Liquid Nitriding Research Articles

EFFECT OF COATING TYPE ON TRIBOLOGICAL RESPONSE OF H13 TOOL STEEL

Tribology is the study of friction, wear and lubrication. This work aims to study the effect of coatings on the wear behavior of H13 tool steel. Liquid nitriding, plasma nitriding, PVD TiN coating and DLC were utilized on H13 tool steel for increasing the tool life, quality of drilled holes and to reduce the cost of tool material. The wear behavior of H13 was evaluated using pin on disc wear test. Microstructural and scanning electron microscope analysis of wear surface of tool was carried out to identify the best coating and wear mechanism. This study reveals that PVD-TiN-coated H13 tool exhibited the best wear response and least coefficient of friction hence can be selected for friction drilling process.

Research of Alternative Options for Strengthening Surface Treatment of Cast Iron Products

The article considers issues of increasing wear resistance of cast iron products by methods of thermochemical treatment of their surface layer. Methods are proposed to solve the problem of wear from cast iron of grade EN-JS1060 due to development of technological processes of strengthening treatment. Alternative versions of strengthening technologies are represented by nitrocarburizing, liquid nitriding and carbonitration. Results of examination of control samples at increasing loads after 200 N before catastrophic wear are given. Comparative analysis of these results showed that samples after carbonitration and liquid nitriding had the greatest bearing capacity (1000 N). Carbonitration is selected as a most preferred option of the surface hardening treatment. Non-poisonous cyanoacid salts are used to realize it.

Dry Sliding Wear Behavior of Austenitic Stainless Steel Material by Gas Nitriding Process

In industries, components must operate under extreme conditions such as high load, speed, temperature and chemical environment. Materials are selected according to commercial availability, cost and their properties such as strength, hardness, etc. AISI 904L is a high-alloy stainless steel with low carbon content, poor surface hardness and wear characteristics. Many engineering failures are caused by fatigue, corrosion, and poor wear resistance, begins at the surface level. This causes cracks in the surface, reducing the material’s life. The surfaces of the materials were subjected to severe thermal, chemical, and shock loads. The selected AISI 904L materials for this work were subjected to gas nitriding process and processed with 3 different time parameters such as 12 hours, 18 hours and 24 hours respectively and named as GN1, GN2 and GN3. The treatments were done at a constant temperature of 650°C. Gas nitriding, in comparison to other nitriding processes such as plasma and liquid nitriding, provides good dimensional stability, reduced deformation, and uniform case depth regardless of the size and shape of the specimen. To analyze the wear properties, a pin on a disc machine is used. Finally, metallographic studies were performed by scanning electron microscopy.

Influence of liquid nitriding on the properties of the electric steel 10

Liquid nitriding (carbonitriding) effect on hardness, wear resistance and magnetic properties of electric steel grade 10 is reviewed here, as well as on the electric contact resistance. It was found that hot-rolled steel 10 loses its hardness as a result of annealing. Surface carbonitriding of specimens generates an improved layer of higher hardness, high wear resistance and increased electrical resistance. The specimens carbonitrided have contact electric resistance higher than that of hot-rolled specimens after descaling. The magnetic permeability of ‘grade 10’ steel does not practically change after annealing and carbonitriding, while the magnetic permeability corresponds to the magnetic field strength in a very typical way with typical parameters for carbon steels. Traditional methods of processing electrical steels, carried out in order to achieve such a complex effect, combine heterogeneous processes, such as electroplating, vacuum, plasma, high - temperature annealing, coating-are very expensive and difficult to implement. Carbonitration is more accessible for practical use and has a significantly lower cost. The results obtained can be used in the design of magnetic circuits for various electric devices.

Optimization of coated friction drilling tool for a FML composite

ABSTRACT In the present research, an attempt was made to determine the suitable coated tool for drilling AA5052 nano hybrid sandwich sheet using Response Surface Methodology (RSM) and Taguchi method. The work aims at minimizing thrust force and torque on a friction drilling tool for drilling holes. Plasma Nitriding, Liquid Nitriding, and PVD Titanium Nitride (TiN) coating are applied on H13 steel tool material. Results indicate that for achieving minimum torque and thrust force, feed of 50 mm/rev and spindle speed of 4000 rpm to be used during drilling. Whereas, to reduce the drilling time, feed has to be increased up to 200 mm/rev. The maximum bushing height is 5.6 mm for Liquid Nitrided tool at 2500 rpm, 50 mm/rev, and 5.4 mm for PVD TiN-coated tool at 3000 rpm, 200 mm/rev, whereas 4.71 mm is the minimum bushing height for Plasma Nitrided tool at 3500 rpm, 150 mm/rev. The result obtained from RSM was compared with Minitab response optimizer and Harmonic Search Algorithm. PVD TiN coated tool exhibited the best performance in terms of low thrust force value of 84.70 N at 4000 rpm, 50 mm/rev and low torque value of 1.5395 N-m at 2500 rpm, 50 mm/rev.

Influence of Nd:YAG Laser Energy on Mechanical properties of Nitriding Steel

Desired mechanical properties like microstructure, micro hardness and wear resistance are the key parameters for which low carbon steel (AISI 1006) are widely selected. Surface heat treatment applied to improve these properties; traditionally surface heat treatments like induction hardening, in recent time’s laser surface hardening. In this work, thermochemical treatment (liquid nitriding) by using mixture from 61% NaCN, 15% K2CO3 and 24% KCL and followed by Nd:YAG laser surface treatment was done . The laser parameter were energy (0.89, 2, 4 and 9) J, spot diameter (0.790 ,0.33, 0.283 and 0.224) mm, pulses duration (1, 2.33, 4.47 and 9.87) ms with fix wavelength 1604nm. Laser surface treatment cycle was melting the layer surface, holding and rapid cooling in air medium. Optical microscopy (OM) and scanning electron microscope (SEM) has been used to study the microstructures and cross-sectional of molted and heat affected zones respectively. The wear test was done to measure the wear rate by using pin -on-disk principles were satisfied. The result shown that increasing in laser energy effects to increase in the area of melted and heat affected zones of nitriding steel. Also increasing in laser energy led to increase micro hardness about 61%, while wear rate decrease about 40 % and increased depth of molted zone.

Enhancement of wear and erosion-corrosion resistance of Inconel 718 alloy by liquid nitriding

Inconel 718 alloy is often used for the oil and gas industry, which usually failed due to the erosion-corrosion of multi-phase flow. In this study, we expect to enhance the wear and erosion-corrosion resistance of Inconel 718 alloy by liquid nitriding and a high-hardness nitrided layer with the thickness of about 9.5 μm on the surface of Inconel 718 alloy was formed by liquid nitriding. Wear and erosion-corrosion tests were performed on untreated and nitrided Inconel 718 alloys. Results show that abrasive wear and adhesive wear occurred in both nitrided and untreated samples at different temperatures (25 °C, 100 °C and 200 °C). The width and depth of the wear track and the wear rate of the nitrided samples are all smaller than that of the untreated samples. Liquid nitriding significantly improves the wear resistance of Inconel 718 alloy because of the high-hardness nitrided layer. The nitrided Inconel 718 alloy exhibited an improvement of almost 80.3% in the erosion-corrosion resistance compared to their untreated counterparts. The weight loss rate of the erosion-only shows an obvious reduction after liquid nitriding. The surface nitrided layer with high hardness effectively protects the substrate, and prevents the material from the erosion-corrosion of multi-phase flow consisting of the SiO2 particles and the acidic solution, so that the total weight loss of nitrided Inconel 718 alloy decreased evidently.

Optimization of plasma nitrided, liquid nitrided & PVD TiN coated H13-D2 friction drilling tool on AZ31B magnesium alloy

This study investigates the effects of input parameters and coating techniques for realizing smooth surface finish on AZ31B magnesium alloy. Response surface methodology was used for predicting the best input parameters. Three kinds of coating parameters were adopted on a H13-D2 friction drilling tool. Lightweight magnesium alloy (AZ31B) of less than 4 mm commonly used in automotive and aeronautical sectors was used as working material in this research. Plasma nitriding, Liquid nitriding and PVD- Titanium coating techniques were used for increasing the tool life. The main focus of this research was to find an optimized coated tool. Surface roughness and time consumption during friction drilling technique was focused in this research. Using ANOVA, it was established that PVD Titanium Nitrided H13-D2 tool is best suited for machining AZ31B alloy realizing a surface roughness of 0.43 µm at 4000 rpm & 50 mm/rev.

Formation of Multiple Phase Microstructure and Wear Investigation on Treated AISI 904L SS by Low Temperature Ion Nitriding Process

In industries, components have to operate under extreme prerequisites such as high load, speed, temperature and at a chemical environment. The materials are selected by commercial availability, cost and by considering by their properties like strength, hardness etc. AISI 904L is a high alloy stainless steel with low carbon content material having poor hardness on the surface and negative wear properties. Many of the engineering failures are due to fatigue, corrosion and poor wear resistance which are initiated in its surface. This causes cracks in the surface which reduces the life of the material. Also the surfaces of the materials are caused by severe thermal, chemical and shock loads. Chosen for this work, AISI 904L materials were subjected to plasma or ion - nitriding process and were treated to 3 different timing parameters like 24 hrs, 48 hrs and 72 hrs respectively, maintaining constant temperature of 650oC. Among the availability of other nitriding process like gas and liquid nitriding, plasma nitriding gives good dimensional stability, uniform treatment, less distortion, uniform case depth irrespective towards size and shape of the specimen. For analyzing the wear properties, a pin on disc machine is utilized making the pin to get weared on disc against a load of 100N at a speed of 1000 rpm. Finally the metallographic studies were done by Scanning Electron Microscopic analysis.

Structure and Topography Modifications of Treated AISI 316LN Stainless Steel Surfaces after Friction in Dry Sliding Contact by Case Hardening Process

Austenitic stainless is having corrosion resistance property, but certain mechanical applications require improved resistance to wear, inferior cavitation, susceptibility to sensitization. These steels have numerous favourable circumstances for great cryogenic - properties, anti-corrosion, and bio-compatibility. So these steels have a broad application in low temperature innovation, saltwater applications, nourishment industry, bio-medicine, petro-chemical handling, and so forth when alloyed with nitrogen, austenitic treated steels has a progressively steady austenite structure, better mechanical properties and better wear opposition, which has animated extraordinary enthusiasm for this exploration work. Many surface hardening techniques are available, the best surface modification technique is chosen for improved service performance. Surface engineering is a technique to alter the surface of a material by mechanical or microchemical method without affecting the material properties. The alterations are done on the surfaces subjected to the liquid nitriding process to produce a hardened surface. Chosen for this research workbased on their wide application, the wear behaviour of AISI 316LN stainless steels was investigated. Of the various surface hardening techniques available, nitriding is chosen, so that these nitrogen gets penetrated into the material, in which hard iron chromium nitrides are formed at the surface level. AISI 316LN specimens were subjected to salt bath nitriding process. The specimens were nitrided to 60 minutes, 120 minutes and 180 minutes respectively. The specimens were undergone with wear tests by standardized tribiological wear machine and finally the metallographic studies were made.

Liquid Nitriding of Stainless Steel 316L to improve fatigue properties for Orthopedic Screws

Liquid nitrate is an important method used to improve mechanical properties. One of these properties is resistance to fatigue. The aim of this study was to improve the fatigue resistance of the stainless steel 316L. The rotational bending method was used with constant and variable stresses at different times of (1, 3, 5) hours and at (530, 630) C0. These tests were performed before and after nitration.
 The results showed that the depth of the nitride layer was (0.21, 0.33, 0.45) mm, increasing with time nitriding when the temperature was 530 C0. While the depth of this layer at a temperature of 630 C0 (0.26, 0.39,0.5) mm with increasing time. As a result of these processes, a layer of solid chromium nitrides and other phases of iron nitride were formed on the outer surface. These layers helped to inhibit the growth of the cracks and their progress in addition to the generation of pressure stresses on the surface leading to obstructing the progress of the cracks.
 This study showed that the fatigue resistance was directly proportional to the increase in nitrate time due to the increased depth of the hardened layer, but this resistance decreased when the temperature was 630 C0 due to the formation of brittle phase with low resistance.

The Effect of Liquid Nitriding on the Corrosion Resistance of AISI 304 Austenitic Stainless Steel in H2S Environments

AISI 304 austenitic stainless steel was low-temperature liquid nitrided in a molten salt bath at 703 K for 8 hours, which produced a 3-layered structure consisting of a top oxide layer, an intermediate nitrogen-rich layer and a bottom carbon-rich layer. The effect of nitriding on its corrosion resistance was investigated in a H2S environment. The corrosion rate of the untreated sample is about 3.3 times that of the nitrided sample after H2S corrosion. Corrosion pits can be clearly observed on the surface of the untreated sample, while the nitrided sample surface remained relatively intact. Both the oxide layer and the nitrogen-rich layer can help reduce the hydrogen permeation, which is beneficial for combating hydrogen embrittlement. The corrosion products mainly consisted of oxides, hydroxides, and sulfates. The nitrided layers can serve as a barrier to corrosion, thus preventing the corrosion of the substrate material. Active nitrogen in the nitrided layer reacts with H ions to form NH4+, which effectively prevents further acidification of the local area and inhibits the occurrence of pitting corrosion and the dissolution rate of the metal in the etching hole, thus improving the local corrosion resistance of the stainless steel.

Corrosion conduct of Austenitic stainless steel 316L subjected to surface treatment

The influence of low temperature liquid nitriding as a surface heat treatment analogy with laser peening treatment at the various of throbs on pitting corrosion of the “AISI 316L Austenitic stainless steel” is investigated in this paper. According to typical ASTM (G71-31) a number of corrosion examination samples are equipped with the measurements of (15 * 15 * 3) mm which distributed into the many groups. Three sets were exposed to liquid nit riding process at temperatures of (500, 400, 300) Co for one hour. The specimens (without coating) were exposed to a number of the throbs (1,2,3) by laser peening. Microstructure variations, compression residual stress, hardness, were inspected in this work. The corrosion and its variables (potential cell, current density) were also evaluated using the potential stat examination and applying the Tafel method using saltwater solution (3.5% NaCl). Tafle equation was used to compute the corrosion degree. The results revealed that the liquid nitriding participated to raise the corrosion rate at (500) Co, compared to the original metal because of chromium nitride and also leaser peening participated to the increase in the corrosion rate due to plastic deformation which led to the heterogeneity in the microstructure but liquid nitriding at temperature (400) °C gave the best result where it was closer to the parent metal’s, also laser peening at one throb showed the lower corrosion rate.

Distortion control in 20MnCr5 bevel gears after liquid nitriding process to maintain precision dimensions

Robotic and automotive gears are generally very high precision components with limitations in tolerances. Bevel gears are more widely used and dimensionally very close tolerance components that need stability without any backlash or distortion for smooth and trouble free functions. Nitriding is carried out to enhance wear resistance of the surface. The aim of this paper is to reduce the distortion in liquid nitriding process, though plasma nitriding is preferred for high precision components. Various trials were conducted to optimize the process parameters, considering pre dimensional setting for nominal nitriding layer growth. Surface cleaning, suitable fixtures and stress relieving operations were also done to optimize the process. Micro structural analysis and Vickers hardness testing were carried out for analyzing the phase changes, variation in surface hardness and case depth. CNC gear testing machine was used for determining the distortion level. The presence of white layer was found for about 10-15μm in the case depth of 250± 3.5μm showing an average surface hardness of 670 HV. Hence the economical liquid nitriding process was successfully used for producing high hardness and wear resistant coating over 20MnCr5 material with less distortion and reduced secondary grinding process for dimensional control.

Erosion–corrosion resistance properties of 316L austenitic stainless steels after low-temperature liquid nitriding

The low-temperature liquid nitriding of stainless steels can result in the formation of a surface zone of so-called expanded austenite (S-phase) by the dissolution of large amounts of nitrogen in the solid solution and formation of a precipitate-free layer supersaturated with high hardness. Erosion–corrosion measurements were performed on low-temperature nitrided and non-nitrided 316L stainless steels. The total erosion–corrosion, erosion-only, and corrosion-only wastages were measured directly. As expected, it was shown that low-temperature nitriding dramatically reduces the degree of erosion–corrosion in stainless steels, caused by the impingement of particles in a corrosive medium. The nitrided 316L stainless steels exhibited an improvement of almost 84% in the erosion–corrosion resistance compared to their non-nitrided counterparts. The erosion-only rates and synergistic levels showed a general decline after low-temperature nitriding. Low-temperature liquid nitriding can not only reduce the weight loss due to erosion but also significantly reduce the weight loss rate of interactions, so that the total loss of material decreased evidently. Therefore, 316L stainless steels displayed excellent erosion–corrosion behaviors as a consequence of their highly favorable corrosion resistances and superior wear properties.

Effect of liquid nitriding at 400–670 °C on microstructure and properties of C110 steel

Liquid nitriding of C110 steel was conducted in a wide range of temperatures (400–670 °C) using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly depended on the processing condition. When C110 steel was subjected to liquid nitriding at 430 °C, the nitrided layer was almost composed of a thin e-Fe2–3N layer. When C110 steel was subjected to liquid nitriding at 640 °C, the phase composition of the nitrided layer was greatly changed. The nitrided layer depth increased significantly with increasing the treating temperature. The liquid nitriding effectively improved the surface hardness. After liquid nitriding, the absorption energy of the treated sample decreased and the tensile strength increased by Charpy V-notch (CVN) test. But the elongation of treated sample decreased. The reason is that the nitrided layer of sample is hardened and there is brittlement by diffusion of nitrogen atom. Despite of treatment temperature, the liquid nitriding can improve the corrosion. After being nitrided at 430 °C, the nitrided layer of the C110 steel was mainly composed by e-Fe2–3N, which has excellent corrosion resistance and high microhardness, the nitrided sample has the best corrosion resistance. After nitriding temperature over 580 °C, especially at 680 °C, the sample’s surface was covered by the thick oxide layer, which has very low hardness and corrosion resistance. So, the corrosion resistance of samples is severely compromised.

Liquid phase surface nitriding of aluminium using TIG process

Liquid phase surface nitriding of AA5052 aluminium was performed using the heat of a TIG (tungsten inert gas) torch in a gas shielding which was a mixture of argon and nitrogen. The feasibility of obtaining nitride compounds at various TIG processing parameters and nitrogen contents in the shielding gas were studied. The presence of AlN phase was proved by X-ray diffraction analysis. Scanning electron microscopy with EDS analyser was carried out to study the morphology and chemical composition of the nitride phase. The microhardness test was also performed on cross sections of treated layers. This measurement demonstrated that the surface hardness of the untreated aluminium was increased from 52 HV for the untreated aluminium alloy to as high as 1411 HV for the nitrided sample. It was also noticed that liquid phase surface nitriding reduced the wear rate to less than quarter of that of the untreated substrate.

Phase Transformations During the Low-Temperature Nitriding of AISI 2205 Duplex Stainless Steel

Liquid nitriding of type AISI 2205 duplex stainless steel was conducted at 723 K (450 °C), using one type of novel low-temperature liquid chemical thermo-treatment. The transformation of the nitrided surface microstructure was systematically studied. Experimental results revealed that a nitrided layer formed on the sample surface with the thickness ranging from 3 to 28 μm, depending on nitriding time. After the 2205 duplex stainless steel was subjected to liquid nitriding 723 K (450 °C) for less than 8 hours, the pre-existing ferrite region on the surface transformed into the expanded austenite (S phase) by the infusion of nitrogen atoms, most of which stay in the interstitial sites. Generally, the dominant phase of the nitrided layer was the expanded austenite. When the nitriding time prolonged up to 16 hours, some pre-existing ferrite in expanded austenite was decomposed and e-nitride precipitated subsequently. When the treatment time went up to 40 hours, large amount of e-nitride and CrN precipitates were observed in the pre-existing ferritic region in the expanded austenite. Furthermore, many nitrides precipitated from the pre-austenite region. Acicular nitride was identified by transmission electron microscopy. The thickness of the nitrided layer increased with increasing nitriding time. The growth of the nitrided layer is mainly due to nitrogen diffusion in accordance with the expected parabolic rate law. Liquid nitriding effectively increased the surface hardness of 2205 duplex stainless steel by a factor of 3.

Advance Complex Liquid Nitriding of Stainless Steel AISI 321 Surface at 430 °C

Liquid nitriding of type 321 austenite stainless steel was conducted at low temperature at 430 °C, using a type of a complex chemical heat-treatment; and the properties of the nitrided surface were evaluated. Experimental results revealed that a modified layer was formed on the surface with the thickness ranging from 2 to 30 μm varying with changing treatment time. When the stainless steel subjected to the advanced liquid nitriding less than 8 h at 430 °C, the main phase of the nitrided coating layer was the S phase generally. When the treatment time prolonged up to 16 h, S phase formed and partially transformed to CrN subsequently; and then the fine secondary CrN phase precipitated. All treatments performed in the current study can effectively improve the surface hardness. The nitrided layer thickness changed intensively with the increasing nitrided time. The growth of the nitride layer took place mainly by nitrogen diffusion according to the expected parabolic rate law. The highest hardness value obtained in this experiment was about 1400 Hv0.25. Low-temperature nitriding can improve the corrosion resistance of the 321 stainless steel against diluted vitriolic acid. The immerse test results revealed that the sample nitrided for 16 h had the best corrosion resistance than the others. SEM examinations indicated that after nitriding, the corrosion mechanisms of the steel had changed from serious general corrosion of untreated sample to selectivity corrosion of nitrided samples in the diluted vitriolic acid.

Fe-Si合金及びFe-C-Si合金の塩浴窒化に及ぼすSiの影響とFe,Siの窒化物について

Fe-Si合金及びFe-C-Si合金の塩浴窒化に及ぼすSiの影響とFe,Siの窒化物について