Unimplanted Steel Research Articles

Characterization of Surface Composition and Microstructure of H21 Steel Implanted Using Masking Ti-Implantation

Ti ions were implanted into H21 steel to improve the surface structure of oxides in H21 steel. The wear characteristics of the implanted steel was measured and compared to the performance of the un-implanted steel by a line-cutting apparatus and an optical interference microscope. The Ti concentration depth profile of the implanted steel was measured by Rutherford backscattering spectroscopy (RBS). The structure and composition of oxides were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The results showed that the improved wear resistance of the implanted steel was mainly due to the structure and composition changes of the surface oxides after Ti ion implantation.

Friction characteristics of a phosphorous-containing steel surface derived from ion implantation

Phosphorous (P) ion implantation was performed on a steel substrate to investigate the effect of the P implantation on the friction characteristics of steel lubricated with oil. To determine the characteristics of the P-implanted layer, several kinds of surface analyses were carried out, resulting in a correlation between the X-ray photoelectron spectroscopy depth profile and the thickness from spectroscopic ellipsometer. A three balls-on-disc tribometer was employed with sliding speeds ranging from 3 mm/s to 40 cm/s. The friction coefficient of the P-implanted steel was relatively lower at speeds below 10−1 m/s, compared with the unimplanted steel. This could account for both the sacrificing nature and the adhesion behaviour of the P-implanted layer.

GS1-1 リンイオン注入された鋼のトライボロジー特性(一般セッション)

Phosphorous (P) ion implantation was performed on a steel substrate to investigate the effect of the P implantation on the friction characteristics of steel lubricated with oil. To determine the characteristics of the P-implanted layer, several kinds of surface analyses were carried out, resulting in a correlation between the M'S depth profile and the thickness from spectroscopic ellipsometer. A 3 balls-on-disk tribometer was employed with sliding speeds ranging from 3 mm/s to 40 cm/s. The friction coefficient of the P-implanted steel was relatively lower at speeds below 10-1 m/s, compared with the unimplanted steel. This implied that the P implantation was effective in reducing friction.

Effect of chromium and nitrogen co‐implantation on the characteristics of the passive layer developed on austenitic and duplex stainless steels

AbstractAISI 304L and SAF 2205 stainless steel samples were implanted with chromium plus nitrogen at saturation dose in order to improve their hardness and wear properties. Consequently, the passive layer is modified so that besides the detected presence of CrN, a clear decrease in the amount of Fe oxides forming the passive layer is detected in both steels; this effect is especially important in AISI 304L. Co‐implantation also causes Ni0 enrichment present at the metal/oxide of unimplanted steels to disappear. The induced changes in the electrochemical response in NaOH solution are finally considered. Copyright © 2008 John Wiley & Sons, Ltd.

Nucleation and growth of amorphous carbon film on tungsten-implanted stainless steel substrates

Amorphous carbon (a-C) films were deposited on W-implanted (20 kV, 3 × 10 17 ions cm − 2 ) and un-implanted steel substrates by plasma immersion ion implantation and deposition (PIII&D). The W implantation pretreatment changes the surface structure and impacts film nucleation. Consequently, the growth mechanism of the a-C film is altered resulting in different surface morphologies and roughnesses even though the films deposited on the un-implanted steel substrates possess similar a-C structures as revealed by Raman spectroscopy. The structural differences are probed by X-ray photoelectron spectroscopy and X-ray diffraction. Moreover, microstructural observations were carried out by transmission electron microscopy. A model based on the statistical formation theory is proposed to explain the growth of the a-C films on the implanted and un-implanted substrates.

Influence of chromium and cerium implantation in the electrochemical development of passive layers on AISI 304L

In this work X-ray photoelectron spectroscopy studies and electrochemical techniques are combined to elucidate the effect of Ce and Cr implantation in the formation and evolution of passive layers generated by potentiodyinamic cycling on AISI 304L steel in alkaline medium. Cerium implantation promotes the formation of a thinner and more protective film on the steel. This fact, noticed in X-ray photoelectron spectroscopy (XPS) analysis, is reflected in the voltammograms by an important decrease of the magnetite formation and Cr3+/Cr6+ oxidation peak and, in the electrochemical impedance spectroscopy (EIS) diagrams, as the disappearance of one time constant. Chromium implantation contributes also to the generation of a thinner film, but more defective than in the case of cerium implantation. These differences are demonstrated in both electrochemical and surface analytical techniques. In the voltammetric curves, the diminution of the iron oxides signal is less notorious and an important increasing in the Cr3+/Cr6+ oxidation peak is registered. The EIS results show the persistence of the same number of time constants detected in the unimplanted steel.

Análisis de las películas pasivas generadas en aceros inoxidables implantados con cromo

This work studies the effect of chromium implantation on the development of passive layers generated electrochemically in alkaline medium over two stainless steels. The XPS analyses show that the layers generated on the implanted steels present less thickness together with similar composition compared to the unimplanted steels layers. However, SEM micrographs show that the layers grown on implanted steels present more defects and less adherence that the films on unimplanted steels. These changes together with the results obtained by Cyclic Voltammetry suggest an oxide structure modification, lattice structure or cristalinity state.

Influence of chromium and cerium implantation in the electrochemical development of passive layers on AISI 304L

In this work X-ray photoelectron spectroscopy studies and electrochemical techniques are combined to elucidate the effect of Ce and Cr implantation in the formation and evolution of passive layers generated by potentiodyinamic cycling on AISI 304L steel in alkaline medium. Cerium implantation promotes the formation of a thinner and more protective film on the steel. This fact, noticed in X-ray photoelectron spectroscopy (XPS) analysis, is reflected in the voltammograms by an important decrease of the magnetite formation and Cr 3+/Cr 6+ oxidation peak and, in the electrochemical impedance spectroscopy (EIS) diagrams, as the disappearance of one time constant. Chromium implantation contributes also to the generation of a thinner film, but more defective than in the case of cerium implantation. These differences are demonstrated in both electrochemical and surface analytical techniques. In the voltammetric curves, the diminution of the iron oxides signal is less notorious and an important increasing in the Cr 3+/Cr 6+ oxidation peak is registered. The EIS results show the persistence of the same number of time constants detected in the unimplanted steel.

Investigation on the tribology of Zr ion implanted tool steel

AISI D3 tool steel was ion implanted with zirconium and the improvement in surface tribological properties investigated. The Zr ion implantation was done using a metal vapor vacuum arc (Mevva) broad-beam ion source, with a mean ion energy of 130 keV and at doses of 3.6×10 16, 5×10 16 and 1×10 17 ions/cm 2. Wear, friction and hardness of the implanted samples were measured and compared to the performance of unimplanted steel. The wear resistance was increased by about a factor of two, the friction remained about the same or was possibly increased by a small amount and the near-surface hardness was improved by a factor of five or more by the ion implantation. We also investigated the effect on the Zr implantation profile of the multi-component energy distribution of the ion beam.

Nanophase formation and its behavior of corrosion resistance in C+Ti dual implanted steel

After corrosion and pitting corrosion, the wire nanometer phases are observed using a transmission electron microscope (TEM) in C+Ti dual implanted H13 steel. The property of corrosion resistance dual-implanted (C+Ti) H13 steel is studied using multi-sweep cyclic voltammetry. TEM images of the cross section of an implanted sample reveal plenty of circular nanometer structures with diameters of 10–30 nm. The phases are densely embedded in the implanted layer. The embedded structure improves the surface corrosion resistance, as can be observed with a scanning electron microscope (SEM). The phases with the shape of a tiny wire in nanometer size are formed. The nanometer phases, consisting of TiC, FeTi and FeTi2, are formed in dual implanted layer. The corrosion current peak density decreases to 1/16–1/10 that of the unimplanted H13 steel. The formation conditions of the nanometer phases and their effects are investigated. The passivation layer consists of nanometer phases. The corrosion resistance of the dual implantation can be further enhanced with an increase in ion dose.

Corrosion behavior of the embedded layer with nanometer phase in Ti and Ti+C-implanted steel

Ti and Ti + C ions were implanted into H13 steel, the cross-sections of the samples were observed by transmission electron microscope (TEM). The results show that the structure of the implanted layer has greatly changed. The layer, embedded with nanometer phase of FeTi 2, TiC and Fe–C compound, is formed in Ti and Ti + C ion-implanted layer. The thickness of the embedded layer is greater than that of the corresponding ion range. The structure of the double ion-implanted layers is obviously different. The wear resistance and hardness of Ti or Ti + C-implanted H13 steel increased, and the friction coefficient decreased. This indicates that unique resistance for wear and corrosion can be obtained. An even higher corrosion resistance has been found, as the layer with an embedded structure was formed in Ti or Ti + C-implanted H13 steel. The results of electrochemical measurement show that the corrosion current density decreases obviously with increase of ion dose. The corrosion current density of Ti-implanted steel with a dose 1.3×10 18 cm −2 is 5–13% of that of unimplanted steel. The corrosion behavior of Ti + C dual implantation could be further improved; the corrosion current density is 1.2% of that of non-implanted samples. The corrosion trace could not be observed on the annealing sample by scanning electron microscope (SEM), after multi-sweep cyclic voltammetry (CV) of 40 cycles were performed on it. Finally, the modification mechanism of Ti or Ti + C-implanted H13 steel is discussed.

Behaviour of MEVVA metal ion implantation for surface modification of materials

MEVVA ion implantation of Mo, Mo + C and Ti + C in H13 steel at high ion flux was studied. The results show that dispersive hardening phases grow with increasing ion flux. The growth of the phases is accelerated by annealing. The resistance to wear and corrosion for Mo-implanted steel is improved relative to unimplanted steel. After corrosion, the dispersive hardening phases which inhibit corrosion can be observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A dense network of phases for Mo + C-implanted steel is observed by SEM and TEM. The corrosion resistance of Mo + C-implanted H13 steel is much better than that of Mo-implanted H13 steel. The corrosion current density for Ti + C-implanted H13 steel is very small (0.1 mA cm −2); after annealing, the current density is near zero. SEM observation shows that, after corrosion for 50 voltage loops, no corrosion trace can be observed.

A study of pulsed high flux Ti, Mo, V and Y ion implantation for surface modification of resistances in wear, corrosion and oxidation

The resistances to wear, corrosion and oxidation of implanted H13 steel using pulsed Ti and Y ions were studied. The Ti and Y ions were produced from a metal vapor vacuum source (MEVVA). The instantaneous beam current was from 0.3 to 1 A and energy was from 25–50 keV. The target temperature was raised to 300°C for a flux of 38 μA cm −2 and to 600°C for a flux of 76 μA cm −2. The hardness of Ti-implanted steel increases with ion dose and decreases with ion flux. The wear resistance of Ti-implanted steel is 3–3.7 times that for the unimplanted steel. Precipitates of Fe 2Ti were observed by X-ray diffraction and high energy electron microscopy (HVEM). The size and amount of Fe 2Ti increases with increasing ion dose and ion flux. The oxidation barrier of Y-implanted H13 steel formed during oxidation at 800°C for 10 min was measured by RBS. The oxidation rate of Y-implanted steel was 8–10 times less than the unimplanted steel. The electrochemical properties of Ti and Y implanted steel in 1 mol H 2SO 4 or solution of NaCl were studied. The results show that the Y implantation is effective for improvement of corrosion inhibition of H13 steel, GCr15 and 304 stainless steel.

Corrosion and mechanical behavior of ion implanted bearing steels for improved fretting behavior

Ion implantation of AISI 52100 and 1070 steels was conducted in order to improve the corrosion, wear and ultimately the fretting behavior of the steels. Implantations consisted of 1 × 10 17 Ta + cm -2 , 3 × 10 17 Ti + cm -2 + 1.5 × 10 17 C + cm -2 , and 3.1 × 10 17 Ti + cm -2 + 1.55 × 10 17 N + 2 cm -2 . All implantations were successful in improving the corrosion resistance. On average, the peak anodic current was reduced by over 300 mV, the passivation potential was reduced, and the pitting potential was increased by over 1000 mV in 0.01 M NaCl. Ti + C and Ti + N implantations increased the load-carrying capacity in lubricated scuffing tests by 60% and 40% respectively. Ta produced no improvement in scuffing resistance. Ti + N implantation increased the hardness by 25% over the unimplanted steel and both Ti + C and Ta implantation reduced the surface hardness. Fretting wear was reduced only slightly in the Ta implanted sample and increased in both the Ti + C and Ti + N implanted samples with the latter showing 4–5 times the weight loss as the unimplanted sample. The correlation between fretting and hardness supports a mechanism in which the hard surface layer breaks into fine particles which act as an abrasive under the intense load of the balls.

Surface structure of nitrogen ion-implanted 304 stainless steel

Modification of the structure and the creation of nitrides in the surface layer of 304 stainless steel due to nitrogen ion implantation with doses of 1 × 10 17 , 3 × 10 17 and 5 × 10 17 N cm -2 at an accelerating potential of 90 kV were investigated by X-ray photoelectron spectroscopy combined with argon ion sputter etching. In a thin surface layer of unimplanted steel there is a structure which consists of a chromium enriched oxide layer and an adjacent inner layer enriched by nickel. After the ion implantation, the double-layer surface structure remained, but chromium enrichment was enhanced and the thickness of the chromium-rich oxide layer increased with an increase in the implantation dose. This modification can be explained qualitatively by radiation-enhanced migration of metal atoms to the surface and their oxidation in a sub-surface reaction zone. The creation of Cr 2 N and Fe 4 N in the main area of nitrogen distribution and CrN in the chromium enriched layer near the surface was observed.

Wear properties of metal ion implanted 4140 steel

AISI type 4140 (high tensile) steel has been implanted with tungsten and titanium using a metal vapour vacuum arc ion source. Doses in the range (1–5)× 10 16 ions cm −2 were implanted to a depth of approximately 30 nm. The relative wear resistance between non-implanted and implanted specimens has been estimated using pin-on-disc and abrasive wear tests. Implantation of titanium decreased the area of wear tracks by a factor of 5 over unimplanted steel. In some cases the steel was also hardened by a liquid carburization treatment before implantation. Abrasion tests revealed a further improvement in wear resistance on this material following ion irradiation.

Reduced hydrogen embrittlement susceptibility in platinum implanted high strength steel

High strength steels suffer from a high susceptibility to hydrogen embrittlement in a corrosive atmosphere, a factor which limits their usefulness. A good catalyst, such as platinum, present on the surface of the steel may lead to a low value of hydrogen overvoltage, thereby reducing the accumulation and subsequent diffusion of atomic hydrogen into the metal. In the present study, platinum was implanted into high strength electroslag remelted (ESR) 4340 steel specimens to a dose of 10 16 atoms/cm 2. Both Pt-implanted and unimplanted specimens were rate charged with hydrogen. The relative concentration of diffusible hydrogen was determined using an electrochemical measurement device known as a Barnacle Electrode. The specimens implanted with platinum exhibited less diffusible hydrogen than the unimplanted steel. Slow strain rate notched-tensile tests, in an aqueous solution of 3.5 wt.% NaCI, were performed in order to evaluate the effect of hydrogen on strength and ductility. The Pt-implanted specimens were able to sustain significantly higher loads before fracture than their unimplanted counterparts. Scanning electron microscopy (SEM) verified the presence of brittle cracking typical of hydrogen embrittlement type failures. Degradation of mechanical properties due to hydrogen embrittlement was thus significantly reduced. This suggested that both the electrochemical and catalytic properties of the Pt-implanted surface were responsible for the improvement in properties.

Examination of wear, hardness and friction of nitrogen-, boron-, carbon-, silver-, lead- and tin-implanted steels with different chromium contents

Implantations of nitrogen, boron, carbon, silver, lead and tin in four different steels with chromium contents of 1.5%–18% were performed. The doses applied were between 10 17 and 5 × 10 17 cm −2, the ion energy was 50–100 keV. Wear and friction of the implanted layers were tested using a pin-on-disc oscillating tribometer. Hardness was investigated using a microhardness tester allowing loads down to 0.05 × 10 −2 N. It was found that nitrogen is very effective in hardening steels with a high chromium content (around 18%) and in decreasing the wear rate of up to three orders of magnitude. Microscopic observations of the abraded surfaces show a strong effect of fatigue after tribological stress in the case of unimplanted steels. Implanted surfaces have a smooth abrasive path even after a long period of testing. Boron reduces the wear of hardened X90CrMoV18 by two orders of magnitude. Carbon is very effective in hardening and reducing wear in the low-chromium tool steel 100Cr6 which cannot be hardened by nitrogen implantation. All results strongly depend on atmosphere, load and the ball material in use for friction tests. The implantation of silver, tin and lead does not change the hardness of the steels investigated. However, a reduction of friction was found, thus also reducing the wear rate.

Effects of sulphur ion implantation on the electrochemical behaviour of two stainless steels in sulphuric medium

We have studied the electrochemical behaviour in sulphuric acid of two austenitic stainless steels (AISI 304 L and AISI 321) modified by sulphur ion implantation. Surface analysis of oxygen and sulphur by LEEIXS and XRFS were performed before and after polarization on unimplanted and on implanted samples. I/E curves with implanted steels reveal an important corrosion peak (α peak) recovering widely the active peak of unimplanted samples. For high implanted doses, another peak (β peak) appears in the passive range. High doses implanted steels polarized in the range of the α peak exhibit a sulphur enriched black surface layer. SEM examination of this layer shows it is constituted by flakes rolling up themselves. The formation of a superficial non-protective sulphide layer and the internal stresses of this layer explain the corrosion enhancement of sulphur implanted materials. After dissolution of this layer the behaviour of unimplanted steels is found again.

Fretting wear of nitrogen-implanted AISI 304 stainless steel

Fretting wear resistance of nitrogen-implanted AISI 304 stainless steel was measured and compared to that of unimplanted steel. After 5 × 10 3 cycles, unimplanted steel revealed severe damage on non-slip area and adhesive-type wear on microslip region whereas nitrogen-implanted stainless steel was still undamaged. The improved fretting wear resistance is explained to be due to the increased load carrying capacity and decreased adhesion of nitrogen-implanted steel.