Nitrided Steel Research Articles

The compatibility of nitrided W18Cr4V steel in a sodium environment

The guideway friction pairs are the key components of the loading elevator and unloading elevator in the refueling system for sodium cooled fast reactor. With the excellent hardness and wear resistance in air, nitrided W18Cr4V steel is a candidate material for the guideway friction pairs. In order to evaluate the applicability in the high-temperature sodium, it is important to conduct the compatibility tests of nitrided W18Cr4V steel for different exposure time. The results show that the nitrogen content of nitrided W18Cr4V steel decreased obviously after 1000 h, 2000 h and 3000 h sodium compatibility tests at 540 °C and the nitrided strengthening effect of W18Cr4V steel gradually decreased with the test duration increasing.

Optimization and control of gaseous nitriding of a 33CrMoV12-9 steel

Abstract This work propose a new experimental methodology to optimize the gaseous nitriding process of 33CrMoV12-9 steel grade, widely used in the mechanical industry for the fabrication of gears, pinions, and bearings. Several nitriding experiments were conducted at a temperature of 520 °C in the interval between 4 and 55 h using both constant and variable nitriding potential K N . The obtained results allowed us to determine the optimal conditions and to propose a sequenced cycle consisting of three steps. Multiple characterizations using X-ray diffraction (XRD), optical microscopy (OM), Vickers microhardness testing (HV), and electron probe microanalysis (EPMA) indicate a surface hardness of 810 HV0.5, nitrogen diffusion depth of approximately 0.7 mm. finally, a metallurgical structure devoid of complex networks of nitrides and carbonitrides. The validation results confirmed the effectiveness of the proposed methodology, thereby paving the way for improving the nitriding process in the mechanical industry. This work represents a significant contribution to the optimization of thermochemical treatments for materials used in demanding environments.

Hybrid methodology development for lubrication regimes identification based on measurements, simulation, and data clustering

The lubrication regimes of a laboratory scale journal bearing were analysed with wide band acoustic emission (AE) measurements. The analysis was supported by data-based clustering of AE data. Digital twin of the journal bearing was generated with Simpack multi-body simulation software to study opportunities for developing a hybrid methodology for more complex systems monitoring. The AE and data-based clustering approach can be effectively used to reveal fundamental lubrication modes, i.e., hydrodynamic (HL), mixed (ML) and boundary (BL) lubrication as a function of Hersey number, which can be evaluated in situ by utilizing digital twin. Besides AE the other parameters monitored were friction torque, bearing temperature, loading, sliding velocity and oil pressure. The materials used in the experiments were case-hardened 18CrNiMo7–6 steel and nitrided 42CrMo7 steel. The tests were lubricated with synthetic extreme-pressure gear oil (SGN 320) and the bearing temperature was kept constant during the tests. The bearing loading and sliding velocity during tests were varied in the wide range resulting in different lubrication situations. The acoustic emission signals power and frequency content was analysed, and essential features were extracted for data clustering. For lubrication regime change identification the parameters such as signal RMS and coefficient of variation (CV) proved to be important, while signal kurtosis showed to be the most sensitive in discovering anomalies. The high sensitivity requires data filtering to remove erroneous peaks and to reveal real trends more clearly. It is also interesting to notice the changes in AE frequency during changing to different lubrication regime. In literature different clustering and classification methods has been proposed and applied for journal bearing status identification. Here the selected unsupervised clustering method was the mean-shift clustering due to fact, that the lubrication regimes in the Stribeck curve form an inseparable continuum. The algorithm does not require specifying the number of clusters in advance, i.e., the clusters are determined by the algorithm with respect to the data. The results were compared to simulations with digital twin. i.e., by comparing simulated digital twin film thickness and measured AE kurtosis relative to measured Hersey number. It was concluded that digital twins can be utilized as virtual sensor for in situ detecting of lubrication regimes, if it is possible to calibrate the simulation with sensitive measurements, e.g., AE. It is obvious that simulations alone cannot predict suddenly appearing anomalies, such as impurities or surface fatigue failures.

A Study on the Aging Behavior of Nitrided W18Cr4V Steel in High-Temperature Sodium

The loading and unloading elevators are the primary equipment in the refueling system, used for transferring fuel assemblies in the sodium-cooled fast reactors. The guideway friction pairs are the critical components of these elevators in the refueling system. With the excellent hardness and wear resistance in air, nitrided W18Cr4V steel is a promising material for the guideway friction pairs. In order to assess the feasibility of using nitrided W18Cr4V steel, it is essential to understand the aging behavior of nitrided W18Cr4V steel in high-temperature sodium. Aging tests were conducted on nitrided W18Cr4V steel in sodium and in argon environments at various temperatures for different exposure times. The results showed that the nitrogen atoms in the nitrided layer exhibited bidirectional diffusion behavior in the sodium or argon environment at 540 °C. Compared to the argon environment, cracks formed within the nitrided layer and the diffusion of nitrogen into the sodium was accelerated in the nitrided layer. As a significant number of nitrogen atoms had diffused into the sodium, there was little difference in the hardness between nitrided W18Cr4V steel and non-nitrided W18Cr4V steel after long-term exposure to 540 °C sodium.

Investigation on the optimal ultra-precision machining of nitriding mold steel by in-situ laser assisted diamond cutting

S136 (STAVAX ESR) mold steel is an advanced material for the optical mold industry. The precisely machined surface quality is essential for guaranteeing the excellent performance of molds. Diamond cutting is a high-efficiency machining technique in optical mold manufacturing. However, the chemical wear of diamond tool is a huge challenge in precisely machining steel mold due to the reaction between atoms C and Fe. In this study, the hybrid machining technique which combined the in-situ laser assisted diamond cutting (LADC) and plasma nitriding was used to machine S136 mold steel. Furthermore, the impact of the various machining conditions on the machined workpiece surface roughness Sa was comprehensively investigated by the Taguchi method (TM) and Response surface methodology (RSM). The experimental results of material characterization indicated that a 90 μm nitride layer was generated on the workpiece surface by plasma nitriding. Analysis of variance (ANOVA) results demonstrated that the feed rate and laser power had an important impact on the machined surface roughness Sa. According to the RSM, a precise mathematical model was developed which is explored by experimental investigations. The results showed that the optimal machining parameter combination by RSM generated the better surface quality of 6.393 nm in in-situ LADC of nitriding steel. This study provides a reference for mold steel ultra-precision machining technique and parameter optimization method for surface integrity.

Influence of Quenching and Tempering on the Tribological and Corrosion Behavior of Plasma‐Nitrided Society of Automotive Engineers 52100

Society of automotive engineers (SAE) 52100 (100Cr6) steel, used in manufacturing bearings and shafts, deserves attention due to wear and corrosion problems that cause machine losses in the industry. To solve these problems, heat treatments such as quenching and tempering are adopted to reduce wear mechanisms. However, in this work, the effect of these previous heat treatments on the final properties of plasma nitrided steel at three different temperatures (400, 450, and 500 °C) is evaluated. Surface hardness, tribological behavior, and corrosion resistance are evaluated. In the results of Vickers hardness, wear, and electrochemical analysis, it is shown that performing plasma nitriding at 400 and 450 °C on previously heat‐treated SAE 52100 steel provides better mechanical resistance and chemical integrity in a corrosive environment, making the studied steel more comprehensive for important industrial applications.

АНАЛИЗ ВЛИЯНИЯ ПРЕДВАРИТЕЛЬНОЙ И ЦИКЛИЧЕСКОЙ ПЛАСТИЧЕСКОЙ ДЕФОРМАЦИИ НА ХИМИКО-ТЕРМИЧЕСКУЮ ОБРАБОТКУ КОНСТРУКЦИОННЫХ СТАЛЕЙ

The subject of the study was thermodiffusion nitrided and silicified layers on steels obtained after plastic deformation. The influence of preliminary plastic deformation on the low-temperature nitriding process and cyclic plastic deformation on the high-temperature silicification process is studied. The results obtained are of interest for accelerating the production processes of chemical-thermal treatment of steels. It is established that preliminary surface plastic deformation contributes to the intensification of the process of ion-plasma nitriding of structural steel. The presence of high-temperature cyclic plastic deformation ensures the intensification of diffusion processes during the resorption of the diffusion silicified layer on structural steel.

Прогнозирование и оценка триботехнической эффективности азотированного слоя деталей машин

Following the laws of tribology and tribotechnics, also the results of experimental studies of reality of structure and properties change in the zone of contact tribodeformation of structural steels and alloys of different structural classes subjected to nitriding, an approach to forecasting and comprehensive assessment of the tribotechnical efficiency of nitriding of structural materials and products made of them has been developed. Analysis of the patterns of changes in the structure of the diffusion zone of nitriding steels: abnormal, martensitic and austenic, and relative wear resistance tests, taking into account their composition and technological parameters of the treatment process, showed that maximum wear resistance was provided by a nitration coating containing hardening dispersed particles of incoherent nitrides, ensuring a lower liability to brittle behavior of the nitration case due to low level of matrix level microdeformation. At the same time, preliminary types of treatment (thermal treating and deformation processing) of nitriding steels contribute to structural and phase state of the surface layer, which has added tribological performance. For nitrided ferroalloys with different matrix lattices, the most significant characteristics of the structural state and properties of the surface layers affecting the level of surface fracture under friction have been found empirically: the particle size of nitrides of alloying elements, the distance between them, the density of their distribution, the matrix lattice microdeformation, the values of X-ray lines intrinsic broadening for structural components of the material in the friction deformation zone, the hardness of the nitration case and its changes under friction. These experimental results are taken as a principle of the proposed method for forecasting and assessment of metal tribotechnical efficiency. This principle of method is based on a tribological criterion containing micro- and macroscopic characteristics of the material in the zone of contact deformation under friction, the choice of fabricating methods for the product takes place to ensure an acceptable level of wear intensity. Then, by measurement, using surface large deformation method, the ability of the nitration case formed as a result of treatment according to the selected treatment schedule to perceive surface nondestructive plastic deformation is evaluated. It affords a basis for the selected nitriding treatment schedule. The completion of the assessment is the determination of the values of the maximum operability of the nitriding material under conditions of friction and wear (alarm pressure when a tribocouple operates steadily; critical pressure when it is inoperable, but its operation is possible with short-term overloads; the average total wear intensity of the couple combined). The totality of the identified parameters allows recommending the material, its working and predicting operating modes and durability of tribounit.

Tribocorrosion assessment of low-temperature plasma nitrided super duplex stainless steel

The tribocorrosion of low-temperature plasma nitrided UNS S32750 super duplex stainless steel was investigated according to procedures for passivating materials. Nitrided and non-treated samples were compared through two reciprocating sliding tests in NaCl solution: the continuous test, without significant passive layer growth, and the intermittent one, with repassivation. Open circuit potential and linear polarization resistance (LPR) characterized the electrochemical response. LPR was successfully introduced to evaluate the polarization resistance evolution during the continuous test. Corrosion and mechanical wear components were quantified. The mechanical wear dominated, and nitrided samples showed lower wear volume loss. After the intermittent test, their values were further reduced. Such improvement was explained by the higher load bearing capacity and repassivation ability of the nitrided surfaces.

A study of cavitation erosion resistance of an ion nitrided titanium alloy by means of the vibration and rotating disk methods

In this work, a comparative analysis of the cavitation erosion resistance of the Ti–6.7Al–2.5Mo–1.8Cr–0.5Fe–0.25Si alloy (known as brand VT3-1) before and after low-temperature ion nitriding is carried out. Two test methods were applied, using vibrative (ASTM G-32) and rotating disk rigs, respectively. The kinetic dependences of the erosive destruction of samples of titanium alloy VT3-1 in the initial state, after ion nitriding and stainless steel AISI 321 were obtained. A study of the microstructure, hardness and surface morphology was carried out. The samples were examined using optical and scanning electron microscopy. The relationship between mass loss and cavitation erosion duration was experimentally determined and analyzed. The erosion rate on a rotating disk stand is much higher than during vibration tests. A large cavitation load gradient provides additional opportunities for analyzing the durability of materials and coatings using this method.

Methods for increasing the cavitation and solid particle erosion resistance of 20GL and 30L steels based on their surface modification

The article presents the results of studies of cavitation and solid particle erosion resistance of samples of 20GL and 30L steels with various surface modification options based on nitriding and boriding processes. Tests for cavitation resistance were carried out according to the ASTM G134-17, and for solid particle erosion resistance - according to the ASTM G76-13. It was revealed that to increase wear resistance, the depth of modification of the considered steels should be at least 80 microns. Based on the totality of cavitation and solid particle erosion studies carried out, the best option for surface modification for 20GL steel is boriding, and for 30L steel nitriding.

Tribological and corrosive degradation of differently surface engineered 17-4 PH steel

In the present work, a high-velocity oxy-fuel (HVOF) thermal spray process was used to deposit ceramic coatings containing alumina (Al2O3)− 0.8 wt% ceria (CeO2)− 0.2 wt% reduced graphene oxide (rGO) on 17–4 PH steel. The results were compared with the nitrided 17–4 PH (N17–4 PH) steel. The mechanical characteristics of the bare substrate, nitrided substrate, and coating were evaluated regarding micro (Vickers) hardness, scratch hardness, nanoindentation, and high-temperature nanoindentation (300 °C). The tribological behavior of all the specimens mentioned earlier was studied in a universal mechanical tester in a ball on flat reciprocating wear test mode for different loads. Electrochemical responses regarding corrosion properties in 3.5 wt% aqueous salt solution were recorded and analyzed. The results showed that the ceramic coating performed better than the other two specimens regarding mechanical, tribological, and electrochemical properties. For example, the coating was nearly ten and six times more wear resistant than 17–4 PH steel and N17–4 PH steel, respectively, at 50 N load. The performance enhancement in the coating was ascribed to the coating hardness, dense microstructure, and introduction of rGO in the coatings, which participate in the tribological process. Further detailed analysis of the bare steel, ceramic coating, and the nitrided steel properties reveals that the nitriding process can be replaced with the proposed ceramic coating through the HVOF technique for tribological, corrosive, and extreme environmental applications for 17–4 PH steel.

Effects of wall temperature and water vapor on the nitriding of stainless steel induced by ammonia flames

Ammonia is considered a promising alternative fuel for reducing CO2 emissions. However, the nitriding effect induced by ammonia flames poses a significant challenge that hinders its practical application in various industries. In the present study, to investigate the effects of temperature on the nitriding of stainless steel induced by ammonia flames, experiments were conducted by exposing SUS310S test plates to ammonia flames at different wall temperatures ranging from 550 °C to 850 °C. The distributions of chemical species in ammonia flames were obtained experimentally by means of the laser-induced fluorescence (LIF) technique and chemiluminescence measurement. Numerical simulations were also performed to estimate the ammonia flame structures with the consideration of surface reaction on the wall. In addition, the distributions of surface hardness and nitrogen atom concentration in the wall material were quantified by employing a nano-indenter and wavelength dispersive spectroscopy method (WDS), respectively. The LIF data for NH and NH3 concentration are in good agreement with the numerical results, highlighting the necessity of considering the surface reaction to accurately estimate the ammonia flame structure near the wall. It is also observed that both the surface hardness and the diffusion depth of nitrogen atoms into the wall decrease with increasing wall temperature, indicating a weakened nitriding effect at high wall temperatures. Notably, the NH3 concentration at the wall surface was identified as the most dominant parameter for the nitriding effect, while NH2 radicals also partially contribute to the nitriding. It is also found that the water vapor also hinders the nitriding.

Thermal and thermochemical treatments against fretting failure applied to power transmissions

Some power transmission components are subject to the fretting corrosion failure mode, which results in rapid wear of mating surfaces or premature fatigue crack initiation. Fretting corrosion is generated by micro-movements of surfaces in contact. In mechanical transmissions, it is found in particular on shrink-fit connections (bearing rings, for example) and on key and spline connections when they are misaligned or not with the well design fit.The sectoral board for mechanical transmissions and rolling bearings and CETIM is investigating the potential of technical solutions (materials, heat treatment, lubrication, etc.) to prevent fretting. This article presents a study of the impact of thermal and thermochemical heat treatments of steels used in power transmissions on the appearance, morphology and intensity of corrosion fretting.Among the materials and heat treatments commonly used in mechanical transmissions (NF EN 683, ISO 6336-5), the following variants were studied: through-hardened steels (42CrMo4, 100Cr6), surface-hardened steels (42CrMo4), case-hardened steels (20MnCr5) and nitrided steels (42CrMo4). These variants are compared using a standardized ASTM G204 test, which involves oscillating a pressurized, lubricant-free pin (100Cr6) on a plate (the tested variant) for 24 hours. The peak-to-peal slip amplitude range is set at 50µm or 100µm. Tangential forces during testing, then the volume loss of pin and plate after testing, were measured, analysed and compared. The experimental study reveals wear resistance and depend on heat and thermochemical treatment as well as slip amplitudes. Through hardened 100Cr6 has better fretting resistance than nitrided 42CrMo4 for 50µm amplitude, but the results are completely reversed at 100µm amplitude.

Fatigue life prediction of the nitrided steel by multiaxial high cycle fatigue criteria

The present study aims to predict the fatigue strength of ion-nitrided 42CrMo4 steel, using multiaxial high cycle fatigue (HCF) criteria and considering the effects of stabilized residual stresses and surface hardening. The predicted fatigue strength was compared to experimental data obtained after three-points bending fatigue tests at two stress ratios (0.1 and 0.5) and for notched (Kt = 1.6) nitrided and untreated specimens. A 3D finite element (FE) model of a three-point bending fatigue test was developed under ABAQUS software in order to determine the actual applied cyclic stress state at the notch. The results show that ion-nitriding treatment led to 32% improvement in the fatigue strength at 106 cycles compared to the untreated material. This improvement is explained by the advantageous effect of ion-nitriding treatment in terms of compressive residual stresses and surface layer hardening. Both stabilized residual stress state and hardening effects were successfully implemented into various multi-axial HCF criteria, including Sines, Crossland, Dang Van and Matake criteria. A sensitivity analysis has shown that Crossland criterion has permitted to predict the fatigue limits in accordance with the experimental results.

Leveraging Deep Neural Networks for Estimating Vickers Hardness from Nanoindentation Hardness.

This research presents a comprehensive analysis of deep neural network models (DNNs) for the precise prediction of Vickers hardness (HV) in nitrided and carburized M50NiL steel samples, with hardness values spanning from 400 to 1000 HV. By conducting rigorous experimentation and obtaining corresponding nanoindentation data, we evaluated the performance of four distinct neural network architectures: Multilayer Perceptron (MLP), Convolutional Neural Network (CNN), Long Short-Term Memory network (LSTM), and Transformer. Our findings reveal that MLP and LSTM models excel in predictive accuracy and efficiency, with MLP showing exceptional iteration efficiency and predictive precision. The study validates models for broad application in various steel types and confirms nanoindentation as an effective direct measure for HV hardness in thin films and gradient-variable regions. This work contributes a validated and versatile approach to the hardness assessment of thin-film materials and those with intricate microstructures, enhancing material characterization and potential application in advanced material engineering.

Analysis of Pre-Treatment Processes to Enable Electroplating on Nitrided Steel

Nitrided steel is being used to increase the lifetime and wettability of selective soldering nozzles. In this environment, the liquid solder wets to the surface of the nozzle to enable control of the solder flow during the soldering process. Pre-treatment is a key step in the processing of parts for electroplating. Pre-treatment usually involves degreasing and acidic pickling steps in order to remove adsorbed oil-based compounds and oxides respectively. These steps ensure a well-structured and adherent electroplated coating to the part.Surface treatments such as nitriding alter the surface composition of steels and thereby change the conductivity/surface activity. Typically, a nitrided surface contains a dual-phase surface layer followed by a diffusion zone consisting of the formed nitrides and finally a transition zone to the bulk material. Generally, this surface treatment is performed to harden materials without the risk of dimensional changes. For a selective soldering application, it reduces the dissolution of material into the solder during operation while also improving the wetting of the nozzle.The electroplated coatings for the selective soldering nozzles consist of 10 microns of nickel and 10 microns of tin. This structure allows for near-instant wetting and use of the nozzle. Furthermore, the electroplated layers provide corrosion protection for the nozzle ensuring no oxide or scale layers will form that may require flux for cleaning.A range of chemical and electrochemical pre-treatment steps were explored to prepare and optimally activate the nitride-hardened steel surfaces for electroplating. The processes included: hot degreasing and electrolytic degreasing with alkaline detergents; electrolytic descaling in a solution containing sodium hydroxide; chemical pre-descaling process with potassium permanganate; varying the compositions of pickling in inorganic acids; different formulations for nickel strike electrolytes for plating onto ferrous alloys.Mass loss measurements provided an estimation of the thickness of the material removed due to acid pickling. Scanning electron microscopy was employed to assess changes in the surface due to the pre-treatment. Open circuit potential measurements were applied to measure the surface activity before any pre-treatment and also the change in surface conductivity/activity post-treatment. Nanoindentation measurements were used to assess the change in surface hardness as a result of the nitriding treatment and also to check for the presence of the remaining hardened nitrided layer after pre-treatment. Glow discharge optical emission spectroscopy was utilised to study the elemental depth profile of the nitrided parts. Crystalline structure was studied through x-ray diffraction. After pre-treatment, a Woods nickel strike was applied to prepare the surface for further electroplating with bright tin. SEM analysis of the cross-sections of the coated specimens was used to analyse the coating microstructure. Thickness of the electrodeposited coatings were confirmed with x-ray fluorescence. Thermal shock tests were performed to confirm that the adhesion of the coating was sufficient.Approximately half of the nitrided layer was removed by pre-treatment in order to activate the surface for electroplating. More severe pre-treatment was required compared to electroplating non-hardened parts to activate the surface. Surface conductivity/surface activity was altered as measured by OCP resulting from the pre-treatment.This work has analysed the surface modification of nitride-hardened steels during the pre-treatment steps required to initiate electroplating and has shown that it is possible to prepare nitride-treated steels for electroplating. The results can be used to develop more optimal pre-treatment processes for electroplating nitrided steels.

Formation of expanded phases in ferritic stainless steel nitrided at low temperatures

Nitriding treatments at low temperatures (<450 °C) are receiving increasing interest for the surface engineering of stainless steels due to the possibility of producing supersaturated solid solutions of nitrogen in the iron-based lattices, known as “expanded” phases. In this study this treatment was applied to AISI 430 ferritic stainless steel with the aim of clarifying the characteristics of the modified surface layer, and in particular the microstructure and phase composition. The formation of expanded ferrite caused high compressive stresses, so that local plastic deformation phenomena occurred, observable as microstructural changes (slip lines, grain swelling) both at the surface and in the section of the samples. Moreover, the formation of a nitrogen-containing hexagonal close-packed phase, dissimilar to ε-nitride, was reported for the first time for low-temperature nitrided ferritic stainless steels. It is suggested that this phase might be a N-rich expanded ε′-martensite, which formed from expanded ferrite due to a bcc-to-hcp displacive transformation and it remained in the microstructure owing to the residual compressive stresses and nitrogen and chromium solubilization. The presence of this phase contributed to the increase of surface microhardness together with expanded ferrite. The assessment of the corrosion behaviour in 3.5 wt% NaCl aerated solution by means of electrochemical impedance spectroscopy analysis and potentiodynamic measurements showed that, when the modified surface layer consisted only of expanded ferrite, impedance values and corrosion potential had a marked increase and corrosion current density decreased, as compared to those of the untreated steel, suggesting an enhancement of the resistance to general corrosion. On the contrary, when a heterogeneous modified layer formed (expanded ferrite and N-rich expanded ε′-martensite), a worsening of corrosion resistance was observed.

Effect of Rapid Hollow Cathode Plasma Nitriding Treatment on Corrosion Resistance and Friction Performance of AISI 304 Stainless Steel.

Low-temperature plasma nitriding of austenitic stainless steel can ensure that its corrosion resistance does not deteriorate, improving surface hardness and wear performance. Nevertheless, it requires a longer processing time. The hollow cathode discharge effect helps increase the plasma density quickly while radiatively heating the workpiece. This work is based on the hollow cathode discharge effect to perform a rapid nitriding strengthening treatment on AISI 304 stainless steels. The experiments were conducted at three different temperatures (450, 475, and 500 °C) for 1 h in an ammonia atmosphere. The samples were characterized using various techniques, including SEM, AFM, XPS, XRD, and micro-hardness measurement. Potentiodynamic polarization and electrochemical impedance spectroscopy methods were employed to assess the electrochemical behavior of the different samples in a 3.5% NaCl solution. The finding suggests that rapid hollow cathode plasma nitriding can enhance the hardness, wear resistance, and corrosion properties of AISI 304 stainless steel.

Open-atmosphere laser nitriding of austenitic steels to form wear-resistant surfaces

This study presents an interesting result based on the laser beam irradiation of austenitic steels in an open atmosphere, which enables the formation of a surface layer comprising a nitrogen solid solution rather than an oxide. First, a focused nanosecond pulsed Nd:YAG laser beam with a laser energy of 400 mJ·pulse−1 was used to irradiate an AISI 316 stainless steel. This formed a surface layer of ~3 μm thickness with ~12 at.% nitrogen solid solution, thereby enhancing the hardness of the AISI 316 stainless steel surface to ~380 HV, nearly twice that of the untreated surface. Consequently, wear resistance was improved by preventing plastic deformation and abrasive wear. Thereafter, similar laser beam irradiation of Inver42® and Kovar® steels resulted in the formation of nitrogen solid solution layers with a thickness of ~1.5 μm, which is lower than that of AISI 316 steel. Furthermore, their nitrogen contents were reduced to ~6 at.%. Consequently, the improvement in the surface hardness of the Inver42® and Kovar® steels was less than that of the AISI 316 stainless steel. These differences were attributed to their alloy compositions; for instance, Cr, which has a high affinity for nitrogen, might trap the available nitrogen, thereby contributing to an increase in the nitrogen content.