Microstructural response and grain refinement mechanism of commercially pure titanium subjected to multiple laser shock peening impacts

Laser shock peening (LSP) is one of the innovative technique that produces a compressive residual stress on the surface of metallic materials, thereby significantly increasing its fatigue life in applications where failure is caused by surface-initiated cracks. The specimens were treated with laser shock waves with different processing parameters, and characterization studies were made on treated specimens. The purpose of the present study was to investigate the influence of Nd:YAG laser on commercially pure titanium (CP-Ti) used in prosthetic dental restorations. The treatment influenced change in microstructure, micro hardness, surface roughness, and wear resistance characteristics. Though CP-Ti is considered as an excellent material for dental applications due to its outstanding biocompatibility, it is not suitable when high mastication forces are applied. In the present study, pulsed Nd:YAG laser surface treatment technique was adopted to improve the wear resistance of CP-Ti. The wear test pin specimens of CP-Ti were investment cast with centrifugal titanium casting machine. The wear properties of specimens were evaluated after LSP on a “pin-on-disc” wear testing tribometer, as per ASTM G99-05 standards. The results of the wear experiment showed that the treated laser surface has higher wear resistance, micro hardness, and surface roughness compared to as-cast samples. The improvement of wear resistance may be attributed due to grain refinement imparted by LSP processes. The microstructure, wear surfaces, wear debris, and morphology of the specimen were analyzed by using optical electron microscope, scanning electron microscope, and X-ray diffraction (XRD). The data were compared using ANOVA and post-hoc Tukey tests. The characteristic change resulted in increase in wear resistance and decrease in wear rate. Hence, it is evident that the more reliable and removable partial denture metal frameworks for dental prostheses may find its applications.

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Dislocation density-based study of grain refinement induced by laser shock peening

Optics & Laser Technology ◽

10.1016/j.optlastec.2019.105827 ◽

2020 ◽

Vol 121 ◽

pp. 105827 ◽

Cited By ~ 6

Author(s):

Cheng Wang ◽

Long Wang ◽

Chuan-Li Wang ◽

Kun Li ◽

Xiao-Gui Wang

Keyword(s):

Dislocation Density ◽

Grain Refinement ◽

Laser Shock Peening ◽

Laser Shock ◽

Shock Peening

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Tailoring the bioactivity of commercially pure titanium by grain refinement using groove pressing

Materials Science and Engineering C ◽

10.1016/j.msec.2009.10.002 ◽

2010 ◽

Vol 30 (1) ◽

pp. 203-208 ◽

Cited By ~ 30

Author(s):

A. Thirugnanam ◽

T.S. Sampath Kumar ◽

Uday Chakkingal

Keyword(s):

Grain Refinement ◽

Pure Titanium ◽

Commercially Pure Titanium ◽

Commercially Pure

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Characterization of the Microstructure, Local Macro-Texture and Residual Stress Field of Commercially Pure Titanium Grade 2 Prepared by CONFORM ECAP

Metals ◽

10.3390/met8121000 ◽

2018 ◽

Vol 8 (12) ◽

pp. 1000 ◽

Cited By ~ 1

Author(s):

Gergely Németh ◽

Klaudia Horváth ◽

Charles Hervoches ◽

Petr Cejpek ◽

Jan Palán ◽

...

Keyword(s):

Residual Stress ◽

Neutron Diffraction ◽

Grain Refinement ◽

Residual Strain ◽

Pure Titanium ◽

Asymmetric Distribution ◽

Commercially Pure Titanium ◽

X Ray ◽

Commercially Pure ◽

Titanium Grade

The paper investigated the residual strain and stress distribution, microstructure, and macro-texture along the transverse direction of commercially pure titanium grade 2 samples prepared by the CONFORM ECAP technique. This method belongs to the severe plastic deformation methods; hence, it could be assumed that residual stress fields would be present in the work-pieces. Residual stresses cannot be directly measured; thus, neutron diffraction measurements, Electron back-scatter diffraction (EBSD) investigations, and local X-ray macro-texture measurements were performed in different regions of the sample to determine the data for the residual stress calculation. The calculation was based on the modified Kröner model. Neutron diffraction strain scans and residual stress calculations revealed that symmetrical residual strain and stress gradients with compression character were present in the axial and hoop direction after one and two passes. Asymmetric distribution of the residual strains and stresses remained after the third pass of the CONFORM ECAP. EBSD investigations showed that after the first pass, significant grain refinement occurred; however, further passes did not cause any dramatic grain refinement. X-ray texture measurements revealed that local macro-texture was dependent on the number of passes of the CONFORM ECAP and on the investigated area in the samples.

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Dislocation Density-Based Grain Refinement Modeling of Orthogonal Cutting of Commercially Pure Titanium

ASME 2011 International Manufacturing Science and Engineering Conference, Volume 2 ◽

10.1115/msec2011-50220 ◽

2011 ◽

Cited By ~ 7

Author(s):

Hongtao Ding ◽

Yung C. Shin

Keyword(s):

Grain Size ◽

Finite Element ◽

Dislocation Density ◽

Mechanical Behavior ◽

Grain Refinement ◽

Orthogonal Cutting ◽

Pure Titanium ◽

Commercially Pure Titanium ◽

Commercially Pure ◽

Cp Ti

Recently, machining has been exploited as a means for producing ultra-fine grained (UFG) and nanocrystalline microstructures for various metal materials, such as aluminum alloys, copper, stainless steel, titanium and nickel-based super alloys, etc. However, no predictive, analytical or numerical work has ever been presented to quantitatively predict the change of grain sizes during machining. In this paper, a dislocation density-based viscoplastic model is adapted for modeling the grain size refinement mechanism during machining by means of a finite element based numerical framework. A novel Coupled Eulerian-Lagrangian (CEL) finite element model embedded with the dislocation density subroutine is developed to model the severe plastic deformation and grain refinement during a steady-state cutting process. The orthogonal cutting tests of a commercially pure titanium (CP Ti) material are simulated in order to assess the validity of the numerical solution through comparison with experiments. The dislocation density-based material model is calibrated to reproduce the observed material constitutive mechanical behavior of CP Ti under various strains, strain rates and temperatures in the cutting process. It is shown that the developed model captures the essential features of the material mechanical behavior and predicts a grain size of 100–160 nm in the chips of CP Ti at a cutting speed of 10 mm/s.

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