Estimation of Local Plastic Deformation of Polycrystalline Materials

Final properties of formed steel or another alloy pieces are affected even by plastic deformation of material. Therefore it is needful to know detail structure changes of material under conditions of plastic deformation caused by forming, grinding, drilling etc. Estimation of the deformation based on its observable macroscopic effects doesn’t correspond fully with microscopic structural changes in whole volume of deformed parts and such estimation is quite impossible in case if only surface layers are deformed. It is possible to obtain value of strain by measurement of grain boundary deformation. Effect of grains boundaries self-orientation caused by grains deformation can be identified on metallographic cut. Stereological measurement of degree of grain boundary orientation is relatively simple if axes of orientation are known (as it is in most of deformation processes). Preferred direction of grains boundaries orientation is the same as direction of deformation; however orientation is not the same thing as deformation. Therefore model of conversion of degree of grain boundary orientation to deformation based on an idealized shape of grains has been proposed. This conversion model is independent on an initial grain size – strain depends only on the shape of the grain and does not depend on its dimension. It allows experimental estimation of local plastic deformation by means of measurement of grain boundary orientation in various areas of plastically deformed parts.

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Influence of Drill Wear to Local Plastic Deformation in the Wall of Drilling Hole

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.606.77 ◽

2014 ◽

Vol 606 ◽

pp. 77-80 ◽

Cited By ~ 1

Author(s):

Maroš Martinkovič ◽

Peter Pokorný ◽

Petra Bodišová

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

Grain Boundaries ◽

Great Influence ◽

Machining Process ◽

Axial Component ◽

Local Plastic ◽

Work Surface ◽

Structure Changes ◽

Local Plastic Deformation

Final properties of plastic deformed parts of workpieces are affected by production technological processes. Therefore it is needful to know detailed structure changes of plastic deformed material caused by machining - grinding, drilling etc. Friction of tool to work surface caused one of three areas of plastic deformation in cutting zone. It has great influence to quality of work surface and local mechanical properties of surface layer of workpiece. Influence of drill wear to local plastic deformation in deformation zone around the surface of drilled holes was investigated. Two types of cutting tools were used: high speed steel drill IZAR HSSCO with diameter 6,0 mm surface hardened by boriding and the same one without boride layer. Standard cutting parameters were used. During the machining process, axial component of cutting force and torque were observed. The work piece was bulk from carbon steel Ck45 (1.0503). Wear of the tool was estimated as a wide of wear on tool flank. The local strain in analysed place of probes on their sections was obtained by stereological measurement of degree of grain boundaries orientation, which is proportional to grain boundaries deformation degree. Estimation of grain boundary orientation degree leads to determination of local plastic deformation in arbitrary place of workpiece. These results lead to detailed analysis of material structure changes caused by drilling from which local mechanical properties result.

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Estimation of Local Plastic Deformation in a Bulk of Polycrystalline Materials

Journal of Engineering Research ◽

10.36909/jer.11229 ◽

2021 ◽

Vol 9 ◽

Author(s):

Monika Vyskočová ◽

◽

Maroš Martinkovič ◽

Martin Necpál ◽

Maroš Vyskoč ◽

...

Keyword(s):

Plastic Deformation ◽

Model Simulation ◽

Deformation Analysis ◽

Polycrystalline Materials ◽

Cold Forming ◽

Local Plastic ◽

Tensile Tester ◽

The Difference ◽

Deform Program ◽

Local Plastic Deformation

The article deals with the local plastic deformation analysis after cold forming. The technology of drawing seamless steel tubes was used to obtain cold-formed samples. The tubes were manufactured by a Tinius Olsen 300ST tensile tester with a 6 ° and 12 ° die drawn without and with an inner mandrel. Based on orientation size recalculated by stereology and applying Monte Carlo method a mathematical conversion model was developed. Implemented model together with surface measurements and structure characteristics were used to get the orientation to the size of the deformation. Thus, the actual (logarithmic) deformations and local stresses were determined. Comparison of experimentally measured values of the actual local plastic deformation with the deformation calculated found on the model simulation in the Deform program defined the significance of the differences assessed by means of a statistical T-test. All differences in the values of the local plastic deformation with respect to the position were evaluated as statistically insignificant and therefore the difference between the experimental calculation and the simulation is random.

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Estimation of Local Plastic Deformation in Cutting Zone during Turning

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.662.173 ◽

2015 ◽

Vol 662 ◽

pp. 173-176 ◽

Cited By ~ 2

Author(s):

Maroš Martinkovič ◽

Peter Pokorný

Keyword(s):

Plastic Deformation ◽

Local Strain ◽

Shear Plane ◽

Large Strains ◽

Strain Rates ◽

Machined Surface ◽

Local Plastic ◽

Structure Changes ◽

Cutting Zone ◽

Local Plastic Deformation

Local plastic deformation in cutting zone during turning is affected by technological conditions of the processes. Therefore it is needful to know detail structure changes of plastic deformed material during machining. It is localised, asymmetric deformation which operates at very large strains and exceptionally high strain rates. Three areas of intensive local plastic deformation in cutting zone were observed: the primary area of plastic deformation in shear plane, the secondary area of plastic deformation caused by friction of chip to tool face and the tertiary area of plastic deformation caused by friction of tool to machined surface. Local strain in these three areas was estimated by measurement of deformation of grains on metallographic cut. The effect of grains boundaries self-orientation caused by grains deformation was evaluated using stereology. But the orientation is not the same as deformation and so a correlation between the grain deformation and grain orientation was used. The turning piece was made of CK45 (1.0503) carbon steel. The specimen of cutting zone was obtained by using internal stress method.

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Local plastic deformation in the vicinity of grain boundaries in Fe–3 mass% Si alloy bicrystals and tricrystal

Journal of Materials Science ◽

10.1007/s10853-014-8150-2 ◽

2014 ◽

Vol 49 (14) ◽

pp. 4698-4704 ◽

Cited By ~ 10

Author(s):

Sadahiro Tsurekawa ◽

Yuta Chihara ◽

Kyohei Tashima ◽

Seiichiro Ii ◽

Pavel Lejček

Keyword(s):

Plastic Deformation ◽

Grain Boundaries ◽

Local Plastic ◽

Local Plastic Deformation

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A Cathodoluminescence Study of the Defects Created by the Degradation of High Power AlGaAs/GaAs Multiemitter Laser Bars

MRS Proceedings ◽

10.1557/proc-1108-a06-04 ◽

2008 ◽

Vol 1108 ◽

Author(s):

Alonso Martín-Martín ◽

Manuel Avella ◽

M. Pilar Iñiguez ◽

Juan Jiménez ◽

Myriam Oudart ◽

...

Keyword(s):

Plastic Deformation ◽

High Power ◽

Defect Formation ◽

Local Heating ◽

Laser Operation ◽

Thermomechanical Model ◽

Local Plastic ◽

Local Plastic Deformation ◽

Cathodoluminescence Study

AbstractIn this work we study the defects responsible for the degradation of high power AlGaAs based laser bars. The mirror and cavity degradations are studied by spectral cathodoluminescence (CL) imaging. Following the analysis of the CL images the main defects generated during the laser operation are revealed, both facet and intracavity defects are observed. A thermomechanical model is used to describe the very beginning of the defect formation. The defects are formed by a local plastic deformation induced by local heating at defects.

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