Plasticity of high purity iron single crystals (I) 1. work hardening

Abstract

Work HardeningDedicated to Professor V. I. STARTSEV on the occasion of his 70th birthday High purity iron single crystals were deformed in tension in the temperature range 4.2 to 473 K. Work-hardening characteristics were determined and the plastic behaviour in dependence on temperature, strain rate and crystal orientation is discussed. The transition temperature between low-temperature and intermediate-temperature deformation regimes was found to be 250 K, the critical temperature estimated from the temperature dependence of the critical resolved shear stress is 380 K. A hump on the temperature dependence of the critical resolved shear stress was observed in the vicinity of 250 K. These observations are qualitatively explained by special mobilities of dislocations in b.c.c. lattice.Hochreine Eisen-Einkristalle wurden im Temperaturbereich 4,2 bis 473 K zugverformt. Die Verfestigungscharakteristika wurden bestimmt, und das plastische Verhalten in Abhangigkeit von Temperatur, Verformungsrate und Kristallorientierung wird diskutiert. Die obergangstemperatur zwischen Tieftemperatur-und Zwischentemperaturregime wurde zu etwa 250 K gefunden; die kritische Temperatur, abgeschatzt aus der Temperaturabhangigkeit der kritischen bezogenen Schubspannung, betragt ca. 380 K. Ein Ruckel in der Temperaturabhangigkeit der kritischen bezogenen Schubspannung wurde in der Umgebung von 250 K beobachtet. Dies ist durch spezielle Beweglichkeiten der Versetzungen im krz-Gitter erkliirbar.

Spatial strain correlations, machine learning, and deformation history in crystal plasticity

“…). It is common that a sample that had been processed in various ways, then polished, is further mechanically tested as a part of a component [1][2][3][4][5][6]. In such cases, characterizing the mechanical response of the sample requires either the precise history of the processing routes taken, or the precise knowledge of the particular state realized and its state variables.…”

“…Despite the multitude of origins, the success of strain gradients in capturing deformation history of plastically deformed materials, is based on the main spatial signatures of strain localization and shear banding [7,26]. Shear bands have been identified as possible indicators of prior deformation, given that the creation of slip bands during various smallload mechanical tests of polished samples, shows strong dependence on the prior deformation history [1,2,4]. However, the presence/absence of shear banding may not suffice for characterizing prior processing, and a more complete characterization of crystal plasticity history should require the classification of the full spatial correlations of stress and strain tensorial fields [21].…”

Deformation Correlations and Machine Learning: Microstructural inference and crystal plasticity predictions

“…Signatures of crystal plasticity, have been traditionally linked to strain localization, typically in the form of shear bands (Asaro and Lubarda, 2006;Bigoni and Hueckel, 1991). Shear bands have been identified as possible indicators of prior deformation: In particular, it has been shown that the creation of slip bands during various small-load mechanical tests strongly depend on the prior deformation history of a sample (Diehl and Hinzner, 1964;Novák et al, 1984aNovák et al, , 1984b. However, the presence or absence of shear bands may not suffice for characterizing prior processing.…”