INFLUENCE OF SURFACE PRE-HEATING ON THE NITRIDING DEPTH OF STEEL 25CrMoVA USED COMPLEX ION-PLASMA TREATMENT

In the method of nitriding elements, various methods of their thermal heating are used. The simplest heating method in ion-plasma nitriding is heating by bombarding the surface first with low-energy gas ions and then with metal ions with energies up to several kiloelectronvolt. Elements exposed to ion bombardment have a welldeveloped surface that is free from contaminants and facilitates the diffusion of nitrogen into the depth of the metal during nitriding. The paper studies the effect of various preliminary heating methods on the nitriding depth in the complex ion-plasma hardening technology of 25CrMoVA steel. A JSM 7000-1F scanning electron microscope equipped with an X-ray spectral energy dispersive microanalysis attachment was used to diagnose changes occurring on the surface of the samples and at depth; the hardness was measured using a Nanoindentor G200 device. The preliminary heating of the samples was carried out both with the use of bombardment with Ti or Mo ions, and without its direct effect on the heated surface. In the experiment, differences in the depth of hardening of the nitrided layer of steel are observed when it is heated in different ways. When bombarded with Mo ions, the greatest depths of hardening were obtained in comparison with other preliminary heating conditions. It is shown that these differences are associated with the features of the morphology of the steel surface formed as a result of sputtering processes. The formation of nitride compounds in its surface layer can serve as a barrier that slows down the penetration of nitrogen into the metal. It is shown that with complex treatment in the process of deposition of a nitride coating on the surface of nitrided steel, an additional increase in the depth of hardening of the nitrided layer occurs.

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Possibilities of Additive Technologies for the Manufacturing of Tooling from Corrosion-Resistant Steels in Order to Protect Parts Surfaces from Thermochemical Treatment

Metals ◽

10.3390/met11101551 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1551

Author(s):

Alexander Metel ◽

Tatiana Tarasova ◽

Evgenii Gutsaliuk ◽

Roman Khmyrov ◽

Sergei Egorov ◽

...

Keyword(s):

Mechanical Properties ◽

Plasma Nitriding ◽

Nitrided Layer ◽

Linear Thermal Expansion ◽

Thermochemical Treatment ◽

Spheroidal Graphite ◽

Corrosion Resistant ◽

Ion Plasma ◽

Composition And Structure ◽

Stage 1

The structure and physical–mechanical properties of products made from powders of corrosion-resistant steel 12X18H10T by the laser-beam powder bed fusion (LB-PBF) and subsequent ion-plasma nitriding in the work were investigated. Comparative studies of the physical mechanical properties of specimens made by the LB-PBF and conventional method from steel of the same grade were carried out. The density of the specimens and the coefficient of linear thermal expansion (CLTE) after the LB-PBF are almost the same as those of the conventionally manufactured specimens. Our analysis of the obtained dilatograms in the temperature range from 20 to 600 °C showed that the CLTE of steel after the LB-PBF is within acceptable limits (18.6 × 10−6 1/°C). Their hardness, tensile strength, yield strength and elongation are higher than those of a conventionally manufactured specimen. The phase composition and structure of specimens of steel 12X18H10T made by the LB-PBF after the process of ion-plasma nitriding were investigated. The obtained results show that the mode of ion-plasma nitriding used in this case (stage 1—570 °C for 36 h; stage 2—540 °C for 12 h) does not lead to deterioration of the characteristics of the selected steel. A technological process for the manufacture of modified tooling from 12X18H10T steel by the LB-PBF was developed. It protects the surfaces that are not subject to nitriding and makes it possible to obtain a uniform high-quality nitrided layer on the working surface of the part made from spheroidal graphite iron.

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Investigation of formation of hardened layer on titanium alloys by the method of ion-plasma nitriding

Proceedings of the National Academy of Sciences of Belarus Physical-Technical Series ◽

10.29235/1561-8358-2019-64-1-25-34 ◽

2019 ◽

Vol 64 (1) ◽

pp. 25-34

Author(s):

I. L. Pobol ◽

I. G. Oleshuk ◽

A. N. Drobov ◽

Sun Feng ◽

Wang Lin

Keyword(s):

Corrosion Resistance ◽

Friction Coefficient ◽

Titanium Alloys ◽

Plasma Nitriding ◽

Nitrided Layer ◽

Saturation Pressure ◽

Hardened Layer ◽

Technological Parameters ◽

Ion Plasma ◽

Increase Wear Resistance

Various methods are applied in the world practice to increase wear resistance, fatigue strength and corrosion resistance of aviation equipment, machinery and medicine parts made of titanium and its alloys. Ion-plasma nitriding provides the ultimate effect making it possible to obtain hardened layers with hardness of HV0.01 650–1000 with a thickness of 0.07–0.20 mm for 3–6 hours, depending on the grade of the titanium alloy.Technological factors effecting on the efficiency of ion-plasma nitriding of materials are the process temperature, duration of saturation, pressure, composition and flow rate of the working gas mixture. The effect of these technological parameters on the microstructure, microhardness and depth of hardened layers is investigated in the work. It is shown that hardness and depth of the nitrided layer can be controlled by changing the composition, volume and periodicity of the gaseous medium (nitrogen and argon) supply at the stages of heating and holding time of the samples from titanium and its alloys under ion-plasma nitriding. The tribological characteristics of titanium alloys as-received and the same ones subjected to ion-plasma nitriding under friction conditions without a lubricant were studied. For VT1-0 and VT6 alloys in the as-received state during the tests there is a monotonous decrease of the friction coefficient from 0.35–0.40 to 0.25, after nitriding the friction coefficient monotonically increases from 0.14 up to 0.30 when removing the hardened layer.Studies of corrosion resistance of titanium VT1-0, carried out in a 10 % solution of sulfuric acid, showed that after ion-plasma nitriding at a temperature of 830 °C for 6 hours, the corrosion resistance increases, as the positive polarization potential of the sample shows.

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Nitriding of yttria-stabilized zirconia in atmospheric pressure microwave plasma

Journal of Materials Research ◽

10.1557/jmr.2009.0245 ◽

2009 ◽

Vol 24 (6) ◽

pp. 2021-2028 ◽

Cited By ~ 4

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.

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

Coatings ◽

10.3390/coatings11020112 ◽

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.

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

Coatings ◽

10.3390/coatings11020201 ◽

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

Coatings ◽

10.3390/coatings11091122 ◽

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.

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Novel Electrodeposited Ni-Based Nanocomposite Precursors for Nitriding and Low Temperature Chromizing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.522-523.331 ◽

2006 ◽

Vol 522-523 ◽

pp. 331-338

Author(s):

X. Peng ◽

J. Zhao ◽

Hong Yan Zhang ◽

Fu Hui Wang

Keyword(s):

Low Temperature ◽

Oxidation Resistance ◽

Plasma Nitriding ◽

Nitrided Layer ◽

Pack Cementation ◽

Coarse Grained ◽

Crn Coating ◽

Cr Content ◽

Oxidation Resistant

Two types of Ni-base nanocomposites were prepared by co-deposition of Ni with nano-sized particles of Cr or CeO2, respectively. Both Ni-Cr and Ni-CeO2 nanocomposites were mainly composed of nanocrystalline Ni matrix, in which certain content of nanoparticles of Cr or CeO2 randomly dispersed. The Ni-Cr nanocomposite was used as a precursor for preparing a novel hard Ni/CrN coating by plasma nitriding at 560oC. The Ni-CeO2 nanocomposite was used as a precursor to develop a novel oxidation-resistant chromia-forming coating by low temperature chromizing using a conventional pack-cementation method. The microhardness of the nitrided layer on the Ni-Cr nanocomposite and the oxidation resistance of the chromizing coating on the Ni-CeO2 nanocomposite were both greatly increased, in comparison to the corresponding counterparts, which were obtained by plasma nitriding on a conventional coarse-grained Ni-Cr alloy with similar Cr content and by chromizing on a coarse-grained Ni metal, respectively. The relationships among the microstructures of the nanocomposite precursors and the nitrided/or chromized coatings, and their properties were investigated and discussed.

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Possibilities of Preparing Tools Working in Conditions of Abrasion Wear with the Modification of the Tool Surfaces by Nitridation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.635.89 ◽

2014 ◽

Vol 635 ◽

pp. 89-93

Author(s):

Martin Orečný ◽

Petra Lacková ◽

Marián Buršák

Keyword(s):

Wear Resistance ◽

Nitrided Layer ◽

High Hardness ◽

Chromium Steel ◽

Material Surface ◽

Diffusion Annealing ◽

Additional Increase ◽

Abrasion Wear ◽

Heat Treated

The proposed paper deals about the heat treatment of two types of chromium tool steels that are assigned to work in specific conditions of abrasion wear. The materials are heat treated to achieve high hardness for higher abrasion wear resistance. An additional increase of the materials abrasion wear resistance can be achieved by applying nitridation with diffusion annealing of the material surface. The paper deals about the influence of the material purity, his chemical composition on the process of diffusion, the quality of the nitrided layer of a vacuum smelted steel Bӧhler W400 VMR and a chromium steel X210Cr12.

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Evaluation of stress-strain behavior of surface treated steels by X-ray diffraction

Open Engineering ◽

10.2478/s13531-011-0051-4 ◽

2012 ◽

Vol 2 (1) ◽

Cited By ~ 1

Author(s):

Luis Coelho ◽

A. Batista ◽

J. Nobre ◽

M. Marques

Keyword(s):

Yield Strength ◽

Plasma Nitriding ◽

Nitrided Layer ◽

Experimental Methodology ◽

X Ray Diffraction ◽

Stress Strain ◽

X Ray ◽

Strain Behavior ◽

Four Point Bending ◽

Nitride Layers

AbstractX-ray diffraction assisted four-point bending method (XRDABM) enables to analyze the evolution of surface stress with the strain during bending of specimens. This experimental methodology was used to characterize the stress-strain behavior of two plasma nitriding steels, DIN 40 Cr Mn Mo 7 and DIN 32 Cr Mo V 13, with gradients of mechanical properties across the surface layers, allowing the characterization of the in-depth evolution of the local yield strength in the nitrided layer. The results show a significantly increase of the yield strength of the nitride layers and a good agreement between the in-depth evolution of the yield strength and the XRD peak breadth for the two nitrided steels.

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