Controlled Nanocrystallization of NiTi Shape Memory Alloy by Laser Shock Peening

2011 ◽  
Author(s):  
Chang Ye ◽  
Gary J. Cheng
Keyword(s):  
Electron Microscopy ◽  
High Strain ◽  
Laser Shock Peening ◽  
Niti Shape Memory Alloy ◽  
Deformation Characteristics ◽  
Laser Shock ◽  
Transmission Electron ◽  
High Strain Rate Deformation ◽  
Shock Peening ◽  
Different Grain Size

In this paper, partial amorphization of NiTi alloys by laser shock peening (LSP) is reported. The microstructure of NiTi after LSP was characterized by transmission electron microscopy (TEM). The amorphization mechanism was discussed in light of the high strain rate deformation characteristics of LSP. With subsequent controlled annealing after LSP, nanostructure with different grain size distribution was achieved.

A Study of the Microstructure and Hardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr by Laser Shock Peening

2011 ◽  
Vol 84-85 ◽  
pp. 471-475 ◽  
Author(s):  
Wei Feng He ◽  
Yu Qin Li ◽  
Xiang Fan Nie ◽  
Rui Jun Liu ◽  
Qi Peng Li
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Titanium Alloy ◽  
High Strain ◽  
The Other ◽  
Laser Shock Peening ◽  
Microscopic Structure ◽  
Laser Shock ◽  
High Strain Rate Deformation ◽  
Shock Peening

In this paper, the microstructure and hardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy with and without laser shock peening (LSP) were examined and compared. The titanium alloy samples were laser shock peened with different layers at the same power density. The microscopic structure after LSP are tested and analyzed by SEM and TEM. The results indicated that LSP changed the microstructure evidently. After 3 layers laser shock peening, there are nanocrystallization in the LSP zone. The shock wave provided high strain rate deformation and generated high-density dislocations in the material. Multiple severe plastic deformation caused by 3 to 5 LSP layers helped to rearrange the resultant dislocation, to form dislocation networks, leading to the formation of nanocrystallites. On the other hand, the microhardness across the polished surfaces of the titanium materials with and without LSP was measured. It is obvious that the laser shock peening improved the microhardness of the Ti-5Al-2Sn-2Zr-4Mo-4Cr for about 16% at the surface, and the affected depth is about 300 microns from the surface.

Effects of Temperature on Laser Shock Induced Plastic Deformation: The Case of Copper

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Chang Ye ◽  
Gary J. Cheng
Keyword(s):  
Plastic Deformation ◽  
Elevated Temperature ◽  
Deformation Behavior ◽  
High Strain ◽  
Fem Simulation ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
High Strain Rate Deformation ◽  
Effects Of Temperature ◽  
Shock Peening

Laser shock induced plastic deformation has been used widely, such as laser shock peening (LSP), laser dynamic forming (LDF), and laser peen forming. These processes have been extensively studied both numerically and experimentally at room temperature. Recently, it is found that at elevated temperature, laser shock induced plastic deformation can generate better formability in LDF and enhanced mechanical properties in LSP. For example, warm laser shock peening leads to improved residual stress stability and better fatigue performance in aluminum alloys. There is a need to investigate the effects of elevated temperature on deformation behavior of metallic materials during shock induced high strain rate deformation. In this study, LSP of copper are selected to systematically study the effects of elevated temperature in shock induced high strain rate deformation. Finite element modeling (FEM) is used to predict the deformation behavior. The FEM simulation results of surface profile and residual stress distribution after LSP are validated by experimental results. The validated FEM simulation is used to study the effects of temperature on the plastic deformation behaviors during LSP, such as plastic affected zone, stress/strain distribution, and energy absorption.

scholarly journals The Microstructure and Properties of Laser Shock Peened CMSX4 Superalloy

2021 ◽  
Author(s):  
Magdalena Rozmus-Górnikowska ◽  
Jan Kusiński ◽  
Łukasz Cieniek ◽  
Jerzy Morgiel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Layer ◽  
Chemical Elements ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Localized Deformation ◽  
Gamma Prime ◽  
Transmission Electron ◽  
Shock Peening

AbstractThe influence of laser shock peening on the surface morphology and microstructure of single-crystal CMSX4 nickel-based superalloy was investigated by optical profilometry and atomic force microscopy, scanning and transmission electron microscopy as well as scanning-transmission electron microscopy in high-angle annular dark-field mode. Maps of chemical elements distribution in the laser-affected areas were determined using energy-dispersive X-ray spectroscopy. Furthermore, after the LSP, nanohardness tests were conducted on the cross section of the treated samples as well as the untreated material. Laser shock peening caused an ablation and melting of the surface layer and hence enlarged the surface roughness. Beneath the surface, in the laser shock-peened areas, severe distortion of the regular $$ {\gamma \mathord{\left/ {\vphantom {\gamma {\gamma^{\prime}}}} \right. \kern-0pt} {\gamma^{\prime}}} $$ γ / γ ′ microstructure was observed. In the surface layer, down to about 15 μm, shear bands of localized deformation were formed. Moreover, the result showed that the average nano-hardness value was obviously increased in the laser-treated region.

scholarly journals Improvement of Fatigue Life of GH3039 Superalloy by Laser Shock Peening

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3849
Author(s):  
Yang Tang ◽  
MaoZhong Ge ◽  
Yongkang Zhang ◽  
Taiming Wang ◽  
Wen Zhou
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Surface Profile ◽  
Optical Microscope ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Transmission Electron ◽  
Before And After ◽  
Shock Peening ◽  
Improve Fatigue

In order to improve fatigue life of GH3039 superalloy, GH3039 superalloy sheets were treated by laser shock peening (LSP). The microstructure of GH3039 superalloy before and after LSP was characterized using an optical microscope, transmission electron microscope (TEM), and X-ray diffractometer. The fatigue life of the samples with and without LSP was investigated by fatigue experiments. Moreover, surface profile and residual stress were also examined. Experimental results indicated that the grains in the surface layer of the LSP sample were remarkably refined and reached the nanometer scale. The average surface roughness increased from 0.024 μm to 0.19 μm after LSP. The average fatigue life of the laser treated samples was 2.01 times larger than that of the untreated specimens. Additionally, mathematical statistical analysis confirms that LSP has a significant influence on the fatigue life of GH3039 superalloy. The improvement of fatigue life for the laser processed GH3039 superalloy was mainly attributed to compressive residual stress and grain refinement generated by LSP.

scholarly journals Mechanical Properties of NiTi Shape Memory Alloy Processed by Laser Shock Peening

2013 ◽  
Vol 40 (11) ◽  
pp. 1103002
Author(s):  
夏伟光 Xia Weiguang ◽  
吴先前 Wu Xianqian ◽  
魏延鹏 Wei Yanpeng ◽  
黄晨光 Huang Chenguang ◽  
王曦 Wang Xi
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Laser Shock Peening ◽  
Niti Shape Memory Alloy ◽  
Laser Shock ◽  
Shock Peening

FE Modeling and Analysis of Patterning Micron Surface Structures by Laser Shock Peening

2007 ◽  
Author(s):  
A. W. Warren ◽  
Y. B. Guo
Keyword(s):  
Mechanical Behavior ◽  
High Strain ◽  
Shock Pressure ◽  
Surface Structures ◽  
Laser Shock Peening ◽  
Strain Rates ◽  
Laser Shock ◽  
High Strain Rates ◽  
Direct Input ◽  
Shock Peening

Laser shock peening (LSP) is a potential fabrication process to pattern micron surface structures. The purpose of this paper is to model 3D shock pressure and dynamic mechanical behavior at high strain rates during laser patterning process. The 3D shock pressure was modeled using a user defined subroutine. The mechanical behavior at high strain rates is predicted by the Bammann, Chiesa, and Johnson (BCJ) model. A 3D FEA model of microscale LSP was created using the developed loading and material subroutines. For comparison, a direct input of measured material properties was also used. The results show that decreasing pulse time shifts the maximum transient stress from the surface to the subsurface. The rapid loading causes increased magnitudes of compressive stress throughout the depth. The BCJ model predicts higher stresses than the direct input method.

Plastic Deformation in Silicon Crystal Induced by Heat-Assisted Laser Shock Peening

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Gary J. Cheng ◽  
M. Cai ◽  
Daniel Pirzada ◽  
Maxime J.-F. Guinel ◽  
M. Grant Norton
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Compressive Residual Stress ◽  
Silicon Crystal ◽  
Brittle Materials ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Electron Backscattered Diffraction ◽  
Transmission Electron ◽  
Shock Peening

The response of solid to shock compression has been an interesting topic for more than a century. The present work is the first attempt to experimentally show that plastic deformation can be generated in brittle materials by a heat-assisted laser shock peening process, using silicon crystal as a sample material. Strong dislocation activity and large compressive residual stress are induced by this process. The dislocation structure is characterized with transmission electron microscopy and electron backscattered diffraction. The residual stress is measured using Raman scattering. This work presents a fundamental base for the application of laser shock peening in brittle materials to generate large compressive residual stress and plastic deformation for better mechanical properties, such as fatigue life and fracture toughness.

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