Non-destructive direct current potential drop assessment of forming-induced pre-damage in AISI 5115 steel

Lücker, Lukas; Lingnau, Lars; Walther, Frank

doi:10.1016/j.prostr.2022.12.046

Cited by 2 publications

(6 citation statements)

References 6 publications

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“…With regard to the axial stress states in the HCF regime, initial investigations were carried out by Luecker et al [ 29 ] in combination with the resistance-based methods to quantify the forming-induced ductile damage by full forward rod extrusion. Using the GOM Aramis SRX high-speed DIC system (Zeiss, Braunschweig, Germany), the changes in plastic strain amplitude could be analyzed and correlated with the electrical resistance measured using the Keithley 2182A nanovoltmeter measurement system (Keithley, Cleveland, OH, USA).…”

Section: Resultsmentioning

confidence: 99%

“…In addition to the current intensity, the duration of the delay (Figure 4b), which describes the delay of the voltage measurement after the polarity reversal, and the number of power line cycles (NPLC), which describes the sampling rate of the grid cycles of the general power grid, were considered (Table 2). An optimal current of I = 0.8 A, an NPLC of 1 and a delay of 0.02 s were determined, which represents a reliable compromise for the measurements [29]. In order to record damage development during fatigue testing, resistivity-based, structure-sensitive methods in the form of direct current potential drop (DCPD) measurements were used.…”

Section: Fatigue Testing Setup and Methodsmentioning

confidence: 99%

“…The influence of forming-induced ductile damage, which is dependent on the process parameter of the shoulder opening angle 2α, on the fatigue behavior in LCF has already been demonstrated for torsional and axial stresses [12,29,30]. The influence of forminginduced damage at superimposed axial-torsional stresses has not yet been determined.…”

Section: Axial-torsional and Uni-axial Fatigue Behaviormentioning

confidence: 99%

“…Resistometry-based methods will also be used to investigate fatigue damage assessments in terms of the change in electrical resistance due to pore formation or growth [ 29 ]. The long-term goal is to quantify the various influencing factors and to separate the damage mechanisms, especially with regard to forming-induced ductile and fatigue-induced damage.…”

Section: Introductionmentioning

confidence: 99%

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Separation of Damage Mechanisms in Full Forward Rod Extruded Case-Hardening Steel 16MnCrS5 Using 3D Image Segmentation

Lingnau,

Heermant,

Otto

et al. 2024

Materials

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In general, formed components are lightweight as well as highly economic and resource efficient. However, forming-induced ductile damage, which particularly affects the formation and growth of pores, has not been considered in the design of components so far. Therefore, an evaluation of forming-induced ductile damage would enable an improved design and take better advantage of the lightweight nature as it affects the static and dynamic mechanical material properties. To quantify the amount, morphology and distribution of the pores, advanced scanning electron microscopy (SEM) methods such as scanning transmission electron microscopy (STEM) and electron channeling contrast imaging (ECCI) were used. Image segmentation using a deep learning algorithm was applied to reproducibly separate the pores from inclusions such as manganese sulfide inclusions. This was achieved via layer-by-layer ablation of the case-hardened steel 16MnCrS5 (DIN 1.7139, AISI/SAE 5115) with a focused ion beam (FIB). The resulting images were reconstructed in a 3D model to gain a mechanism-based understanding beyond the previous 2D investigations.

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Section: Resultsmentioning

confidence: 99%

Section: Fatigue Testing Setup and Methodsmentioning

confidence: 99%

Section: Axial-torsional and Uni-axial Fatigue Behaviormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Separation of Damage Mechanisms in Full Forward Rod Extruded Case-Hardening Steel 16MnCrS5 Using 3D Image Segmentation

Lingnau,

Heermant,

Otto

et al. 2024

Materials

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“…The measurements in Figure 1 are obtained while the specimen is subjected to tensile loading. Voltage measurements are collected with constant current

I= 0.8\rm \,A

being applied between the contact points throughout the experiment [17, 18]. The material parameters that are identified for DP800 steel are given in Figure 2.…”

Section: Numerical Examplesmentioning

confidence: 99%

Characterisation of damage by means of electrical measurements: Numerical predictions

Güzel,

Kaiser,

Lücker

et al. 2023

Proc Appl Math and Mech

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Understanding damage mechanisms and quantifying damage is important in order to optimise structures and to increase their reliability. To achieve this goal, experimental‐ and simulation‐based techniques are to be combined. Different methods exist for the analysis of damage phenomena such as fracture mechanics, phase field models, cohesive zone formulations and continuum damage modelling. Assuming a typical ‐type damage formulation, the governing equations of continua that account for gradient‐enhanced ductile damage under mechanical and electrical loads are derived. The mechanical and electrical sub‐problems give rise to the local form of the balance equation of linear momentum, the micromorphic balance relation and the continuity equation for the electric charge, respectively. Experimental investigations indicate that changes in electrical conductivity arise due to the evolution of the underlying microstructure, for example, of cracks and dislocations. Therefore, motivated by deformation‐induced property changes, the effective electrical conductivity is assumed to be a function of the damage variable. This eventually allows the prediction of experimentally recorded changes in the electrical resistance due to mechanically‐induced damage processes. Interpreting the resistivity as a fingerprint of the material microstructure, the simulation approach proposed in the present work contributes to the development of non‐destructive electrical‐resistance‐based characterisation methods. To demonstrate the applicability of the proposed framework, different representative simulations are studied.

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Non-destructive direct current potential drop assessment of forming-induced pre-damage in AISI 5115 steel

Cited by 2 publications

References 6 publications

Separation of Damage Mechanisms in Full Forward Rod Extruded Case-Hardening Steel 16MnCrS5 Using 3D Image Segmentation

Separation of Damage Mechanisms in Full Forward Rod Extruded Case-Hardening Steel 16MnCrS5 Using 3D Image Segmentation

Characterisation of damage by means of electrical measurements: Numerical predictions

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