Plastic Flow and Shear Banding in Refractory Metals and Martensitic Steels at Very High Shearing Rates

2001 ◽  
Author(s):  
Rodney J. Clifton
Keyword(s):  
Plastic Flow ◽  
Shear Banding ◽  
Refractory Metals ◽  
Martensitic Steels ◽  
High Shearing ◽  
Very High

Strain-rate dependence of hardening and softening in compression of a bulk-metallic glass

2007 ◽  
Vol 22 (10) ◽  
pp. 2655-2658 ◽  
Author(s):  
W.H. Jiang ◽  
F.X. Liu ◽  
F. Jiang ◽  
K.Q. Qiu ◽  
H. Choo ◽  
...  
Keyword(s):  
Flow Stress ◽  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Plastic Flow ◽  
Shear Banding ◽  
Constant Strain Rate ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Plastic Flow Stress

We investigated the effect of strain rate on the plastic-flow stress of a Zr-based bulk-metallic glass in quasistatic compression. The results indicate that the plastic-flow stress is dependent on the strain rate: an increase in the strain rate leads to a decrease in the plastic-flow stress, and vice versa. However, simply loading, unloading, and reloading at a constant strain rate do not change the plastic-flow stress. This strain-rate dependence of the plastic-flow stress may be related to shear-banding operations.

Quasi-static rheology of foams. Part 2. Continuous shear flow

2007 ◽  
Vol 587 ◽  
pp. 45-72 ◽  
Author(s):  
ALEXANDRE KABLA ◽  
JULIEN SCHEIBERT ◽  
GEORGES DEBREGEAS
Keyword(s):  
Steady State ◽  
Stress Field ◽  
Plastic Flow ◽  
Shear Banding ◽  
Steady State Regime ◽  
Yield Strain ◽  
Temporal Correlations ◽  
Continuous Shear ◽  
Plastic Event ◽  
State Regime

The evolution of a bidimensional foam submitted to continuous quasi-static shearing isinvestigated both experimentally and numerically. We extract, from the images of the sheared foam, the plastic flow profiles as well as the local statistical properties of the stress field. When the imposed strain becomes larger than the yield strain, the plastic events develop large spatial and temporal correlations, and the plastic flow becomes confined to a narrow shear band. This transition and the steady-state regime of flow are investigated by first focusing on the elastic deformation produced by an elementary plastic event. This allows us to understand (i) the appearance of long-lived spatial heterogeneities of the stress field, which we believe are at the origin of the shear-banding transition, and (ii) the statistics of the dynamic fluctuations of the stress field induced by plastic rearrangements in the steady-state regime. Movies are available with the online versionof the paper.

Plastic flow in dynamic compression of a Zr-based bulk metallic glass

2006 ◽  
Vol 21 (6) ◽  
pp. 1570-1575 ◽  
Author(s):  
W.H. Jiang ◽  
F.X. Liu ◽  
D.C. Qiao ◽  
H. Choo ◽  
P.K. Liaw
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Plastic Flow ◽  
Dynamic Compression ◽  
Maximum Shear Stress ◽  
Shear Banding ◽  
Shear Bands ◽  
Free Volume Model ◽  
Geometrically Constrained

Using geometrically constrained specimens, the plastic flow behaviors of the as-cast and the relaxed Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 bulk metallic glass in the dynamic compression were investigated. Both alloys exhibit a significant plasticity in the dynamic compression. The plastic deformation in both alloys is still inhomogeneous, which is characterized by the serrated plastic flow and the formation of shear bands. Free volumes affect the shear banding and the plastic flow. The reduced free volume results in the deviation of the shear banding direction from the maximum shear stress. The relaxed alloy exhibits the obvious stress overshoot, which is consistent with the theoretical prediction using a free volume model.

On the Cutting of Metals: A Mechanics Viewpoint

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Dinakar Sagapuram ◽  
Anirudh Udupa ◽  
Koushik Viswanathan ◽  
James B. Mann ◽  
Rachid M’Saoubi ◽  
...  
Keyword(s):  
Plastic Flow ◽  
Chip Formation ◽  
Metal Cutting ◽  
Large Strain ◽  
Shear Banding ◽  
Continuous Shear ◽  
Recent Developments ◽  
Flow Phenomena ◽  
The Stability

Abstract The mechanics of large-strain deformation in cutting of metals is discussed, primarily from viewpoint of recent developments in in situ analysis of plastic flow and microstructure characterization. It is shown that a broad range of deformation parameters can be accessed in chip formation—strains of 1–10, strain rates of 10–105/s, and temperatures up to 0.7Tm—and controlled. This range is far wider than achievable by any other single-stage, severe plastic deformation (SPD) process. The resulting extreme deformation conditions produce a rich variety of microstructures in the chip. Four principal types of chip formation—continuous, shear-localized, segmented, and mushroom-type—as elucidated first by Nakayama (1974, “The Formation of ‘Saw-Toothed Chip’ in Metal Cutting,” Proceedings of International Conference on Production Engineering, Tokyo, pp. 572–577) are utilized to emphasize the diverse plastic flow phenomena, especially unsteady deformation modes that prevail in cutting. These chip types are intimately connected with the underlying flow, each arising from a distinct mode and triggered by an instability phenomenon. The role of plastic flow instabilities such as shear banding, buckling, and fracture in mediating unsteady flow modes is expounded, along with consequences of the flow modes and chip types for the cutting. Sinuous flow is shown to be the reason why gummy (highly strain-hardening) metals, although relatively soft, are so difficult to cut. Synthesizing the various observations, a hypothesis is put forth that it is the stability of flow modes that determines the mechanics of cutting. This leads to a flow-stability phase diagram that could provide a framework for predicting chip types and process attributes.

Irradiation Creep and Swelling of Russian Ferritic-Martensitic Steels Irradiated to Very High Exposures in the BN-350 Fast Reactor at 305–335°C

2004 ◽  
Vol 1 (9) ◽  
pp. 11342 ◽  
Author(s):  
YV Konobeev ◽  
AM Dvoriashin ◽  
SI Porollo ◽  
SV Shulepin ◽  
NI Budylkin ◽  
...  
Keyword(s):  
Fast Reactor ◽  
Martensitic Steels ◽  
Irradiation Creep ◽  
Very High

scholarly journals Viscous Shear Banding in Cutting of Metals

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Dinakar Sagapuram ◽  
Koushik Viswanathan
Keyword(s):  
Plastic Flow ◽  
Flow Instability ◽  
Liquid Metals ◽  
Shear Banding ◽  
Shear Bands ◽  
Local Deformation ◽  
Flow Rule ◽  
Sliding Mechanism ◽  
Viscous Shear ◽  
Local Shear

Shear banding is a type of plastic flow instability with often adverse implications for cutting and deformation processing of metals. Here, we study the mechanics of plastic flow evolution within single shear bands in Ti- and Ni-based alloy systems. The local shear band displacement profiles are quantitatively mapped at high resolution using a special micromarker technique. The results show that shear bands, once nucleated, evolve by a universal viscous sliding mechanism that is independent of microstructural details. The evolution of local deformation around the band is accurately captured by a momentum diffusion equation based on a Bingham-type flow rule. The predicted band viscosity is very small, compared to those of liquid metals. A plausible explanation for this small viscosity and fluid-like behavior at the band, based on phonon drag, is presented.

Plastic flow properties and fracture toughness characterization of unirradiated and irradiated tempered martensitic steels

2007 ◽  
Vol 367-370 ◽  
pp. 527-538 ◽  
Author(s):  
P. Spätig ◽  
R. Bonadé ◽  
G.R. Odette ◽  
J.W. Rensman ◽  
E.N. Campitelli ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Plastic Flow ◽  
Martensitic Steels ◽  
Flow Properties
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