Enhancing grain refinement in polycrystalline materials using surface mechanical attrition treatment at cryogenic temperatures

2013 ◽  
Vol 69 (6) ◽  
pp. 461-464 ◽  
Author(s):  
K.A. Darling ◽  
M.A. Tschopp ◽  
A.J. Roberts ◽  
J.P. Ligda ◽  
L.J. Kecskes
Keyword(s):  
Grain Refinement ◽  
Surface Mechanical Attrition Treatment ◽  
Polycrystalline Materials ◽  
Cryogenic Temperatures ◽  
Mechanical Attrition

Surface Nanocrystallization by Surface Mechanical Attrition Treatment

2008 ◽  
Vol 579 ◽  
pp. 91-108 ◽  
Author(s):  
N.R. Tao ◽  
Jian Lu ◽  
K. Lu
Keyword(s):  
Surface Layer ◽  
Grain Refinement ◽  
Mechanical Twinning ◽  
Surface Mechanical Attrition Treatment ◽  
Formation Mechanisms ◽  
Chemical Compositions ◽  
Tensile Fatigue ◽  
Mechanical Attrition ◽  
And Performance ◽  
Mechanical Twins

Based on strain-induced grain refinement, a novel surface mechanical attrition treatment (SMAT) technique has been developed to synthesize a nanostructured surface layer on metallic materials in order to upgrade their overall properties and performance without changing their chemical compositions. In recent several years, the microstructures and properties of surface layer were systematically investigated in various SMAT metals and alloys, including b.c.c., f.c.c. and h.c.p. crystal structures. Different grain refinement approaches and nanocrystalline formation mechanisms were identified in these deformed materials, involving dislocation activities, mechanical twinning and interaction of dislocations with mechanical twins. The properties of the surface layer were measured by means of hardness, tensile, fatigue and wear tests. The enhanced properties of the surface layer are mainly attributed to the strain-induced grain refinement. In this work, we reviewed the microstructures and properties of surface layer in the SMAT materials.

Influence of Surface Mechanical Attrition Treatment Attrition Media on the Surface Contamination and Corrosion of Magnesium

CORROSION ◽  
10.5006/0763 ◽  
2012 ◽  
Vol 69 (6) ◽  
pp. 527-535 ◽  
Author(s):  
D. Fabijanic ◽  
A. Taylor ◽  
K.D. Ralston ◽  
M.-X. Zhang ◽  
N. Birbilis
Keyword(s):  
Grain Refinement ◽  
Surface Composition ◽  
Optical Emission ◽  
Surface Contamination ◽  
Grain Structure ◽  
Surface Mechanical Attrition Treatment ◽  
Ultrafine Grain ◽  
Surface Residual Stress ◽  
Mechanical Attrition ◽  
Steel Balls

Surface mechanical attrition treatment (SMAT) is a mechanical peening process used to generate ultrafine grain surfaces on a metal. SMAT was carried out on pure magnesium using different attrition media (zirconia [ZiO2], alumina [Al2O3], and steel balls) to observe the effect on microstructure, surface residual stress, surface composition, and corrosion. Surface contamination from SMAT was characterized using glow discharge optical emission spectroscopy (GDOES). The SMAT process produced a refined grain structure on the surface of Mg but resulted in a region of elemental contamination extending ~10 μm into the substrate, regardless of the media used. Consequently, SMAT-treated surfaces showed an increased corrosion rate compared to untreated Mg, primarily through increased cathodic kinetics. This study highlights the issue of contamination resulting from the SMAT process, which is a penalty that accompanies the significant grain refinement of the surface produced by SMAT. This must be considered if attempting to exploit grain refinement for improving corrosion resistance.

Modelling of Grain Refinement Induced by SMAT Process, Using a Complete Numerical Chaining Methodology

2013 ◽  
Vol 762 ◽  
pp. 295-300
Author(s):  
Souhail Benafia ◽  
Delphine Retraint ◽  
Benoit Panicaud ◽  
Lea le Joncour ◽  
Emmanuelle Rouhaud ◽  
...  
Keyword(s):  
Finite Element ◽  
Grain Refinement ◽  
Material Properties ◽  
Element Model ◽  
Surface Mechanical Attrition Treatment ◽  
Metallic Materials ◽  
Element Analysis ◽  
Mechanical Attrition ◽  
Micromechanical Approach ◽  
The Impact

Surface Mechanical Attrition Treatment (SMAT) is a recent process that enables to nanocrystallise the surface of metallic alloys. It can thus enhance mechanical properties of the treated material by inducing a grain refinement down to the nanometre scale, in the top surface layer. This nanocrystallisation process leads to different effects that were successively studied on several metallic materials. In the present work, investigations are carried out on the modelling of SMAT. A simulation of the shot dynamics is performed using different process parameters, with the aim to obtain the impact velocity field on the treated surface. This field is then used as an input for a finite element model to predict the induced grain refinement. The evolution of the micro and nanostructures are then calculated using a micromechanical approach, which takes into account the dislocations and their interactions. Coupled with a finite element analysis, this approach enables to deduce the influence of the process on the macroscopic material properties, whatever the geometry of the sample.

scholarly journals Strain-induced grain refinement of cobalt during surface mechanical attrition treatment

2005 ◽  
Vol 53 (3) ◽  
pp. 681-691 ◽  
Author(s):  
X. Wu ◽  
N. Tao ◽  
Y. Hong ◽  
G. Liu ◽  
B. Xu ◽  
...  
Keyword(s):  
Grain Refinement ◽  
Surface Mechanical Attrition Treatment ◽  
Mechanical Attrition

Ultrasonic Evaluation of Compressive Residual Stress of Surface Treated Metals

2005 ◽  
Vol 490-491 ◽  
pp. 184-189 ◽  
Author(s):  
Farid Belahcene ◽  
Xiaolai Zhou ◽  
Jian Lu
Keyword(s):  
Experimental Data ◽  
Residual Stresses ◽  
Nondestructive Evaluation ◽  
Subsurface Layer ◽  
Surface Mechanical Attrition Treatment ◽  
Shallow Subsurface ◽  
Ultrasonic Evaluation ◽  
Mechanical Attrition ◽  
Machine Parts ◽  
Compressive Residual Stresses

Shot peening is an effective method of improving fatigue performance of machine parts in the industry by producing a thin surface layer of compressive residual stresses that prevents crack initiation and retards crack growth during service. Nondestructive evaluation of the prevailing compressive residual stresses in the shallow subsurface layer is realized by the critically refracted longitudinal (Lcr) waves. This paper presents experimental data obtained on SMAT (surface mechanical attrition treatment) steel alloy S355 sample. Comparative travel-time shows that there are statistically significant differences in treated and untreated specimen. With knowledge of the acoustoelastic constants which are obtained by a test calibration, the experimental data indicates that compressive residual stresses are distributed near subsurface (hundreds of micron). These stress results show that the Lcr technique is efficient for evaluation of residual stresses after the surface treatment.

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