scholarly journals Investigations into the Improvement of the Mechanical Properties of Ti-5Al-4Mo-4Cr-2Sn-2Zr Titanium Alloy by Using Low Energy Laser Peening without Coating

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1398
Author(s):  
Dingyuan Xue ◽  
Yang Jiao ◽  
Weifeng He ◽  
Xiaojun Shen ◽  
Yangjun Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Strength ◽  
Dynamic Equilibrium ◽  
Laser Energy ◽  
Strengthening Mechanism ◽  
Laser Peening ◽  
Micro Hardness ◽  
Laser Peening Without Coating

Mechanical properties, such as residual stress, micro-hardness and fatigue performance, of the Ti-5Al-4Mo-4Cr-2Sn-2Zr titanium alloy were improved via the laser peening without coating (LPwC) with a water-penetrable wavelength of 532 nm and pulse duration of 10 ns. In this paper, three kinds of laser energy, namely 85, 110 and 160 mJ were used to process the samples. The titanium alloy samples were also peened with different impact times (1, 3 or 5 impacts) at the energy of 85 mJ. The micro-hardness and residual stress distribution results provided that LPwC can introduce compressive residual stress (CRS) and also induce hardening of the target materials. Further, micro-hardness and CRS showed the increasing trends when the laser impact times increased. However, the CRS and micro-hardness decreased while the laser energy increased from 110 to 160 mJ, which was attributed to the dynamic equilibrium between the thermal and mechanical effects of LPwC. High cycle fatigue strength of the titanium alloy was significantly improved from 360 to 490.3 MPa after three impacts LPwC. The strengthening mechanism of fatigue strength subjected to LPwC was a combined effect between the laser-induced CRS and the high-density dislocations.

Effect of Laser Peening on Residual Stress and Micro-Hardness of TC4 Titanium Alloy

2013 ◽  
Vol 341-342 ◽  
pp. 246-250
Author(s):  
Hong Chao Qiao ◽  
Ji Bin Zhao ◽  
Yi Xiang Zhao ◽  
Lun Li
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Layer Thickness ◽  
Pulse Energy ◽  
Work Piece ◽  
Laser Peening ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Hardness Tester ◽  
Tc4 Titanium Alloy

Laser peening offers potential advantages over conventional peen technologies in terms of the depth of the residual stresses that can be induced, and improvements in surface micro-hardness. The present study was undertaken to understand the effect of laser penning on the properties of titanium alloy, a TC4 titanium alloy work-piece was processed with ND: YAG laser with the wavelength of 1064 nm, pulse energy of 0-10J and pulse width of 12ns, and micro-hardness and residual stress for different laser peening parameters were examined and analyzed by micro-hardness tester and X-ray diffraction. Results are presented and discussed of the residual stress profiles and the micro-hardness profiles, The experimental results show that the satisfying laser peening appearance can be achieved when the pulse energy was 6J, water tamping layer thickness was 1.8mm and ablative layer thickness was 100μm, surface micro-hardness increased by up to 33% and the compressive residual stress on the surface of laser shocked area reached up to-327.8MPa, laser peening improved hardness and residual stress of titanium alloy significantly. The experiment results show that the effect of laser peening was evidently.

Effect of Laser Peening on Residual Stress and Micro-Hardness of TC4 Titanium Alloy

2013 ◽  
Vol 710 ◽  
pp. 208-212
Author(s):  
Hong Chao Qiao ◽  
Ji Bin Zhao ◽  
Yi Xiang Zhao ◽  
Lun Li
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Layer Thickness ◽  
Pulse Energy ◽  
Work Piece ◽  
Laser Peening ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Hardness Tester ◽  
Tc4 Titanium Alloy

Laser peening offers potential advantages over conventional peen technologies in terms of the depth of the residual stresses that can be induced, and improvements in surface micro-hardness. The present study was undertaken to understand the effect of laser penning on the properties of titanium alloy, a TC4 titanium alloy work-piece was processed with ND: YAG laser with the wavelength of 1064 nm, pulse energy of 0-10J and pulse width of 12ns, and micro-hardness and residual stress for different laser peening parameters were examined and analyzed by micro-hardness tester and X-ray diffraction. Results are presented and discussed of the residual stress profiles and the micro-hardness profiles, The experimental results show that the satisfying laser peening appearance can be achieved when the pulse energy was 6J, water tamping layer thickness was 1.8mm and ablative layer thickness was 100μm, surface micro-hardness increased by up to 33% and the compressive residual stress on the surface of laser shocked area reached up to-327.8MPa, laser peening improved hardness and residual stress of titanium alloy significantly. The experiment results show that the effect of laser peening was evidently.

scholarly journals Mechanical Properties Study of Fe-Mn-Si Shape Memory Alloys Welding Seam Formed by Laser Welding with Filler Powder

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1454 ◽  
Author(s):  
Heng Ju ◽  
Chengxin Lin ◽  
Yun Tian ◽  
Zhijie Liu ◽  
Huiling Jiang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Laser Welding ◽  
Strengthening Mechanism ◽  
304 Stainless Steel ◽  
Distribution Law ◽  
Welding Seam ◽  
Filler Powder

To reduce the residual stress and improve the fatigue property of the laser weldment by using the stress self-accommodation characteristic of Fe-Mn-Si shape memory alloys (SMAs), a Fe15Mn5Si12Cr6Ni memory alloy welding seam was formed inside 304 stainless steel by laser welding with filler powder. The combination of the hole-drilling method and the ANSYS software was used to research the distribution law of residual stress inside the laser welding specimen. The fatigue strength of the laser welded specimens with the Fe-Mn-Si SMAs welding seam (experimental materials) and 304 stainless steel welding seam (comparative materials) was measured by cycle bending fatigue test. The microhardness of the welding specimens was measured by the microhardness tester. The thermodynamic model of the laser welding process and the phase transition crystallography of Fe-Mn-Si SMAs were evaluated to analyze the strengthening mechanism of the mechanical properties in the experimental materials. The results show that the distribution law for residual stress in the experiment and simulation are consistent. The experimental materials possess low residual stress, high fatigue strength and high microhardness. The strengthening mechanism for mechanical properties is the welding residual stress-induced γ→ε martensitic transformation inside the experimental materials, which causes the tensile plastic strain of the welding seam to resist residual compression strain, and the residual stress, as the transition driving force, is released in shear processing.

The Effects of Machined Workpiece Surface Integrity on the Fatigue Life of TC21 Titanium Alloy

2012 ◽  
Vol 503-504 ◽  
pp. 382-389 ◽  
Author(s):  
Dong Xing Du ◽  
Dao Xin Liu ◽  
Yu Feng Sun ◽  
Jin Gang Tang ◽  
Xiao Hua Zhang
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Surface Integrity ◽  
Surface Profile ◽  
Fatigue Properties ◽  
Profile Measurement ◽  
Micro Hardness ◽  
Finish Turning ◽  
Rough Turning

In this paper, the influence of different machining methods (including rough turning, finish turning, and longitudinal polishing after finish turning) on rotating bending fatigue properties of TC21 which belonged to a new ultra high strength titanium alloy was studied. The influence of machining methods on surface integrity of TC21 titanium alloy was measured by using surface profile measurement, scanning electron microscopy, metallography microscope, micro-hardness instrument and X-ray diffraction residual stress analyzer. And fatigue fractography of specimens was further investigated. Then the mechanism of fatigue resistance which was affected by machining surface integrity was discussed. The results indicated that the fatigue life of finish turning and longitudinal polishing after finish turning was increased 3.96 times and 17.34 times compared with rough turning, respectively. The machining surface integrity had important influence on fatigue property of TC21 titanium alloy, which caused by the differences of surface roughness and texture as the dominant factors, and then the variation in surface micro-hardness, metallographic microstructure and the surface residual stress were not the main factors on three above-mentioned machining methods. By using longitudinal polishing after finish turning processing method for preparation of TC21 titanium alloy parts could ensure good surface integrity and excellent fatigue performance.

Experimental Study on Residual Stresses of Al2O3 Coating by Laser Re-Melting

2010 ◽  
Vol 431-432 ◽  
pp. 446-449
Author(s):  
De Jun Kong ◽  
Kai Yu Luo ◽  
Hong Miao
Keyword(s):  
Residual Stress ◽  
Experimental Study ◽  
Tensile Stress ◽  
Residual Stresses ◽  
High Power ◽  
Bonding Strength ◽  
Strengthening Mechanism ◽  
Al2o3 Coating ◽  
Micro Hardness ◽  
Continuous Co2 Laser

The surface of Al2O3 coating sprayed on 40Cr substrate was re-melted with high power continuous CO2 laser, and its micro-hardness and residual stresses were measured, respectively. The strengthening mechanism of Al2O3 coating by laser re-melting was analyzed and discussed. The experimental results shown that the surface of Al2O3 coating by laser re-melting is neat and smooth, and its compositions are even, its structures are compact, and Al2O3 coating is evenly distributed in its surface with grain forms, and its micro-hardness increases about 200%; Residual stress of Al2O3 coating by laser re-melting is changed into compressive stress from tensile stress, which is benefit to improving bonding strength of coating-substrate interface.

scholarly journals Influence of Nd:YAG Laser Energy on Mechanical properties of Nitriding Steel

2020 ◽  
Vol 23 (2) ◽  
pp. 187-193
Author(s):  
Ansam Abdul Jabbar Aziz ◽  
Enass A. Khalid ◽  
Abbas S. Alwan
Keyword(s):  
Mechanical Properties ◽  
Wear Rate ◽  
Surface Treatment ◽  
Nd:Yag Laser ◽  
Laser Energy ◽  
Thermochemical Treatment ◽  
Surface Heat ◽  
Laser Surface ◽  
Micro Hardness ◽  
Laser Surface Treatment

Desired mechanical properties like microstructure, micro hardness and wear resistance are the key parameters for which low carbon steel (AISI 1006) are widely selected. Surface heat treatment applied to improve these properties; traditionally surface heat treatments like induction hardening, in recent time’s laser surface hardening. In this work, thermochemical treatment (liquid nitriding) by using mixture from 61% NaCN, 15% K2CO3 and 24% KCL and followed by Nd:YAG laser surface treatment was done . The laser parameter were energy (0.89, 2, 4 and 9) J, spot diameter (0.790 ,0.33, 0.283 and 0.224) mm, pulses duration (1, 2.33, 4.47 and 9.87) ms with  fix wavelength 1604nm. Laser surface treatment cycle was melting the layer surface, holding and rapid cooling in air medium.  Optical microscopy (OM) and scanning electron microscope (SEM) has been used to study the microstructures and cross-sectional of molted and heat affected zones respectively. The wear test was done to measure the wear rate by using pin -on-disk principles were satisfied. The result shown that increasing in laser energy effects to increase in the area of melted and heat affected zones of nitriding steel. Also increasing in laser energy led to increase micro hardness about 61%, while wear rate decrease about 40 % and increased depth of molted zone.

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