Deformation (engineering)

About: Deformation (engineering) is a research topic. Over the lifetime, 41560 publications have been published within this topic receiving 899757 citations. The topic is also known as: deformation.

Critical review of elastic and plastic thermal contact conductance models and comparison with experiment

Abstract: More than 450 thermal contact resistance data points obtained from isotropic conforming rough surfaces for five different materials; Ni200, SS304, two Zirconium alloys and Al6061 have been compared with the existing elastic and plastic models. For the first time data have been reduced to a dimensionless form assuming both elastic as well as plastic deformation. Normally data were compared with either the elastic model or the plastic model assuming a type of deformation a priori. The relative merits of different models and the surface factors influencing the mode of deformation are still not clear. Hence the aim of the present work was to compare most of the models available in the literature with themselves as well as with isotropic data. Comparison showed that generally smoother surfaces deform elastically and rougher ones plastically. However there are some data sets which compare well with both the elastic as well as the plastic models. 20 refs.

Micromechanisms of dynamic fracture of ductile high-strength steel

Abstract: Multiscale micromechanisms of dynamic fracture of ductile high-strength Cr-Ni-Mo-V steel are studied by combining a laser interference technique and conventional techniques of optical and electron microscopy. Two scale levels of high-rate strain and fracture were found to form the translational and rotational modes of material motion during shock wave propagation—mesoscopical (0.1–10 μm) and superstructural (50–500 μm). The kinetic and mechanical characteristics of materials at the adjacent scale levels turn out to be in opposite phases relative to each other, strength-characteristics closely connecting with the particle velocity dispersion. Heterogeneous dynamic deformation appears to be realized either in the form of shear bands or in the form of rotational vortices depending on the ratio of particle velocity dispersion and average particle velocity. During dynamic deformation the changing of carbide sizes and lattice parameter occurs, the intensity of these processes being dependent on the mesovolume velocity dispersion as well.

Effect of initial textures on deformation mechanisms and texture evolutions of Zrα polycrystals deformed by channel-die compression tests

Abstract: Channel die compression tests were performed at room temperature on zirconium polycrystalline samples (Zr 702) up to 40% plastic strain. Three initial textures ( T3, T4 and T5 ) with 〈c〉 axes concentrations along the die axes (ND, TD and LD) are considered. The macroscopic stress-strain curves, the active mechanisms (slip and twinning systems) and the texture evolutions obtained for T3, T4 and T5 show an anisotropic behaviour of the material. Identification of the deformation modes by EBSD (Electron Back Scattering Diffraction) indicates an important contribution of 100 prismatic glide in the different samples. Estimates of twinned volume fractions show an important activation of 102 twinning in the T5 samples. The correlation between the active mechanisms and the texture evolutions is partly explained by geometrical considerations.

Effects of Ga Content on Dynamic Recrystallization and Mechanical Properties of High Strain Rate Rolled Mg–Ga Alloys

Abstract: The Mg–xGa (x = 1, 2, 3 and 5 in mass%) alloys are subjected to high strain rate rolling (HSRR) at 275 °C with the rolling strain rate of 9.1 s−1 to develop high performance Mg alloy sheets with high plasticity. Effects of Ga content on microstructure and mechanical properties of the Mg–Ga alloys are investigated by SEM, XRD, tensile testing and etc. The Ga addition can reduce the critical strain of DRX in Mg alloys, which is associated with the reduced stacking fault energy, the increased twinning density during deformation and the more DRX nucleation sites during HSRR. With the Ga content increasing from 2 to 3%, the reduced DRX degree is attributable to the hindrance of dynamic precipitates. With the Ga content increasing from 3 to 5%, the slightly increased DRX degree can be ascribed to the relatively coarse precipitates. The Mg–2 Ga alloy sheet, featured with complete DRX, exhibits an ultra-high plasticity (with the elongation to rupture of 36.6%) and a relatively low anisotropy of yield strength and plasticity. The Mg–5 Ga alloy sheet has the best comprehensive mechanical properties, with the ultimate tensile strength of 292 MPa, yield strength of 230 MPa and elongation to rupture of 30.3%, which can be ascribed to the combination of grain refinement strengthening and precipitation strengthening. Effects of Ga content on microstructure, dynamic recrystallization (DRX) and mechanical properties of the Mg-Ga alloys prepared by high strain rate rolling (HSRR) are systematically studied. Among all the alloys, the HSRRed Mg-2Ga alloy exhibits the smallest DRX critical strain, an ultrahigh plasticity (δ up to 36.6%) and a low anisotropy of yield strength and plasticity, due to the complete DRX. The HSRRed Mg-5Ga alloy shows the optimal mechanical properties, with σb of 292 MPa, σ0.2 of 230 MPa and δ of 30.3%. The high strength is mainly attributed to precipitation strengthening and grain refinement strengthening.