation, recoverable viscoelasticity at both short and long time scales and irrecoverable viscoplastic mechanisms. Detailed microstructural characterisation was also conducted to investigate the rupture behaviour of the investigated steel. The microstructural findings indicate typical transgranular and ductile fracture behaviour, extensive sub-grain formation and structural refinement as well as significant decrease in hardness close to the fracture surface.

Hot dwell-fatigue behaviour of additively manufactured AlSi10Mg alloy: Relaxation, cyclic softening and fracture mechanisms

“…It is noteworthy that no conspicuous differences are detected between the fracture surfaces for fatigue and dwell-fatigue samples at the same temperatures. This suggests that the creep dwell does not significantly affect the fatigue fracture mode [38].…”

“…It can be seen that the frequency of local misorientation ranging between 0.5 • − 3 • is somewhat higher for the dwell-fatigued samples than in the LCF samples at the same temperatures, indicating that more subgrains are developed by introducing the dwells [10]. The extensive formation of subgrains arises from the greater rearrangement of dislocations at elevated temperatures [38] resulting in a decrease in dislocation density and contributing to the cyclic softening. Moreover, changes in the morphology of the Si from a dense population of micron sized intergranular Si and nanoscale intragranular Si particles to a much coarser distribution of intergranular Si particles leads to the significant decrease in the strength by Orowan strengthening and dislocation pileup [43].…”

Microstructure-Based Multiscale Modeling of Deformation in MarBN Steel under Uniaxial Tension: Experiments and Finite Element Simulations

“…Furthermore, they used EBSD to analyze the tensile failure mechanism of MarBN steel under various strain rates and temperatures [ 4 ]. Besides, Benaarbia et al [ 5 ] used EBSD technology to study the low cycle fatigue behavior of MarBN steel at high temperatures. Xu et al [ 6 ] used EBSD technology and hardness hardening diagram analysis method to study the microstructure evolution behavior of 9% Cr MarBN steel weld.…”