scholarly journals Acceleration of Plasma Nitriding at 550 °C with Rare Earth on the Surface of 38CrMoAl Steel

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1122
Author(s):  
Dongjing Liu ◽  
Yuan You ◽  
Mufu Yan ◽  
Hongtao Chen ◽  
Rui Li ◽  
...  
Keyword(s):  
Rare Earth ◽  
Electron Microscope ◽  
Weight Gain ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Surface Hardness ◽  
Optical Microscope ◽  
Steel Microstructure ◽  
Transmission Electron ◽  
Modified Layer

In order to explore the effect of the addition of rare earth (RE) to a steel microstructure and the consequent performance of a nitrided layer, plasma nitriding was carried out on 38CrMoAl steel in an atmosphere of NH3 at 550 °C for 4, 8, and 12 h. The modified layers were characterized using an optical microscope (OM), a microhardness tester, X-ray diffraction (XRD), a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an electrochemical workstation. After 12 h of nitriding without RE, the modified layer thickness was 355.90 μm, the weight gain was 3.75 mg/cm2, and the surface hardness was 882.5 HV0.05. After 12 h of RE nitriding, the thickness of the modified layer was 390.8 μm, the weight gain was 3.87 mg/cm2, and the surface hardness was 1027 HV0.05. Compared with nitriding without RE, the ε-Fe2-3N diffraction peak was enhanced in the RE nitriding layer. After 12 h of RE nitriding, La, LaFeO3, and a trace amount of Fe2O3 appeared. The corrosion rate of the modified layer was at its lowest (15.089 × 10−2 mm/a), as was the current density (1.282 × 10−5 A/cm2); therefore, the corrosion resistance improved.

LOW-TEMPERATURE NITRIDING BEHAVIOR OF COMPRESSIVE DEFORMED AISI 316Ti AUSTENITIC STAINLESS STEELS

2019 ◽  
Vol 26 (05) ◽  
pp. 1850188 ◽  
Author(s):  
FATIH KAHRAMAN ◽  
GÖKÇE MEHMET GENÇER ◽  
AYÇA D. KAHRAMAN ◽  
COŞKUN YOLCU ◽  
HAYDAR KAHRAMAN
Keyword(s):  
Low Temperature ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Cold Deformation ◽  
Surface Hardness ◽  
Compound Layer ◽  
Optical Microscope ◽  
Layer Growth ◽  
Nitrogen Diffusion ◽  
Undeformed Sample

The effects of compressive cold deformation under the quasi-static loads on the nitride formation, nitride layer growth and surface hardness properties were researched in this study. Martensite structure did not form in AISI 316Ti stainless steel as a result of quasi-static deformation. Diffusion layer did not form in all nitrided samples. Both the deformed and undeformed samples have only compound layer on the surfaces at the low-temperature nitriding conditions (400∘C, 7[Formula: see text]h). According to the X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS) and electron probe microanalysis (EPMA) results, S-phase and chromium nitride (CrN) were formed in the compound layers of the deformed samples. However, CrN did not form in the compound layer of the undeformed sample. The optical microscope (OM) results showed that the compressive cold deformation increased the nitrogen diffusion rate and led to thicker nitrided layer than the undeformed sample under the same plasma-nitriding conditions. All nitrided layers presented higher microhardness values ([Formula: see text][Formula: see text]HV) when compared with the untreated sample hardness. It was also verified that the deformation amount did not affect significantly the nitrided layer hardness.

scholarly journals Low-Temperature Plasma Nitriding of 3Cr13 Steel Accelerated by Rare-Earth Block

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1050
Author(s):  
Yuan You ◽  
Rui Li ◽  
Mufu Yan ◽  
Jihong Yan ◽  
Hongtao Chen ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Mass Gain ◽  
Corrosion Current ◽  
Maximum Increase ◽  
Temperature Plasma ◽  
Pitting Potential ◽  
Modified Layer

The plasma nitriding of 3Cr13 steel occurred at 450 °C for 4, 8 and 12 h in NH3 with and without rare earth (RE). The nitrided layers were characterized using an OM, SEM, TEM, XRD, XPS, microhardness tester and electrochemical workstation. The modified layer, with and without La, are composed of a compound layer and diffusion layer from surface to core. After the addition of La during nitriding, the maximum increase of layer thickness, mass gain and average microhardness was 15.6%, 35.8% and 212.50HV0.05, respectively. With the increase of the proportion of ε-Fe2-3N, the passivation zone of the corrosion resistance curve increases from 2.436 to 3.969 V, the corrosion current density decreases, the corrosion potential and pitting potential both increase, and, consequently, the corrosion resistance is significantly improved. Most of the surface microstructures of the nitrided layer was refined by the addition of La. The presence of La reduces the N content in the modified layer, which accelerates the diffusion of N atoms and, thus, accelerates the nitriding process.

Organoclay-reinforced polyethersulfone-modified epoxy-based hybrid nanocomposites

2011 ◽  
Vol 23 (7) ◽  
pp. 526-534 ◽  
Author(s):  
Yang Wang ◽  
Boming Zhang ◽  
Jinrui Ye
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Electron Microscope ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Hybrid Nanocomposites ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Modified Epoxy ◽  
Scanning Electron

Hybrid nanocomposites were successfully prepared by the incorporation of polyethersulfone (PES) and organoclay into epoxy resin. They had higher fracture toughness than the prepared PES/epoxy blend and organoclay/epoxy nanocomposites. The microstructures of the hybrid nanocomposites were studied. They were comprised of homogeneous PES/epoxy semi-interpenetrating network (semi-IPN) matrices and organoclay micro-agglomerates made up of tactoid-like regions composed of ordered exfoliated organoclay with various orientations. The former was confirmed with dynamic mechanical analysis, scanning electron microscopy and transmission electron microscopy, while the latter was successfully observed with X-ray diffraction measurements, optical microscope, scanning electron microscope and transmission electron microscope. The improvement of their fracture toughness was due to the synergistic toughening effect of the PES and the organoclay and related to their microstructures.

Microstructure of the Acid Welding Slag

2012 ◽  
Vol 249-250 ◽  
pp. 914-917
Author(s):  
Yuan Bin Zhang ◽  
Kai Zhang
Keyword(s):  
Electron Microscope ◽  
Amorphous Matrix ◽  
Low Carbon Steel ◽  
Optical Microscope ◽  
Crystal Phase ◽  
Low Carbon ◽  
Extrusion Press ◽  
Transmission Electron ◽  
Welding Slag ◽  
Welding Electrode

Several E4303 type welding electrodes with different coating compositions were designed and manufactured using TL-25 welding electrode extrusion press. Welding slags of these electrodes were collected after welding on the low carbon steel, then the microstructure and the phase constitutes of the slags were investigated by optical microscope,scan electron microscope (SEM), electron probe microanalyzer (EPMA), Transmission electron microscope (TEM) and X-ray diffraction (XRD). It was indicated that the slags were mainly composed of amorphous matrix and Fe2MnTi3O10 crystal phase. Fe, Mn and Ti were the main elements to form the crystal phase, while Si, Al and Ca were mostly distributed in the amorphous matrix. The formation of the crystal phase in the slag could be controlled by adjusting the amount and the proportion of Fe, Mn and Ti in the welding rod coating.

The Effects of Mechanical Properties on Fatigue Behavior of ECAPed AA7075

2016 ◽  
Vol 35 (3) ◽  
pp. 225-234 ◽  
Author(s):  
Hasan Kaya ◽  
Mehmet Uçar
Keyword(s):  
Electron Microscope ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Angular Pressing ◽  
Four Point Bending ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Hardness Values

AbstractIn this study, the effects of equal channel angular pressing (ECAP) on high-cycle fatigue and fatigue surface morphology of AA7075 have been investigated at a constant temperature (483 K) and the “C” route for four passes at ECAP process. ECAPed and as-received specimens were tested by four-point bending fatigue device. Fatigue tests were carried out by using 100, 120 and 140 MPa strength values. ECAPed specimens were characterized for each pass with optical microscope (OM), scanning electron microscope (SEM), energy-dispersive spectroscope (EDS), transmission electron microscope (TEM), selected area electron diffraction (SAED) and hardness measurements. Fracture surfaces of the specimens were also characterized with SEM. The results show that the highest hardness values (137 HV) and the best fatigue life (5.4 × 107for 100 MPa) were measured in ECAPed four-pass sample. For this reason hardness values and fatigue life were increased with increasing number of severe plastic deformation (SPD) process.

Metallographic Investigation on the Effect of Cryogenic Temperature on Steel Weldments

2014 ◽  
Vol 629 ◽  
pp. 456-460 ◽  
Author(s):  
S. Rasool Mohideen ◽  
Ahmad Zaidi Ahmad Mujahid ◽  
Abdullah Shohaimi ◽  
S. Ravi
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Low Temperatures ◽  
Cryogenic Temperature ◽  
Liquid Nitrogen Temperature ◽  
Optical Microscope ◽  
Low Alloy Steel ◽  
Transmission Electron ◽  
Properties Of Materials

Materials are subjected to low temperatures either intentionally as in the case of cryogenic fuels or non-intentionally as in the case of aerospace environment and are observed to undergo changes in their properties. Microstructural changes are the premier indications of changes in the properties of materials. This paper investigates the effect of cryogenic temperature on the microstructure of low alloy steel weldments. The weldments were subjected to liquid nitrogen temperature of 77K and the microstructures were analyzed using optical microscope and transmission electron Microscope. A distinct change in the microstructure was observed which would reason out the changes in the mechanical properties of weldments.

Study on Precipitation Behavior of High Strength Steel Plate Strengthened Complexly by Titanium and Molybdenum

2011 ◽  
Vol 217-218 ◽  
pp. 812-818
Author(s):  
Hong Bin Wang ◽  
Sheng Li Li ◽  
Li Li ◽  
Peng Cheng Ma
Keyword(s):  
Electron Microscope ◽  
Steel Plate ◽  
High Strength ◽  
Optical Microscope ◽  
Steel Plates ◽  
Transmission Electron ◽  
Cold Rolled ◽  
Hot Rolled ◽  
Hot Rolled Steel ◽  
Energy Disperse Spectroscopy

The precipitation behaviors of hot rolling and cold rolled annealing steel plates strengthened complexly by titanium and molybdenum were studied in the paper. The microstructures and precipitate phases were analyzed using optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) with energy disperse spectroscopy (EDS). The results showed that the coarsening square TiN phase and the fine roundness (Ti,Mo)C phase were precipitated mostly in the hot rolled steel plate. As the finishing temperature decreased and coiling holding time increased, the quantity of fine precipitates increased. And also the fine round precipitates increased, dispersion expanded and shape of the phase being uniformed as the annealing temperature increased. Therefore, the strengthen effects can be improved effectively by a reasonable control toward titanium and molybdenum precipitation behaviors.

TEM Study for Strengthening Mechanisms in Elgiloy

2010 ◽  
Vol 442 ◽  
pp. 268-274 ◽  
Author(s):  
I.N. Qureshi ◽  
S. Rani ◽  
F. Yasmin ◽  
M. Farooque
Keyword(s):  
Electron Microscope ◽  
Cold Work ◽  
Cold Deformation ◽  
Solution Treatment ◽  
Optical Microscope ◽  
Age Hardening ◽  
Solution Treated ◽  
Transmission Electron ◽  
P Transformation ◽  
Cold Worked

Elgiloy is Co based alloy (40wt%Co, 20wt%Cr, 15wt%Ni, 14wt%Fe and 7wt%Mo). It was strengthened by cold work and is capable of additional hardening by aging. The effects of solution treatment, cold working and age-hardening on the microstructure of elgiloy were investigated using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). As rolled strips were solution treated at 1065°C/1hr. These solution treated strips were then reduced 50% by cold rolling. After cold-deformation both є-hcp phase and fcc deformation twins are also considered to coexist at room temperature. The cold worked strips were then age hardened at (450-600)°C. The age hardened strips showed formation of additional є-phase (via α f c c є h c p transformation).

Influence of Direct Lamellarizing and Tempering on Microstructure and Properties of F550 Ship Plate Steel

2013 ◽  
Vol 773 ◽  
pp. 391-396
Author(s):  
Xiao Lin Li ◽  
Qing Wu Cai ◽  
Wei Yu
Keyword(s):  
Electron Microscope ◽  
Impact Energy ◽  
Bainitic Ferrite ◽  
Optical Microscope ◽  
Cleavage Crack ◽  
Plate Steel ◽  
Microstructure And Properties ◽  
Transmission Electron ◽  
Austenite Grains ◽  
The Impact

The effects of quenching at 820 °C 850 °C 940 °C and tempering at 600 °C on microstructure and properties of F550 ship plate steel were studied by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and other experimental methods. The results show that the highest value of the impact energy at-80 °C is 240 J when the steel is quenched at 850 °C and tempered at 600 °C. A full graumber of martensite-austenite (M-A) constituents which distribute in the shape of point-liner or gather among the grains, is larger compared with lamellarizing and tempering. Although the strength of the steel is higher, the value of the impact energy at-80 °C is lower and unstable. After intercritical quenching, the presence of minor ferrite and austenite grains refined could also be helpful to improve the low temperature toughness. Because polygonal ferrite (QF) is small and distributes uniformly between bainitic ferrite lathes acting as beneficial barriers to cleavage crack propagation.

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