scholarly journals In Vitro Corrosion of Titanium Nitride and Oxynitride-Based Biocompatible Coatings Deposited on Stainless Steel

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 710 ◽  
Author(s):  
Iulian Pana ◽  
Viorel Braic ◽  
Mihaela Dinu ◽  
Emile S. Massima Mouele ◽  
Anca C. Parau ◽  
...  
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Xrd Analysis ◽  
304 Stainless Steel ◽  
Cathodic Arc Deposition ◽  
Oxynitride Coatings ◽  
Steel Substrates ◽  
Cathodic Arc ◽  
Bilayer Coatings

The reactive cathodic arc deposition technique was used to produce Ti nitride and oxynitride coatings on 304 stainless steel substrates (SS). Both mono (SS/TiN, SS/TiNO) and bilayer coatings (SS/TiN/TiNO and SS/TiNO/TiN) were investigated in terms of elemental and phase composition, microstructure, grain size, morphology, and roughness. The corrosion behavior in a solution consisting of 0.10 M NaCl + 1.96 M H2O2 was evaluated, aiming for biomedical applications. The results showed that the coatings were compact, homogeneously deposited on the substrate, and displaying rough surfaces. The XRD analysis indicated that both mono and bilayer coatings showed only cubic phases with (111) and (222) preferred orientations. The highest crystallinity was shown by the SS/TiN coating, as indicated also by the largest grain size of 23.8 nm, which progressively decreased to 16.3 nm for the SS/TiNO monolayer. The oxynitride layers exhibited the best in vitro corrosion resistance either as a monolayer or as a top layer in the bilayer structure, making them a good candidate for implant applications.

Modeling of Size Effects on the Flow Stress of Type 304 Stainless Steel and Application in Coining Process

2007 ◽  
Author(s):  
Gap-Yong Kim ◽  
Muammer Koc ◽  
Jun Ni
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Flow Stress ◽  
Size Effect ◽  
Size Effects ◽  
Specimen Size ◽  
304 Stainless Steel ◽  
Length Scales ◽  
Type 304 ◽  
Type 304 Stainless Steel

Application of microforming in various research areas has received much attention due to the increased demand for miniature metallic parts that require mass production. For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/meso-scale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the “feature/specimen size” effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with experiments obtained from previous research and showed a very good agreement. The model was also applied to forming of micro-features by coining. A flow stress model for Type 304 stainless steel taking into consideration the effect of the grain and feature size was developed and implemented into a finite element simulation tool for an accurate numerical analysis. The scaling model offered a simple way to model the size effect down to length scales of a couple of grains and extended the use of continuum plasticity theories to micro/meso-length scales.

scholarly journals Effect of Grain Size on the Friction-Induced Martensitic Transformation and Tribological Properties of 304 Austenite Stainless Steel

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1246
Author(s):  
Bo Mao ◽  
Shuangjie Chu ◽  
Shuyang Wang
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Martensitic Transformation ◽  
Wear Rate ◽  
Tribological Properties ◽  
Friction And Wear ◽  
Wear Behavior ◽  
304 Stainless Steel ◽  
Dry Sliding ◽  
Transformation Behavior

Friction and wear performance of austenite stainless steels have been extensively studied and show a close relationship with the friction-induced martensitic transformation. However, how the grain size and associated friction-induced martensitic transformation behavior affect the tribological properties of austenite steels have not been systematically studied. In this work, dry sliding tests were performed on an AISI 304 stainless steel with a grain size ranging from 25 to 92 μm. The friction-induced surface morphology and microstructure evolution were characterized. Friction-induced martensitic transformation behavior, including martensite nucleation, martensite growth and martensite variant selection and its effect on the friction and wear behavior of the 304 stainless steel were analyzed. The results showed that both the surface coefficient of friction (COF) and the wear rate increase with the grain size. The COF was reduced three times and wear rate was reduced by 30% as the grain size decreased from 92 to 25 μm. A possible mechanism is proposed to account for the effect of grain size on the tribological behavior. It is discussed that austenite steel with refined grain size tends to suppress the amount of friction-induced martensitic transformed and significantly alleviates both the plowing and adhesive effect during dry sliding.

scholarly journals Experimental and Numerical Investigations on Microcoining of Stainless Steel 304

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Gap-Yong Kim ◽  
Muammer Koç ◽  
Jun Ni
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Bulk Material ◽  
High Strength ◽  
304 Stainless Steel ◽  
Feature Size ◽  
Stainless Steel 304 ◽  
Metallic Parts ◽  
Type 304 ◽  
Type 304 Stainless Steel

Increasing demands for miniature metallic parts have driven the application of microforming in various industries. Only a limited amount of research is, however, available on the forming of miniature features in high strength materials. This study investigated the forming of microfeatures in Type 304 stainless steel by using the coining process. Experimental work was performed to study the effects of workpiece thickness, preform shape, grain size, and feature size on the formation of features ranging from 320μmto800μm. It was found that certain preform shapes enhance feature formation by allowing a favorable flow of the bulk material. In addition, a flow stress model for Type 304 stainless steel that took into consideration the effects of the grain and feature sizes was developed to accurately model and better understand the coining process. Weakening of the material, as the grain size increased at the miniature scale, was explained by the Hall–Petch relationship and the feature size effect.

Fracture Resistant and Wear Corrosion Performance of CrN/ZrN Bilayers Deposited onto AISI 420 Stainless Steel

2008 ◽  
Vol 38 ◽  
pp. 63-75 ◽  
Author(s):  
N.A. de Sánchez ◽  
Héctor Enrique Jaramillo Suárez (1) ◽  
Z. Vivas ◽  
W. Aperador ◽  
C. Amaya ◽  
...  
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Impact Resistance ◽  
Grain Sizes ◽  
Aisi 420 ◽  
Average Grain Size ◽  
Afm Analysis ◽  
Corrosive Environments ◽  
Steel Substrates ◽  
Gas Ratio

CrN/ZrN (1, 8, 15, and 30) bilayers were deposited onto AISI 420 steel substrates at 250 °C and 6.6x10-3 mbar with gas ratio Ar/N2 50:3.0 as gas mixture and bias -60V were applied. AFM analysis presented different morphologies, showing that the coatings with 15 bilayers had an average grain size of 49 nm; while the 30-bilayer coating exhibited grain sizes of 99 nm. Coating thicknesses were 3 μm, approximately. The Vickers Test revealed that coatings with 8, 15, and 30 bilayers bore better impact resistance than coatings with 1 bilayer. This result is considered, bearing in mind that in many bilayers propagation of fissures is slower, because the presence of layer inter-phases leads to fissures straying in other directions. Slight corrosion specks are present, but mass loss was around 40 mg. in one bilayer, a higher value than for the coatings with 15 bilayers that was near 18 mg. Homogeneity, grain size, fracture resistance, and corrosion resistance of the coatings with 15 and 30 bilayers are suitable for mechanical applications of these types of coatings, as shown in mechanical measurements. These results indicate that for engineering applications under corrosive environments, the use of these types of bilayer coatings on AISI 420 stainless steel is highly recommended.

In Vitro Bioactivity of AISI 316L Stainless Steel Coated with Hydroxyapatite-Seeded 58S Bioglass

MRS Advances ◽  
2019 ◽  
Vol 4 (57-58) ◽  
pp. 3133-3142 ◽  
Author(s):  
Jorge López-Cuevas ◽  
Juan Carlos Rendón-Angeles ◽  
Juan Méndez-Nonell ◽  
Héctor Barrientos-Rodríguez
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Sol Gel ◽  
Aisi 316L ◽  
In Vitro Bioactivity ◽  
Aisi 316L Stainless Steel ◽  
Gel Technique ◽  
Static Conditions ◽  
Steel Substrates

ABSTRACTAISI 316L stainless steel substrates were coated with hydroxyapatite [HAp, Ca10(PO4)6(OH)2]-seeded 58S bioglass, and then their in vitro bioactivity was evaluated by soaking in a simulated body fluid (SBF). The bioglass was prepared via the sol-gel technique and nanometric HAp single crystals were obtained by hydrothermal synthesis. The coatings had bioglass/HAp weight ratios of 100/0, 90/10 or 80/20. The in vitro bioactivity tests were carried out under static conditions at 37 °C and pH = 7.25, for time periods ranging from 1 to 21 days. The results showed that the HAp-seeding significantly accelerates the formation of a HAp layer at the bioglass-coated steel surface during the bioactivity tests.

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