scholarly journals A Novel Decarburizing-Nitriding Treatment of Carburized/through-Hardened Bearing Steel towards Enhanced Nitriding Kinetics and Microstructure Refinement

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 112
Author(s):  
Fuyao Yan ◽  
Jiawei Yao ◽  
Baofeng Chen ◽  
Ying Yang ◽  
Yueming Xu ◽  
...  
Keyword(s):  
Surface Engineering ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Metallographic Analysis ◽  
Material Surface ◽  
Low Carbon ◽  
High Carbon ◽  
Softening Effect ◽  
Microstructure Refinement ◽  
Bearing Steels

Decarburization is generally avoided as it is reckoned to be a process detrimental to material surface properties. Based on the idea of duplex surface engineering, i.e., nitriding the case-hardened or through-hardened bearing steels for enhanced surface performance, this work deliberately applied decarburization prior to plasma nitriding to cancel the softening effect of decarburizing with nitriding and at the same time to significantly promote the nitriding kinetics. To manifest the applicability of this innovative duplex process, low-carbon M50NiL and high-carbon M50 bearing steels were adopted in this work. The influence of decarburization on microstructures and growth kinetics of the nitrided layer over the decarburized layer is investigated. The metallographic analysis of the nitrided layer thickness indicates that high carbon content can hinder the growth of the nitrided layer, but if a short decarburization is applied prior to nitriding, the thickness of the nitrided layer can be significantly promoted. The analysis of nitriding kinetics shows that decarburization reduces the activation energy for nitrogen diffusion and enhances nitrogen diffusivity. Moreover, the effect of decarburization in air can promote surface microstructure refinement via spinodal decomposition during plasma nitriding.

The Influence of Plasma Nitriding Period on Nitrided Layers Thickness

2016 ◽  
Vol 258 ◽  
pp. 395-398 ◽  
Author(s):  
Ondrej Pilch ◽  
Vojtěch Hruby
Keyword(s):  
Optical Microscopy ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Surface Hardness ◽  
Experimental Methods ◽  
Nitriding Process ◽  
Material Surface ◽  
Hardness Testing ◽  
Surface Layers ◽  
Cross Sectional

The plasma nitriding as a technology for finishing of material surface layers was carried out on selected material. The effect of plasma nitriding conditions on the thickness and hardness of nitrided layer was investigated. The influence of plasma nitriding period on the thickness of the plasma nitrided layers was comprehensively assessed on the C55 steels. Plasma nitriding was carried out on selected material at 500 °C under 280 Pa with a mixture atmosphere of H2 and N2 in the plasma nitriding equipment. The period of the plasma nitriding process was changeable from 5 to 20 hours. Measurements of the properties of nitrided layers of selected material were solved by using experimental methods in accordance with standards. The samples were characterized by GDOES spectrometry, optical microscopy, and hardness testing. The depths of the plasma nitriding layers were also detected using cross-sectional microhardness profiles. Relation between plasma nitriding period and a thickness of a nitrided layer was explained and has shown that microhardness and surface hardness of mentioned samples were significantly increased.

Plasma Ion Nitriding of Low Carbon Stainless Maraging Steel

2015 ◽  
Vol 830-831 ◽  
pp. 675-678
Author(s):  
M. Agilan ◽  
T. Venkateswran ◽  
D. Sivakumar ◽  
Bhanu Pant
Keyword(s):  
Maraging Steel ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Surface Hardness ◽  
Case Depth ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Ion Nitriding ◽  
X Ray ◽  
Stainless Maraging Steel

Low carbon stainless maraging steel (0.03%C-12%Cr-10Ni-0.6Mo-0.2Ti) is being used widely for various components of the aerospace engines. To improve the wear resistance of the steel various surface hardening processes are being utilized to improve the surface hardness above 900HV. In this present research, plasma nitriding was carried out at two different temperatures of 450 °C and 475 °C for the holding duration of 10 hrs. Temperature of the nitrding process was ensured below the ageing temperature (500 °C) of the steel to avoid lowering of mechanical properties. Effect of plasma nitriding parameters on the surface hardness, case depth, microstructure and phases present in the nitrided layer were investigated in detail using microhardness analysis across the nitrided layer, X-ray diffraction (XRD), optical microscopy and scanning electron microscopy (SEM). It was observed that increase in nitriding temperature increased the surface hardness and case depth. In addition, the presence of Fe3N and Fe4N phases in the nitrided layer were observed using X-ray diffraction technique.

A high-Voltage electron microscopical investigation of interphase precipitation in high-carbon copper-bearing steels

1990 ◽  
Vol 48 (4) ◽  
pp. 204-205
Author(s):  
G. N. Fourlaris ◽  
A.J. Baker
Keyword(s):  
Low Alloy Steels ◽  
Low Carbon ◽  
High Carbon ◽  
Ferrous Alloys ◽  
Interphase Precipitation ◽  
Voltage Electron ◽  
Bearing Steels ◽  
Proeutectoid Ferrite ◽  
Interphase Boundaries ◽  
Alloy Steels

It is well established that in certain types of low alloy steels the precipitation of alloy carbides occurring on the moving ferrite-austenite interphase boundaries accompanies the growth of proeutectoid ferrite. In other ferrous alloys containing copper or gold but carbon free, the precipitation of discrete particles or particles with fibrous morphology, on the moving ferrite-austenite interphase boundaries has also been observed. In order to describe these phenomena the term interphase precipitation has been used. Although considerable research has been carried out, especially in low carbon copper-bearing steels, interphase precipitation of ε-Cu in high carbon copper steels is not yet fully understood. In this study, high carbon copper-bearing steels were used to assess the interphase precipitation characteristics in the various microconstituents of these steels.

Precipitation at the transformation interface of pearlite in steel

1990 ◽  
Vol 48 (4) ◽  
pp. 912-913
Author(s):  
F. A. Khalid ◽  
D. V. Edmonds
Keyword(s):  
Thin Foil ◽  
Carbon Steels ◽  
Model Alloy ◽  
Low Carbon ◽  
High Carbon ◽  
Growth Interface ◽  
Medium Carbon ◽  
Interphase Precipitation ◽  
Solution Treated ◽  
Wide Range

The austenite/pearlite growth interface in a model alloy steel (Fe-1lMn-0.8C-0.5V nominal wt%) is being studied in an attempt to characterise the morphology and mechanism of VC precipitation at the growth interface. In this alloy pearlite nodules can be grown isothermally in austenite that remains stable at room temperature thus facilitating examination of the transformation interfaces. This study presents preliminary results of thin foil TEM of the precipitation of VC at the austenite/ferrite interface, which reaction, termed interphase precipitation, occurs in a number of low- carbon HSLA and microalloyed medium- and high- carbon steels. Some observations of interphase precipitation in microalloyed low- and medium- carbon commercial steels are also reported for comparison as this reaction can be responsible for a significant increase in strength in a wide range of commercial steels.The experimental alloy was made as 50 g argon arc melts using high purity materials and homogenised. Samples were solution treated at 1300 °C for 1 hr and WQ. Specimens were then solutionised at 1300 °C for 15 min. and isothermally transformed at 620 °C for 10-18hrs. and WQ. Specimens of microalloyed commercial steels were studied in either as-rolled or as- forged conditions. Detailed procedures of thin foil preparation for TEM are given elsewhere.

Influence of Cementite Particle Size Distribution on Machinability and Tool Life of High Carbon Cr-bearing Steels

1998 ◽  
Vol 84 (5) ◽  
pp. 387-392 ◽  
Author(s):  
Takashi INOUE ◽  
Yuzo HOSOI ◽  
Koe NAKAJIMA ◽  
Hiroyuki TAKENAKA ◽  
Tomonori HANYUDA
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Tool Life ◽  
Cementite Particle ◽  
High Carbon ◽  
Bearing Steels

scholarly journals Interfacial Phenomena and Inclusion Formation Behavior at Early Melting Stages of HCFeCr and LCFeCr Alloys in Liquid Iron

2021 ◽  
Author(s):  
Yong Wang ◽  
Andrey Karasev ◽  
Joo Hyun Park ◽  
Wangzhong Mu ◽  
Pär G. Jönsson
Keyword(s):  
Liquid Iron ◽  
Diffusion Zone ◽  
Early Stage ◽  
Interfacial Phenomena ◽  
Solid Alloy ◽  
Low Carbon ◽  
High Carbon ◽  
Free Zone ◽  
Formation Behavior ◽  
Predetermined Time

AbstractChromium is normally added to liquid alloy in the form of different grades of ferrochromium (FeCr) alloys for the requirement of different alloy grades, such as stainless steels, high Cr cast iron, etc.. In this work, inclusions in two commercially produced alloys, i.e., high-carbon ferrochromium (HCFeCr) and low-carbon ferrochromium (LCFeCr) alloys, were investigated. The FeCr alloy/liquid iron interactions at an early stage were investigated by inserting solid alloy piece into contact with the liquid iron for a predetermined time using the liquid-metal-suction method. After quenching these samples, a diffusion zone between the alloys and the liquid Fe was studied based on the microstructural characterizations. It was observed that Cr-O-(Fe) inclusions were formed in the diffusion zone, FeOx inclusions were formed in the bulk Fe, and an “inclusion-free” zone was detected between them. Moreover, it was found that the HCFeCr was slowly dissolved, but LCFeCr alloy was rapidly melted during the experiment. The dissolution and melting behaviors of these two FeCr alloys were compared and the mechanism of the early-stage dissolution process of FeCr alloys in the liquid Fe was proposed.

scholarly journals Carbon Emission Governance Zones at the County Level to Promote Sustainable Development

Land ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 197
Author(s):  
He Zhang ◽  
Jingyi Peng ◽  
Dahlia Yu ◽  
Lie You ◽  
Rui Wang
Keyword(s):  
Sustainable Development ◽  
Carbon Emission ◽  
Total Carbon ◽  
Small Scale ◽  
County Level ◽  
Low Carbon ◽  
High Carbon ◽  
Governance System ◽  
Medium Carbon ◽  
Indicator Evaluation

Low-carbon governance at the county level has been an important issue for sustainable development due to the large contributions to carbon emission. However, the experiences of carbon emission governance at the county level are lacking. This paper discusses 5 carbon emission governance zones for 1753 counties. The zoning is formed according to a differentiated zoning method based on a multi-indicator evaluation to judge if the governance had better focus and had formulated a differentiated carbon emission governance system. According to zoning results, there is 1 high-carbon governance zone, 2 medium-carbon governance zones, and 2 low-carbon zones. The extensive high-carbon governance zone and medium-carbon zones are key governance areas, in which the counties are mainly located in the northern plain areas and southeast coastal areas and have contributed 51.88% of total carbon emissions. This paper proposes differentiated governance standards for each indicator of the 5 zones. The differentiated zoning method mentioned in this paper can be applied to other governance issues of small-scale regions.

scholarly journals Hard Protective Layers on Forging Dies—Development and Applications

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 376
Author(s):  
Jerzy Smolik
Keyword(s):  
Surface Engineering ◽  
Nitrided Layer ◽  
Research Work ◽  
Operating Conditions ◽  
Pvd Coating ◽  
Precise Diagnosis ◽  
Coating Type ◽  
Important Quality ◽  
Material Solution ◽  
Hybrid Layers

The article presents a summary of many years of activities in the area of increasing the durability of forging dies. The results of comprehensive research work on the analysis of the destructive mechanisms of forging dies and the possibility of increasing their durability with the use of modern surface engineering methods are presented. Great possibilities in terms of shaping operational properties of forging dies by producing hybrid layers of the “Nitrided Layer + PVD Coating” (NL + PVD coating) type were confirmed. An analysis of changes in forging dies durability under various operating conditions was performed, i.e., forging—die—forging press—pressures. It has been shown that the variety of parameters of the forging process, including forgings’ geometry and weight, materials, precision, pressures applied, and, what is very important, quality of machines, makes it very difficult to compare the effectiveness of various PVD coating solutions in the process of increasing the durability of forging dies. Hybrid layers of the “NL + PVD coating” type create great possibilities in shaping the operational properties of tools and machine elements. However, in each application a precise diagnosis of the wear mechanism and the design of an individual PVD coating material solution is required.

Nitriding of yttria-stabilized zirconia in atmospheric pressure microwave plasma

2009 ◽  
Vol 24 (6) ◽  
pp. 2021-2028 ◽  
Author(s):  
R. Milani ◽  
R.P. Cardoso ◽  
T. Belmonte ◽  
C.A. Figueroa ◽  
C.A. Perottoni ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Microwave Plasma ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Zirconium Nitride ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia ◽  
X Ray ◽  
Yttria Partially Stabilized Zirconia

High temperature plasma nitriding of yttria-partially-stabilized zirconia in atmospheric pressure microwave plasma was investigated. The morphological, mechanical, and physicochemical characteristics of the resulting nitrided layer were characterized by different methods, such as optical and scanning electron microscopy, microindentation, x-ray diffraction, narrow resonant nuclear reaction profiling, secondary neutral mass spectrometry, and x-ray photoelectron spectroscopy, aiming at investigating the applicability of this highly efficient process for nitriding of ceramics. The structure of the plasma nitrided layer was found to be complex, composed of tetragonal and cubic zirconia, as well as zirconium nitride and oxynitride. The growth rate of the nitrided layer, 4 µm/min, is much higher than that obtained by any other previous nitriding process, whereas a typical 50% increase in Vickers hardness over that of yttria-partially-stabilized zirconia was observed.

scholarly journals Combined Use of Surface Texturing, Plasma Nitriding and DLC Coating on Tool Steel

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 201
Author(s):  
Elisangela Aparecida dos Santos de Almeida ◽  
Julio Cesar Giubilei Milan ◽  
César Edil da Costa ◽  
Cristiano Binder ◽  
José Daniel Biasoli de Mello ◽  
...  
Keyword(s):  
Surface Topography ◽  
Tool Steel ◽  
Photoelectron Spectroscopy ◽  
Plasma Nitriding ◽  
Nitrided Layer ◽  
Multilayer Coating ◽  
Surface Texturing ◽  
X Ray ◽  
Dlc Coating ◽  
Hard Chrome

In cold rolling, a textured roll can be used to imprint a desired surface topography onto the sheet during rolling. This work proposes the use of diamond-like carbon (DLC) coatings to protect the surface topography of the rolls in replacement of the carcinogenic hard chrome. For that, hydrogenated amorphous carbon (a-C:H) was deposited on plasma nitrided tool steel, both for ground and textured specimens. Changes in surface topography due to DLC coating were assessed using a confocal microscope. Coating adhesion was evaluated using the method VDI 3198. The specimens were characterized using X-ray diffraction (XRD), microhardness test and scanning electron microscopy (SEM). The coating was characterized using Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS). The results showed a soft multilayer coating consisting of a plasma nitrided layer for load support, a Si-rich interlayer to improve adhesion and an a-C:H top layer. DLC deposition reduced the roughness of the textured specimens. The coating resulted in relatively stable friction and good durability, with small damage and negligible wear even under dry sliding.

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