AISI 440C Research Articles

Frictional behavior between silicon and steel coated with graphene oxide in dry sliding and water lubrication conditions

With growing concern over environmental problems, green technologies associated with reducing pollution have been rapidly progressing to attain a sustainable future. Among numerous green technologies currently under development, water lubrication technology that can replace the use of conventional oil lubricants can be a promising technology that may lead to huge benefits with respect to environmental and economic issues. In this work, good-lubricating performance was achieved by using reduced graphene oxide (rGO) coating on AISI 440C stainless steel (SS) ball that was slid against a silicon (Si) specimen under water lubrication condition. Compared to the sliding tests performed in dry condition, the friction coefficient of the rGO coated SS ball slid against the Si specimen under water lubrication condition could be reduced by 12 times. Also, it was shown that friction coefficient of the uncoated SS ball slid against the Si specimen in water and dry conditions were relatively higher than that of the sliding test conducted with the rGO coated SS ball in water lubrication. The experimental results demonstrated that the rGO coating on SS can effectively lower the friction in water lubrication conditions. This work are expected to aid in the development of environmental-friendly lubrication technology for mechanical components.

Reduction of Friction of Metals Using Laser-Induced Periodic Surface Nanostructures

We report on the effect of femtosecond-laser-induced periodic surface structures (LIPSS) on the tribological properties of stainless steel. Uniform periodic nanostructures were produced on AISI 304L (American Iron and Steel Institute steel grade) steel surfaces using an 800-nm femtosecond laser. The spatial periods of LIPSS measured by field emission scanning electron microscopy ranged from 530 to 570 nm. The tribological properties of smooth and textured surfaces with periodic nanostructures were investigated using reciprocating ball-on-flat tests against AISI 440C balls under both dry and starved oil lubricated conditions. The friction coefficient of LIPSS covered surfaces has shown a lower value than that of the smooth surface. The induced periodic nanostructures demonstrated marked potential for reducing the friction coefficient compared with the smooth surface.

Experimental investigation of external surface finishing of AISI 440C stainless steel cylinders using the magnetic abrasive finishing process

Magnetic abrasive finishing (MAF) is one of the advanced machining processes implementing the material removal in micro dimensions using the magnetic field force and magnetic abrasive particles (MAPs). In this process, the machining forces are low, the surface defects such as micro-cracks are so small and a desirable smooth surface is obtained. In this paper, the effects of parameters such as working gap, workpiece rotational speed, and the material removal mechanism (injecting the abrasive slurry of SiC and Al2O3, and diamond paste) on the surface roughness has been experimentally investigated in the MAF process on the external surface of the AISI 440C stainless steel cylinders. To do the experiments, a setup was designed and manufactured, and the experiments have been implemented according to the design of experiments (DOE) and the full factorial method. The experimental data were analyzed using the analysis of variance (ANOVA). The experimental data analysis showed that the working gap and the workpiece rotational speed have a significant effect on improving the surface roughness. The obtained surface roughness under the conditions of experimental working gap of 2 mm, the workpiece rotational speed of 355 rpm, using the Al2O3 and SiC abrasive slurry injection, and diamond paste has improved as 20, 30, and 50 %, respectively. The images of scanning electron microscopy (SEM) taken from the workpiece surface texture before and after the process confirm the obtained results.

Characterization and Rockwell-C adhesion properties of chromium-based borided steels

In this study, adhesion properties of boride layers formed on the surface of AISI 52100, AISI 5140, AISI 440C, AISI 420 and AISI 304 steels were investigated. Boronizing treatment was carried out in Ekabor-II powders at the temperatures of 850 and 950 °C for 4 h. The properties of boride layers were evaluated by optical microscopy, SEM, X-ray diffraction and micro-Vickers hardness tester. The Daimler-Benz Rockwell-C adhesion test was used to assess the adhesion of boride layers. Test result showed that adhesion of boride layers depended on the dual-phase structure. The stresses at the FeB/Fe2B interphase caused delamination failure and poor interphase adhesion with increase in the depth of hard and brittle FeB-based layer.

Surface Carbon Chemical States of Ion Implanted AISI 440C Martensitic Stainless Steel

Carbon atoms segregate in the surface region for polished AISI 440C stainless steel. After ion implantation, the surface carbon atoms exist in different forms. To elucidate their existence, surface structures and carbon chemical states of unimplanted, N+ implanted, Ti+ implanted and N+/Ti+ co-implanted samples were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that various phases form in the surface or subsurface region after ion implantation, while the surface topography of the samples remains intact. For polished unimplanted sample, besides some Fe3C phase and C-C phase, CrxCy phase dominates its surface region. Little change of carbon chemical states occurs after N+ ion implantation. For Ti+ implanted sample, besides some metal oxycarbide phases, most carbon amorphous phases form in surface region. Concerning N+/Ti+ co-implantation, CrxCy, compound as well as Fe3C phase dominates the surface region while no C-C phase is found. In addition, compared with single-ion implantation, N+/Ti+ co-implantation would increase the ion implantation depth significantly. The formed phases of the carbon atoms play an important role in affecting the surface properties of AISI 440C stainless steel.

Fretting wear behavior of Zn–Ni alloy coatings

Cadmium coatings are used in the aerospace industry primarily as a corrosion resistant plating, but also in applications where tribological properties are also important. Due to the carcinogenic nature of Cd, many coatings have been proposed as replacements, with Zn–Ni being the leading candidate. In this study, we examine two Zn–Ni coatings with differences in their surface roughness and their content of through thickness defects, including pores and cracks. The morphological differences between the coatings had a noticeable effect on their fretting wear behavior.A customized tribometer, with a reciprocating rounded pin (AISI 440C steel) on flat (Zn–Ni) geometry, was used to perform fretting wear tests. The two morphologically different Zn–Ni coatings were tested at room temperature using ±70, 100 and 150μm displacements and 133N and 447N constant normal loads. The surface of the wear scar was analyzed using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy for changes in morphology and chemistry. Wear scar depth was measured from surface profiles obtained using confocal microscopy.Hysteresis fretting loops of the tests showed that for both coatings, at ±70μm displacement remains in no slip condition, at ±100μm in the mixed slip condition, and at ±150μm displacement remains in gross slip condition. Although the coatings had similar stick–slip behavior, the smoother coating has a slower progression of wear from the no slip to gross slip conditions than the rougher coatings. Also, differences in the wear scar morphologies are attributed to the differences in the coating morphologies, which resulted in different wear and velocity accommodation mechanisms.

Microstructural Changes Induced by Ultrashort Pulsed Lasers in Microdrilling of Fuel Nozzles

Microholes for gasoline direct injection (GDI) nozzles were obtained in martensitic stainless steel AISI 440C with conventional micro-EDM and two laser based processes: water-jet guided μs-laser and fs-laser. Since the analyzed drilling methods heavily differ for their thermal input on materials, the three processes were compared from the perspective of the microstructural changes induced in the bulk material after drilling. Moreover, the sharpness of the edges was taken into account as distinctive feature for a comparison among the three processes, being the spray atomization maximized by a cavitation process inside the microhole.A tailored procedure was optimized to prepare the samples for Scanning Electron Microscopy (SEM) and metallographic analyses. The cross sections of micro-EDM drilled samples revealed the presence of a recast (white) layer of 1-2μm in thickness even using the lowest spark energy in the tested range. Samples drilled by water-jet guided μs-laser are affected by the same phenomenon, with an even more pronounced effect. Moreover, they showed the extrusion of the melt material along the hole axis under the action of the water-jet conveying the beam. The extremely fast cooling of this layer also makes the machined surfaces prone to cracking. Conversely, metallographic analysis of cross sections of ultrashort pulsed laser drilled samples, showed no modification of the base metal microstructure in the sub-surface regions, thus testifying that the fs-pulsed laser drilling was an almost pure ablation process and not affected by a remarkable liquid phase as for the other two thermal processes. Periodicity and dimensions of laser induced periodic surface structures (LIPSS) generated by ultrashort pulsed laser were characterized by means of Scanning Electron Microscopy. SEM analysis of the microhole edges revealed burrs for the water-jet guided μs-laser while radii of 3-4μm for micro-EDM and less than 1μm for fs-lasers were measured.

A study on the control of melting ratio to increase mechanical properties of laser welded joints between AISI 440C and AISI 430F

Abstract Laser beam welding of dissimilar AISI 440C and AISI 430F stainless steels was investigated in a circular constrained configuration. The beam incidence angle and the offset of the focusing position respect to the contact point between the two materials were used as main control parameters to vary the melting ratio inside the seam. The objective of the study is twofold: to avoid surface microcracks related to the high percentage of carbon of the martensitic steel and to enhance the shear strength of the weld by making it less brittle. To reach this scope the effects of incidence angle and offset on weld bead geometry and melting ratio were studied by means of metallographic analyses, microstructure and microhardness characterization. As last step, the weld mechanical strength was tested by tensile-shear stress test on the whole seam. Experiments demonstrated that varying incidence angle and offsetting the focal position is a reliable method to modify the melting ratio and maintaining the expected resistance length at the material interface, as well. It was found that increasing the percentage of ferritic steel into the joint has beneficial effects on the weld quality and on the shear resistance. The critical carbon content determining the mechanical properties in the fusion zone can be calculated by taking into account the melting ratio.

Pack carburisation of commercially pure titanium with limited oxygen diffusion for improved tribological properties

In the present work a new pack carburising surface treatment method has been developed, whereby oxygen diffusion and carburisation of commercially pure titanium was undertaken. Pack carburisation was carried out with a limited amount of oxygen, at a temperature of 925°C for 20h. The carburising process resulted in a multilayer structure comprising a titanium carbide (TiC) network layer atop of a relatively thick α-titanium oxygen diffusion zone (α-Ti(O)). Initial tribological tests demonstrated that the new surface treatment can significantly enhance the tribological properties of titanium, in terms of much reduced friction, improved wear resistance and enhanced load bearing capacity. The TiC surface structure offers enhanced hardness (2100HV) and low friction coefficient (μ≈0.2) when in dry sliding contact with an alumina (Al2O3) ball, while the thick oxygen diffusion zone offers much enhanced load bearing capacity. When compared with untreated Ti, thermally oxidised titanium (TO-Ti) and hardened AISI 440C stainless steel, the carburised titanium allowed for a greatly improved friction and wear response.

Influence of Deep Cryogenic Treatment on the Mechanical Properties of AISI 440C Bearing Steel

This research paper focuses on the influence of shallow and deep cryogenic treatment on the mechanical properties of AISI 440C bearing steel. Hardness of this material is increased by 7% when subjected to Deep Cryogenic Treatment (DCT); and by 4% for Shallow Cryogenic Treatment (SCT) compared to the Conventional Heat Treatment (CHT). ‘ImageJ’ software has been used to analyse the optical microscope image of the conventional and cryogenic treated samples to estimate the retained austenite percentage. The retained austenite percentages of these samples were 29%, 8% and 5.7% for the conventional, shallow cryogenic and deep cryogenic treated samples respectively. DCT sample shows relatively higher hardness than CHT samples due to higher conversion of retained austenite to martensitic structure. DCT sample shows minor increment in hardness when compared to SCT. DCT and SCT samples show improved hardness by 7% and 4% than that of the CHT sample. Fractography analysis of the cryogenically and conventionally heat treated bearing steel were performed using Scanning Electron Microscope (SEM). SEM analysis clearly indicates the formation of flat facets in SCT specimens and micro cracks in DCT specimens.

Excellent Vacuum Tribological Properties of Pb/PbS Film Deposited by Rf Magnetron Sputtering and Ion Sulfurizing

Soft metal Pb film of 3 μm in thickness was deposited on AISI 440C steel by RF magnetron sputtering, and then some of the Pb film samples were treated by low-temperature ion sulfurizing (LTIS) and formed Pb/PbS composite film. Tribological properties of the Pb and Pb/PbS films were tested contrastively in vacuum and air condition using a self-developed tribometer (model of MSTS-1). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to analyze the microstructure and chemical construction of the films and their worn surfaces. The results show that a mass of Pb was changed to PbS during the process of LTIS. In air condition, owing to the severe oxidation effect, pure Pb film showed relatively high friction coefficients (0.6), and Pb/PbS composite film also lost its friction-reduction property after sliding for a short time. In a vacuum, the average friction coefficients of Pb film were about 0.1, but the friction coefficient curve fluctuated obviously. And the Pb/PbS composite film exhibited excellent tribological properties in vacuum condition. Its friction coefficients keep stable at a low value of about 0.07 for a long time. If takes the value of friction coefficients exceeding 0.2 continuously as a criterion of lubrication failure, the sliding friction life of Pb/PbS film was as long as 3.2 × 10(5) r, which is 8 times of that of the Pb film. It can be concluded that the Pb/PbS film has excellent vacuum tribological properties and important foreground for applying in space solid lubrication related fields.

Potential-Controlled Boundary Lubrication of Stainless Steels in Non-aqueous Sodium Dodecyl Sulfate Solutions

In aqueous solutions, sodium dodecyl sulfate (SDS) surfactant can form a boundary film on metal surfaces to provide lubrication for sliding surfaces in contact. Previous studies have demonstrated that the boundary lubrication of SDS film can be inhibited or enhanced substantially by changing the surface potential of the rubbing metal surfaces. In this study, the SDS surfactant was added to a non-aqueous base fluid, propylene carbonate (PC), and the boundary lubrication behaviors of the solution for stainless steels were investigated under different potential conditions. Friction measurement, electrochemical impedance spectroscopy, cyclic voltammetry, and electrochemical quartz crystal microbalance techniques were employed to investigate the lubricating performance and adsorption film of the sodium dodecyl sulfate (SDS) film on two kinds of steels (AISI 316L, AISI 440C) in propylene carbonate (PC) solution. Similar to aqueous SDS solutions, the lubricating performance of the SDS/PC solution depends upon the electrode potential within the potential range from −1.5 to +1.5 V versus Ag/AgCl, which suggests the potential-dependent reversible change in the adsorbed film. When the potential is positive, both friction and wear of the tested stainless steels are relatively lower due to the presence of the adsorbed SDS film. As the potential is shifted to the negative regime, the DS chains in the adsorbed film are replaced by the PC molecules gradually, and friction coefficient increases by 100 % or more, depending on the load condition and the hardness of the stainless steels.

Tribological Behavior of Ion Implanted AISI 440C Stainless Steel under Oil Lubricated Condition

The tribological behaviors of nitrogen and titanium ion implanted AISI 440C stainless steel were studied by using an oscillating ball-on-disk tribometer under oil lubricated condition. The results showed that the ion implantations would significantly decrease the friction coefficient of the samples. To interpret the effect mechanism of the ion implantation on tribological performance, the surface morphology and oil wettability of the ion implanted samples were investigated by using a three-dimensional white interferometer and a contact angle analyzer, respectively. In addition, the surface structures and components of the samples were analyzed by using XRD and XPS techniques. The results indicated that the low friction coefficients of the ion implanted samples can be attributed to the new phases formed on the sample surfaces. For nitrogen ion implanted sample, the metal nitrides, supersaturated interstitial N and some C-O-N compounds appear on the sample surface. For titanium ion implanted sample, apart from TiO2and TiC phases form at the AISI 440C steel surface. Those components increase the surface energy of the AISI 440C steel and are in favor of the formation of the thin oil film.

Effect of Deposition Time on Properties of ZrO<sub>2</sub> Coating Prepared Using Electrolytic Method

AISI 440C martensitic stainless steel is one of the most widely studied engineering materials for its tribological properties. It is capable of attaining the best mechanical properties such as high strength and hardness compared to other martensitic grades. Unfortunately, the corrosion resistance of this 440C steel is the lowest among the stainless group, which results in the precipitation of carbide phases. AISI 440C were coated using electrolytic ZrO2 layer deposition method in ZrO(NO3)2 aqueous solution. In order to preserve the high mechanical properties of this steel, various heat treatment processes applied to the coated samples. After drying and annealing, the ZrO2 coated samples were evaluated using SEM, hardness tests and corrosion tests. Some mud-crack had been indicated in all samples. However, it become more homogeneously on the sample which undergoes longer deposition time. This difference resulted in a significant improved on corrosion resistance of ZrO2 coated sample.

Early Stages of the Wear Behavior of AISI 440C Stainless Steel under Rolling Contact in Water

In the present work, rolling contact fatigue (RCF) tests in water were performed on AISI 440C stainless steels under different loading. Each test was interrupted at 3.6×104, 7.2×104, 1.44×105, 2.16×105, 2.88×105 and 2.88×105 rotating cycles and the wear track at different stages was observed by using a 3D laser confocal microscope. The wear loss at 2100 N was a significantly higher compared to 500 N or 1000 N. The contact surface roughness in samples tested at 2100 N increased during the rolling contact and severe adhesion wear was present at the entire surface. In case of 500 and 1000 N tests, the surface roughness remained low with mild adhesion wear occurring. It is concluded that adhesion force levels are higher under high load rolling contact. They greatly influence the surface conditions and cause high wear loss.

Microstructures and properties of friction surfaced coatings in AISI 440C martensitic stainless steel

While martensitic stainless steel AISI 440C is an attractive material for wear protection in many industrial applications, it is difficult to realize satisfactory coatings in this material using conventional weld overlay processes. Friction surfacing, a promising solid-state process, can help in this regard. In the current study, alloy 440C coatings were successfully made on low carbon steel substrates using friction surfacing. Bend and shear tests on coated specimens indicated excellent coating/substrate bonding. Microstructures, corrosion behavior, and wear performance of these coatings were compared with standard heat treated alloy 440C bulk material. While friction surfaced coatings in alloy 440C exhibited superior corrosion resistance to standard heat treated alloy 440C bulk material, their wear resistance was found to be somewhat inferior. Apart from these studies, experiments were conducted to assess the potential of the process for wide area coverage. Studies show that it is possible to achieve well-bonded coatings consisting of multiple overlapping tracks with excellent inter-track bonding. Overall, the current study demonstrates that friction surfacing is a very useful process for producing wear resistant coatings in difficult-to-fusion-deposit materials such as alloy 440C martensitic stainless steel.

Influence of deposition temperature and pressure on microstructure and tribological properties of arc ion plated Ag films

The films deposited at low temperature (LT-films) have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited at room temperature. Studies on the tribological properties of LT-films are rarely reported in available literatures. In this paper, the structure, morphology and tribological properties of Ag films, deposited at LT (166 K) under various Ar pressures on AISI 440C steel substrates by arc ion plating (AIP), are studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and a vacuum ball-on-disk tribometer, and compared with the Ag films deposited at RT (300 K). XRD results show that (200) preferred orientation of the films is promoted at LT and low Ar pressure. The Crystallite sizes are 70 nm–80 nm for LT-Ag films deposited at 0.2 Pa and 0.8 Pa and larger than 100 nm for LT-Ag films deposited at 0.4 Pa and 0.6 Pa, while they are 55 nm–60 nm for RT-Ag films deposited at 0.2 Pa–0.6 Pa and 37 nm for RT-Ag films deposited at 0.8 Pa. The surfaces of LT-Ag films are fibre-like at 0.6 Pa and 0.8 Pa, terrace-like at 0.4 Pa, and sphere-like at 0.2 Pa, while the surfaces of RT-Ag films are composed of sphere-like grains separated by voids. Wear tests reveal that, due to the compact microstructure LT-Ag films have better wear resistances than RT-Ag film. These results indicate that the microstructure and wear resistance of Ag films deposited by AIP can be improved by low temperature deposition.

Diffusion kinetics of borided AISI 52100 and AISI 440C steels

In this study, the case properties and diffusion kinetics of AISI 440C and AISI 52100 steels borided in Ekabor-II powder were investigated by conducting a series of experiments at temperatures of 1123, 1173 and 1223 K for 2, 4 and 8 h.The boride layer was characterized by optical microscopy, X-ray diffraction technique and micro-Vickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe2B and CrB compounds.The thickness of boride layer increases by increasing boriding time and temperature for all steels. The hardness of the boride compounds formed on the surface of steels AISI 52100 and AISI 440C ranged from 1530 to 2170 HV0.05 and 1620 to 1989 HV0.05, respectively whereas Vickers hardness values of untreated steels AISI 440C and AISI 52100 were 400 HV0.05 and 311 HV0.05, respectively. The activation energies (Q) of borided steels were 340.426 kJ/mol for AISI 440C and 269.638 kJ/mol for AISI 52100. The growth kinetics of the boride layers forming on the AISI 440C and AISI 52100 steels and thickness of boride layers were also investigated.

Microstructure and sliding wear resistance of an Al–12 wt.% Si/TiC laser clad coating

Metal matrix composite coatings consisting of an Al–12wt.% Si-alloy matrix reinforced with TiC were prepared by laser cladding from mixtures of Al–12wt.% Si alloy and TiC powders. For the processing parameters used (power density 200MW/m2 and interaction time 0.3s), a small proportion of TiC dissolves in the melt, resulting in a microstructure composed of 34vol.% of TiC and 3vol.% of Ti3SiC2 particles dispersed in a matrix consisting of proeutectic α-Al dendrites and α-Al+Si eutectic. The coating material presents a hardness of 165HV and a wear coefficient of 2.24×10−5mm3/(Nm) in ball-on-plate dry sliding wear tests, using quenched and tempered AISI 440C martensitic stainless steel as the counterbody material. Analysis of the worn surfaces showed that the sliding motion of the contacting bodies leads to the formation of a tribolayer consisting of Fe oxides, as well as metallic phases. On the basis of theoretical calculations it is suggested that the primary material removal mechanism involves the propagation of cracks through the thickness of this tribolayer, followed by crack channeling and debonding of tribolayer fragments.

Tribological behavior of thick CrN coatings deposited by modulated pulsed power magnetron sputtering

Thick CrN coatings (up to 55 μm) have been deposited on different substrate materials (WC–Co, M2 steel, AISI 440C steel, AISI 304 steel, Al–Si eutectic alloy, and copper) using the modulated pulsed power (MPP) magnetron sputtering technique at a high deposition rate of 10 μm/h. The thick CrN coatings have been characterized for the microstructure, mechanical and tribological properties. The adhesion of the coatings with different thicknesses on different substrates was evaluated using progressive scratch tests. The dry sliding wear tests for the thick coatings deposited on the AISI 440C substrate were carried out using a ball-on-disk microtribometer. The wear tests were conducted on the 20 μm thick MPP CrN coatings using different ball materials (α-Al 2O 3, WC–Co, AISI 440C steel, AISI 302 steel, 100Cr6 steel, and brass), different applied loads (5–40 N) and sliding speeds (5–50 cm/s) for a maximum sliding distance up to 10 km. The coating wear tracks and ball wear scars were examined using scanning electron microscopy. The thick CrN coatings showed coefficients of friction in the range of 0.48–0.94 as sliding against different materials and under different test conditions. The wear rate of the coatings increased with the increases in the applied load and sliding speed, which is related to an increase in the plowing force (plastic deformation of the substrate) and an increase in the flash temperature, respectively. The wear rates of the 20 μm thick MPP CrN coating are in the range of 1 × 10 − 7 to 5.5 × 10 − 7 mm 3 N − 1 m − 1 . This study has demonstrated that thicker CrN coatings exhibited larger load and sliding speed capacities, which allow them to be operated under more severe conditions, e.g. higher loads, sliding speeds, and operating temperatures.