Effect of Crystallographic Orientation on Mechanical Properties of Steel Sheets by Depth Sensing Indentation (original) (raw)
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Journal of Constructional Steel Research, 2014
Microstructural compositions present in the weld zone of a structural steel were analyzed using nanoindentation and optical microscopy. Nanoindentation was performed on three different locations of the weld zone, including base metal (BM), heat-affected zone (HAZ) and weld metal (WM). Hundred points were indented on each location. The elastic modulus and hardness for each indenting point were then extracted from the nanoindentation results. Considering the mechanical properties as the characteristics of microstructures, statistical analysis with the deconvolution technique was applied to identify the microstructures and the corresponding volume fractions in BM, HAZ and WM. From the observations of optical microscopy and nanoindentation, it was shown that nanoindentation is acceptable in the verification of microstructural compositions and corresponding volume fractions in steel at three different locations of the weld zone. Moreover, the results showed that a microstructure of steel, ferrite, could be mechanically characterized in two types, low and high stiffness ferrite.
Scientific Reports, 2015
The full understanding of the deformation mechanisms in nanostructured bainite requires the local characterization of its mechanical properties, which are expected to change from one phase, bainitic ferrite, to another, austenite. This study becomes a challenging process due to the bainitic nanostructured nature and high Young’s modulus. In this work, we have carried out such study by means of the combination of AFM-based techniques, such as nanoindentation and Peak Force Quantitative Nanomechanical Mapping (PF-QNM) measurements. We have addressed critically the limits and advantages of these techniques and been able to measure some elastoplastic parameters of both phases. Specifically, we have analyzed by PF-QNM two nanostructured bainitic steels, with a finer and a coarser structure and found that both phases have a similar Young’s modulus.
Characterization Of Thermally Affected Steels By Nanoindentation
2018
The thermal affectation is the basis of metallurgical modifications of the base metal which can induce fragilities, decreases in mechanical strength, lack of ductility ... These modifications depend on the material examined, the process used, the mode of operation followed ... This research is devoted to the experimental study, whose objective is the study of low-carbon steels who sustained of the various heat treatments. Then, the instrumented nanoindentation test is developed to analyze the characteristic loading and unloading curves of the examined specimens. In this case, we focus on the effect of heat treatments on the metallographic examination and the mechanical properties of the studied steels. At the same time, we study the coherence of the results obtained between the heat treatment and the nanoindentation process in the determination of elasticity modulus and hardness. Résumé L'affectation thermique est à la base des modifications métallurgiques du métal de base qui p...
Journal of Materials Research, 2012
ABSTRACT A new technique based on the detection of the amplitude of the second harmonic was described in a previous paper. To compute the elastic modulus and the hardness of materials, the technique uses only the derivative of the contact radius with respect to the indentation depth. For this reason, this method is applicable only to homogeneous materials. In this paper, the method is extended to any materials with constant Young modulus. The indentation depth value is not needed at all, thus eliminating uncertainties related to the displacement measurement, which are very influent at small penetration depths. Furthermore, we also explain how to compute the indentation depth from the detection of the amplitude of the second harmonic. This new measurement technique was tested on three samples: fused silica, Poly(methyl methacrylate) (PMMA), and calcite, which is expected to exhibit indentation size effect. The obtained results show that mechanical properties and the indentation depth can be determined with good accuracy for penetration depths between 25 and 100 nm using this method.
2015
High strength rail steels are used in heavy haul railway in Australia. However, there is still lack of understanding on the microstructures of these rail steels. Three high strength rail steels were investigated in this research. This study has three major purposes: (1) to determine microstructure quantitatively and qualitatively using SEM; (2) to investigate mechanical properties such as Young’s modulus and hardness using nanoindentation and microhardness test; (3) to correlate microstructure with mechanical properties for the high strength rail steels. In the first part, microstructure characterized by interlamellar spacing was determined quantitatively along the depth from gauge corner (GC) surface of a rail head. The results show that the interlamellar spacing increases with the depth from GC surface. This study then investigated the mechanical properties of these rail steels using nanoindentation. The Young’s modulus obtained from nanoindentation is in good agreement with monot...
Nanoindentation behaviour and microstructure of several wootz- type steels
The nano-mechanical properties of an as-deposited composite Au/Cr/Si film comprising a Au layer with a thickness of 800 nm and a Cr adhesive layer with a thickness of 10 nm deposited on a Si (100) substrate are investigated by performing nanoindentation tests to a maximum depth of 1500 nm. The microstructural evolutions of as-deposited indented specimens and specimens annealed at temperatures of 523 K, 623 K or 723 K for 2 min are then examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The loading curve for the as-deposited Au/Cr/Si thin film is found to be continuous and smooth. However, the unloading curve has a prominent popout feature. The hardness and Young's modulus of the Au/Cr/Si thin film indented to a maximum depth of 1500 nm are determined to be 2.7 GPa and 110 GPa, respectively. In the as-deposited sample, the microstructure of the indentation zone is characterised by a mixed structure comprising amorphous phase and nanocrystalline phase. Furthermore, well-defined Au, Cr and Si layers are observed in the interfacial region of the thin film. However, at the highest annealing temperature of 723 K, the microstructure of the indentation zone is recovered to a perfect diamond cubic single crystalline state. Finally, silicidation of the Cr layer takes place in all the annealed samples, resulting in the formation of isolated nano-islands of Cr.
Novel nanoindentation method for characterising multiphase materials
Thin solid films, 1997
We present the nano-hardness tester (NHT), a new depth-sensing instrument with a differential capacitive sensor providing nanometer depth resolution and allowing partial elimination of the frame compliance. With micron lateral positioning of the sample and ...
Material Design & Processing Communications, 2020
The aim of this investigation is to characterize the mechanical properties at the microstructural level in ferritic ductile iron. The analysis involves microstructural characterization, nanoindentation testing, atomic force microscopy analysis, and the application of an inverse algorithms proposed in the literature. The results show that, because of microsegregation, different regions of a single-phase ferritic matrix have different elastic-plastic behavior. The methodology developed in this work becomes useful to evaluate the mechanical properties along the metallic matrix of other ductile iron microstructures.