scholarly journals Surface and Subsurface Analysis of Stainless Steel and Titanium Alloys Exposed to Ultrasonic Pulsating Water Jet

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5212 ◽  
Author(s):  
Jakub Poloprudský ◽  
Alice Chlupová ◽  
Ivo Šulák ◽  
Tomáš Kruml ◽  
Sergej Hloch
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Austenitic Steel ◽  
Surface Profile ◽  
Mechanical Twinning ◽  
Water Jet ◽  
Dislocation Slip ◽  
Ti Alloy ◽  
Near Surface ◽  
Pulsating Water Jet

This article deals with the effect of periodically acting liquid droplets on the polished surfaces of AISI 316L stainless steel and Ti6Al4V titanium alloy. These materials were exposed to a pulsating water jet produced using an ultrasonic sonotrode with an oscillation frequency of 21 kHz placed in a pressure chamber. The only variable in the experiments was the time for which the materials were exposed to water droplets, i.e., the number of impingements; the other parameters were kept constant. We chose a low number of impingements to study the incubation stages of the deformation caused by the pulsating water jet. The surfaces of the specimens were studied using (1) confocal microscopy for characterizing the surface profile induced by the water jet, (2) scanning electron microscopy for detailed surface observation, and (3) transmission electron microscopy for detecting the changes in the near-surface microstructure. The surface described by the height of the primary profile of the surface increased with the number of impingements, and was substantially more intense in the austenitic steel than in the Ti alloy. Irregular surface depressions, slip lines, and short cracks were observed in the Ti alloy, whereas pronounced straight slip bands formed in the austenitic steel. The dislocation density near the surface was measured quantitatively, reaching high values of the order of 1014 m−2 in the austenitic steel and even higher values (up to 3 × 1015 m−2) in the Ti alloy. The origins of the mentioned surface features differed in the two materials: an intense dislocation slip on parallel slip planes for the Ti alloy and mechanical twinning combined with dislocation slip for the austenitic steel.

High Performance Beta Titanium Alloys as a New Material Perspective for Cardiovascular Applications

2012 ◽  
Vol 706-709 ◽  
pp. 578-583 ◽  
Author(s):  
Frédéric Prima ◽  
F. Sun ◽  
Philippe Vermaut ◽  
Thierry Gloriant ◽  
D. Mantovani ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Titanium Alloys ◽  
Metal Ion ◽  
High Performance ◽  
Mechanical Twinning ◽  
High Yield ◽  
Dislocation Slip ◽  
Beta Titanium ◽  
Beta Titanium Alloys

During the last few decades, titanium alloys are more and more popular and developed as biomedical devices because of their excellent biocompatibility, very good combination of mechanical properties and prominent corrosion resistance [1-3]. Recently, a new generation of beta titanium alloys dedicated to biomedical applications has been developed. Based on biocompatible alloying elements such as Ta, Nb, Zr and Mo, these alloys were designed as low modulus alloys [4] or nickel-free superelastic materials [5, 6] mainly for orthopedic or dental applications as osseointegrated implants. Beta type titanium alloys take great advantages from their capacity to display several deformation mechanisms as a function of beta phase stability. Therefore, from low to high beta stability, stress assisted martensitic phase transformation (β-α’’), mechanical twinning or simple dislocation slip can alternatively be observed [7]. As a consequence, a very large range of mechanical properties can be reached, including low apparent modulus, large reversible elastic deformation or high yield stress. Although titanium alloys display now a long history of successful applications in orthopedic and dental devices, none of them have been commercially exploited in the area of coronary stents, despite their superior long term haemocopatibility compared to the 316L stainless steel. However, according to previous researches on the biocompatibility of various metals, the corrosion behavior of stainless steel is dominated by its nickel and chromium components, which may induce redox reaction, hydrolysis and complex metal ion–organic molecule binding reactions, whereas none are observed with titanium [8, 9].

Analysis of the Pulsating Water Jet Maximum Erosive Effect on Stainless Steel

2019 ◽  
pp. 233-241 ◽  
Author(s):  
Dominika Lehocka ◽  
Jiri Klich ◽  
Jan Pitel ◽  
Lucie Krejci ◽  
Zdenek Storkan ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Water Jet ◽  
Pulsating Water Jet ◽  
Erosive Effect

scholarly journals Comparison of advanced techniques for mechanical surface treatment of stainless steel parts

2021 ◽  
Author(s):  
Dmytro Lesyk ◽  
S. Soiama ◽  
B. Mordyuk ◽  
Vitaliy Dzhemelinskyi ◽  
A. Ламікіз
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Surface Treatment ◽  
Surface Hardness ◽  
Water Jet ◽  
Surface Microrelief ◽  
Near Surface ◽  
Treatment Techniques ◽  
Mechanical Surface Treatment ◽  
Mechanical Surface

This work compares various mechanical surface treatment techniques applied to improve the properties of the AISI 304 austenitic stainless steel. Effects of laser shock peening (LSP), water jet cavitation peening (WjCP), water jet shot peening (WjSP), and ultrasonic impact treatment (UIT) on surface roughness, hardness, and residual stress were studied. The results demonstrate that as compared to the untreated specimen (Ra = 3.06 μm), all strain hardening methods demonstrate the decreased surface roughness parameters. The smallest Ra parameter of the wavy regular surface microrelief is formed after the ultrasonic treatment. The surface hardness (22.1 HRC5) was respectively increased by 30.7%, 38.4%, 69.6%, and 73.2% after the LSP, WjCP, WjSP, and UIT treatments. All peening techniques induced compressive residual stresses (ranged from –377 MPa to –693 MPa) in the near-surface layer. It is assumed that used treatments can increase wear/corrosion resistance and fatigue life in the studied steel.

Shock consolidation of Ni-Ti alloy powder

1986 ◽  
Vol 44 ◽  
pp. 430-431
Author(s):  
Naresh N. Thadhani ◽  
Thad Vreeland ◽  
Thomas J. Ahrens
Keyword(s):  
Alloy Powder ◽  
Amorphous Material ◽  
Ti Alloy ◽  
Two Phase ◽  
Near Surface ◽  
Optical Micrograph ◽  
Shock Compaction ◽  
Powder Particles ◽  
Ti Powder ◽  
Rapidly Solidified

A spherically-shaped, microcrystalline Ni-Ti alloy powder having fairly nonhomogeneous particle size distribution and chemical composition was consolidated with shock input energy of 316 kJ/kg. In the process of consolidation, shock energy is preferentially input at particle surfaces, resulting in melting of near-surface material and interparticle welding. The Ni-Ti powder particles were 2-60 μm in diameter (Fig. 1). About 30-40% of the powder particles were Ni-65wt% and balance were Ni-45wt%Ti (estimated by EMPA).Upon shock compaction, the two phase Ni-Ti powder particles were bonded together by the interparticle melt which rapidly solidified, usually to amorphous material. Fig. 2 is an optical micrograph (in plane of shock) of the consolidated Ni-Ti alloy powder, showing the particles with different etching contrast.

Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

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