Comparison of tribocorrosion behavior between 304 austenitic and 410 martensitic stainless steels in artificial seawater

Abstract

In order to obtain a comprehensive understanding of the tribocorrosion performance of 304 austenitic and 410 martensitic stainless steels in artificial seawater, systematic tests were carried out in this work. The results from intermittent test revealed that load and sliding speed had great influence on the cathodic shift of OCP caused by sliding wear. Through potentiodynamic and potentiostatic polarization tests, which were performed under cathodic, OCP and anodic potentials, it was confirmed that synergistic effects existed between wear and corrosion and were linked with applied potential. In addition, it was found that tribocorrosion behavior of the two alloys was affected by microstructural characteristics and chemical composition, which were closely related to the mechanical properties and repassivation kinetics of passive film. Particularly, 304SS exhibited a better localized corrosion resistance compared with that of 410SS due to the higher content of chromium and nickel. For both materials, hardness inside the wear track was higher compared with the unworn surface due to a rubbing-induced hardening effect.

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1. Introduction

Tribocorrosion is a type of material degradation resulting from the combined action of mechanical and chemical or electrochemical processes. This phenomenon is encountered in numerous engineering fields, such as mining, food manufacturing, medical implants, marine and offshore applications, where two contacting materials are subjected to sliding or rolling wear in corrosive environment.¹ Hence, for mechanical equipment used in these fields, it is inevitable that wear and corrosion take place simultaneously and interact together, leading to the total material loss significantly exceed the sum of the individual mass loss due to static corrosion and pure mechanical wear.^2,3 As a result, the synergism between wear and corrosion can considerably shorten their service life. Therefore, a deep understanding of the synergism between wear and corrosion is of prime importance in selecting proper materials for the conservation of equipment.

Because of the greatly developed deep-sea and offshore engineering, the importance of seawater, which is an inherently chemical aggressive liquid, has been increasing in the past few decades. Stainless steels are iron-based alloys which are extensively used in engineering applications because of their good corrosion resistance derived from a thin passive film (1–10 nm) formed in various media.^4,5 However, under tribocorrosion condition, tribological contact often causes rupture or removal of the passive oxide film, leaving the underlying bulk metal exposed to the corrosive solution. In order to gain a better insight into the mechanisms of tribocorrosion process, such issues as depassivation and repassivation kinetics should be highlighted.^6,7 It is well known that alloying elements have strong impact on the microstructure of stainless steel, especially metallographic structure, which is closely related to their corrosion susceptibility and mechanical properties. However, different alloying elements can introduce varied changes in the characteristics of stainless steel, suggesting that a compromise between corrosion resistance and mechanical properties always exists.⁸ In accordance with metallic phase, stainless steels can be roughly divided into four categories, namely austenitic, martensitic, ferritic and ferritic–austenitic duplex stainless steel. Austenitic stainless steels possess great uniform corrosion resistance and exhibit faster repassivation kinetics than martensitic grades, but their hardness and wear resistance are inferior. In turn, martensitic stainless steels are sensitive to stress corrosion cracking, showing moderate corrosion resistance while exhibiting high mechanical properties such as strength and hardness which make them prevalent in various tribological applications.⁹ Although both austenitic and martensitic stainless steels have fine resistance to wear and corrosion respectively, it does not mean that they show good resistance to tribocorrosion, because the breakdown of passive film may significantly change their global behavior during tribocorrosion process, e.g., by bringing about pitting corrosion.

So far, very few efforts have been made to compare the tribocorrosion behavior among different grades of stainless steels in artificial seawater. However, the discrepancies between stainless steels have significant influences on the tribocorrosion behavior since the corrosion–wear synergism is sensitive to the microscopic features.^10,11 In this work, tribocorrosion performance of 304 austenitic (γ) and 410 martensitic (α′) stainless steels in artificial seawater were assessed and compared using a pin-on-disc tribometer integrated with an electrochemical workstation, enabling to study the individual effects of wear and corrosion as well as their synergistic contributions to the total material degradation. The objective of this work is to investigate the effect of electrochemical and mechanical parameters (e.g. potential, sliding speed and applied load) on the tribocorrosion behavior of the two types of stainless steels. The results are discussed with respect to the quantification of the synergistic effect between wear and corrosion, providing an approach to sustainable material selection for practical applications.

2. Experimental

2.1. Materials and artificial seawater preparation

Experiments were performed on samples of AISI 304 stainless steel (304SS) and AISI 410 stainless steel (410SS), which were machined into a ring form with outer diameter of 54 mm and inner diameter of 38 mm. To obtain a smooth and uniform surface, specimens were ground with 180, 800 and 1500 grit SiC papers respectively. Afterwards, they were degreased with acetone ultrasonically and subsequently cleaned in water. Non-conducting resin was used to ensure that only the upper surfaces of samples were exposed to air. Counterbody used in this work was inert Al₂O₃ cylindrical pins with nominal dimensions of Φ 4 mm × 13 mm. To improve the reproducibility of the test, artificial seawater other than natural seawater, which varied with sea depth, area and season, was used in this experiment. Artificial seawater was prepared in accordance with ASTM D1141-98, the pH value and chlorinity of which were 8.2 and 19.38, respectively.

2.2. Methods

A tribo-electrochemical test system used in this work is schematically illustrated in Fig. 1, which is assembled by integrating a MMW-1 pin-on-disc tribometer (manufactured by Jinan Shijin Testing Machine Group) with an electrochemical workstation. Electrochemical control of specimens was achieved by a three-electrode system including an Ag/AgCl reference electrode, a counter electrode (a large surface platinum grid) and a working electrode (metal disc samples). All potentials are given here with reference to Ag/AgCl reference electrode. The tribo-electrochemical cell and sample holder were both made of Teflon, an insulating and anti-corrosion material, so as to electrically isolate sample from equipment and avoid electrochemical disturbance to the tribocorrosion tests.

Fig. 1 Schematic diagram of the apparatus used in this work.

The first series of experiments carried out in this study is the intermittent sliding wear tests under open circuit potential (OCP) condition, with sliding speed and normal load being varied and the variation of OCP being monitored. After the immersion of specimens in solution for 1200 s, intermittent sliding was started under the following conditions: the constant load of 40 N at the sliding speed of 40 rpm and 60 rpm, respectively; the constant sliding speed of 80 rpm at the load of 40 N, 60 N and 80 N, respectively. The tests with and without sliding are both performed for 1000 s. The second series of experiments performed in this study is the potentiodynamic polarization tests which involves measuring the polarization curves of samples with sliding (80 N, 80 rpm) and without sliding at sweep rate of 2 mV s⁻¹, from onset potential of −1.0 V to final potential of 0.7 V. Lastly, sliding wear tests (80 N, 80 rpm) were carried out at cathodic, free and anodic potential respectively and the evolution of current transients were measured. Values of applied potentials for two materials are listed in Table 1. All experiments were conducted at room temperature and repeated a minimum of three times for reproducibility.

Table 1 Applied potentials for both materials in potentiostatic tests

		Applied potentials (V/Ag/AgCl)
		Cathodic	Open circuit	Anodic
Material	304SS	−0.7	−0.126	0.1
	410SS	−0.7	−0.187	0.1

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After tests, specimens of 304SS and 410SS were polished and then etched using Carpenter 300 etchant (3 mL HCl, 12 mL H₂O and 1 g FeCl₃) and Kalling' s no. 2 etchant (33 mL HCl, 33 mL CH₃CH₂OH, 33 mL H₂O and 1.5 g CuCl₂), respectively. The microstructural characterizations of etched samples were examined using an Olympus BX53T-12F01 optical microscope. For metallographic analysis, X-ray diffraction (XRD) was performed on a PANalytical Empyrean diffractometer using Cu K_α radiation. Morphologies of worn surfaces and wear debris were studied by a JEM-5600LV scanning electron microscope (SEM). Rockwell hardness (HRB) was measured by a Model HRS-150 Digital Rockwell Hardness Tester with a spherical diamond indenter. The applied load was 100 kg during 5 s. Ten indentations were made for each sample and the average values were taken.

In order to figure out the interactive mechanism in tribocorrosion, an approach is postulated according to ASTM G119-04.

T = C₀ + W₀ + S (1)

where T is the total tribocorrosion loss rate, C₀ is the corrosion loss rate in the absence of wear, W₀ is the wear loss rate in the absence of corrosion, and S is the synergistic effect between wear and corrosion which consists of wear-induced corrosion (ΔC_W) and corrosion-induced wear (ΔW_C), according to eqn (2):

S = ΔC_W + ΔW_C (2)

3. Results and discussion

3.1. Microstructural characterization

Microstructure of the test materials and the corresponding XRD patterns are presented in Fig. 2. And the chemical compositions of the two types of stainless steels are listed in Table 2. For 304SS (Fig. 2a), a typical austenitic structure is obtained. For 410SS (Fig. 2b), most of the structure consist of a phase appeared in the shape of lath, which presents the major martensitic phase. The minor ferrite phase, shown in the higher-magnification embedded image in Fig. 2b, is heavily attacked by etching and appears with average grain size of some tens of micrometers within the martensitic matrix. XRD analysis confirmed the observation about the microstructure of 304SS and 410SS. As can be seen in Fig. 2c, the presence of γ peaks indicates the existence of face centred cubic austenitic phase (PDF 33-0397). It should be emphasized that there is observed a small martensite peak in 304SS, which is induced by polishing treatments. Moreover, the α′ martensite (body centred tetragonal) peaks and δ ferrite (body centred cubic) peaks are presented in Fig. 2d for 410SS.

Fig. 2 Optical microstructure of (a) 304SS and (b) 410SS and XRD patterns of (c) 304SS and (d) 410SS used in tribocorrosion tests.

Table 2 Chemical composition of alloys used in the tribocorrosion experiments

Material	Chemical composition (wt%)
	C	Si	Mn	P	S	Cr	Ni	Fe
304SS	0.05	0.59	0.88	0.015	0.028	18.5	8.12	Bal.
410SS	0.045	0.45	0.50	0.020	0.001	13.0	0.43	Bal.

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3.2. Tribo-electrochemical behavior

3.2.1. Influence of sliding speed and applied load on open circuit potential. The OCP of 304SS and 410SS recorded as a function of time during intermittent sliding are shown in Fig. 3. From Fig. 3a, it can be clearly seen that during the initial stage of immersion, the OCP of 304SS increases gradually with time, probably due to the thickening of the passive film. Nevertheless the following slow decrease is because of the electrochemical destabilization of the passive film by chloride ions.^12,13 At a specific applied load and sliding speed, the OCP shifts abruptly to more negative direction with the onset of sliding, although there are some differences in the extent of the shift. This cathodic shift of OCP is due to the rupture or removal of the passive film followed by the exposure of the fresh metal surface, which increases the anodic reaction and the surrounding areas are cathodically polarized by the released electrons.¹⁴ It can be detected that the magnitude of the cathodic shift of OCP increases with increasing sliding speed and increasing applied load. The increasing sliding speed causes increased contact frequency and less enough time for the repassivation of wear track areas, as well the increasing applied load accelerates the ratio of worn to unworn areas, thus leading to the decrease of OCP. Then, a stable state of OCP is reached due to the establishment of equilibrium between the electrochemical repassivation and mechanical depassivation rate. When sliding is ceased, the OCP of 304SS increases sharply at first several seconds and during the off time it gradually reaches the initial level resulting from the repassivation of the passive film.

Fig. 3 The evolution of open circuit potential of (a) 304SS and (b) 410SS as a function of time during intermittent sliding under varied sliding speed and applied load.

As can be seen from Fig. 3b, the evolution of OCP of 410SS during intermittent sliding reveals some differences compared with 304SS. At the load of 40 N, the cathodic shift of OCP almost have no significant change with the increase in sliding speed from 40 rpm to 80 rpm. It is generally accepted that the instantaneous value of OCP not only depends on the ratio between passive and depassivated areas, but also depends on the thickness of passive film in these areas. Although both of sliding speed and load can affect these influencing factors, the degree of impact on the value of OCP strongly depends on the material itself. For 410SS, during the intermittent tribocorrosion test, sliding speed has little effect on the corrosion susceptibility, while applied load has great influence on it. As load increases from 40 N to 60 N, the OCP of 410SS negatively shift about 0.25 V, suggesting the more vulnerable to corrosion under sliding condition due to the establishment of galvanic coupling between the mechanically depassivated surfaces (anode) and surrounding passive surfaces (cathode).¹⁵ Moreover, the heavier the applied load during sliding, the greater the corrosion susceptibility of 410SS in artificial seawater. As shown in Fig. 3b, a sharp increase in potential takes place after the cathodic shift occurs at the load of 60 N and sliding speed of 80 rpm. This is attributed to a running-in period, normally referring to the changes in friction which occurs before the tribo-system reaches steady state after start-up. During the running-in stage, the OCP decreases further owing to an abrupt increase in the depassivated areas. A steady state friction then follows when the active area is constant and the corresponding increased OCP value also achieves stable. In addition, applied load has a significant impact on the running-in period. That is, the higher load can induce a longer and more severe running-in stage, resulting in the accelerated wear. In this test, the running-in stage is negligible at the applied load of 40 N, indicating that the abrasion between 410SS and Al₂O₃ is relatively mild at the initial contact under this condition. When sliding is terminated, OCP value of 410SS cannot return back to the initial value indicating the incomplete repassivation of the passive film on surface. Such a performance reveals that 410SS have much worse repassivation ability than 304SS, making a result of the poor durability in practical applications where tribocorrosion is prevailing.

3.2.2. Potentiodynamic polarization behavior. The potentiodynamic polarization curves obtained from 304SS and 410SS with and without sliding in artificial seawater are shown in Fig. 4a and c. It is observed that the corrosion potential (E_corr) of 410SS is more negative than that of 304SS under both of static corrosion and tribocorrosion conditions, implying that 410SS are more susceptible to corrosion in artificial seawater. From a componential point of view, this is due to the high concentration of nickel and chromium in 304SS compared to 410SS (Table 2).¹⁶ With the onset of sliding, the E_corr shifts cathodically and the anodic current increases by almost two orders of magnitude in 304SS and three orders of magnitude in 410SS. However, in the case of 410SS, the difference of anodic current between static corrosion and tribocorrosion is diminished in the transpassive region. This higher passive current density demonstrates poorer passive film stability of 410SS than 304SS. Moreover, the fluctuations of polarization curves noticed under tribocorrosion condition are mainly attributed to the passivation–activation transitions taking place in the wear track.^17,18 Under static condition, the pitting potential (E_pit) of 304SS (0.5336 V) is higher than that of 410SS (0.2135 V) and 304SS shows a wider passive region. Thus, the localized corrosion resistance of 304SS is superior to 410SS in artificial seawater.

Fig. 4 Potentiodynamic polarization curves of (a) 304SS and (c) 410SS under sliding and without sliding in artificial seawater. Current density of (b) 304SS and (d) 410SS varied over time at anodic, open circuit and cathodic potentials, respectively.

During sliding friction process in tribocorrosion system, the changes of current density with different applied potentials can be used to reflect the interaction between wear and corrosion, and such changes are studied in this work as shown in Fig. 4b and d. At applied cathodic potential of −0.7 V, current density for both 304SS and 410SS remains negative before, during and after sliding, indicating that the dissolution of material by corrosion attack can be negligible and material degradation mainly caused by mechanical wear. As applied potential increases to OCP, a sharp increase in current density can be observed with the onset of rubbing due to the abrasion of the passive film and then the anodic dissolution of the material inside the wear track, confirming accelerated wear-induced corrosion. After sliding is stopped, current density decreases immediately, indicating that corrosion is alleviated as soon as rubbing is stopped. However, as the onset of anodic potential of 0.1 V, current density of 410SS rises modestly after the sharp fall, which is attributed to the pitting corrosion in wear track. When friction is stopped, the passive film cannot be repassivated completely, some uncovered bare surface within wear track will still suffer from pitting corrosion since the applied potential (0.1 V) is more noble than the pitting potential (−0.0563 V) of the bare metal of 410SS. Thus, a pickup of the current density for 410SS occurs. Moreover, the current density of 410SS is higher than that of 304SS at applied free and anodic potential, indicating that the passive film formers, especially chromium and nickel which are rich in 304SS as compared to 410SS, can act as a barrier layer to diminish the dissolution of material.

3.3. Friction and wear behavior

3.3.1. Tribocorrosion rate. In Fig. 5, the total mass loss and average friction coefficient are plotted against applied potential for 304SS and 410SS, respectively. Clearly, applied potential has a significant influence on the average friction coefficient and material loss for the two types of alloys. As shown in Fig. 5a, the total mass loss of 304SS increases remarkably with increase in applied potential, indicating that in the presence of corrosion, either at OCP or at anodic potential, there is a synergism between wear and corrosion leading to accelerated material degradation. Nevertheless, the maximum of the total mass loss of 410SS is observed at applied free potential rather than anodic potential. This result implies that anodic potential brings about lubricating effect within wear tracks in agreement with the results obtained by other investigators.^19,20 It is also evident that material loss of 410SS is greater than 304SS except the condition at the highest potential. This behavior is expected to correlate with the different microstructure of the two tested metals. Indeed, 410SS possess a heterogeneous structure, which results in the non-uniform deformation of metal under sliding motion and the formation of micro-galvanic couples.^21–23 Once micro-galvanic corrosion takes place, the synergistic effects are accelerated leading to more severe damage of the material.²⁴ Moreover, in the case of 304SS, it exhibits faster repassivation rate since the higher chromium and nickel content. Hence, the material loss is more severe of 410SS than that of 304SS at OCP and applied cathodic potential.

Fig. 5 Total mass loss (a) and average friction coefficient (b) of 304SS and 410SS as a function of applied cathodic potential (A), OCP (B) and anodic potential (C), respectively.

The variation tendency of average friction coefficient is similar to that of material loss with the change of applied potential for both 304SS and 410SS, as shown in Fig. 5b. Due to increased roughness of the surface of wear track caused by corrosion, either at OCP or at applied anodic potential, the friction coefficient of 304SS is increased. Moreover, at OCP and applied cathodic potential, the friction coefficient of 304SS is lower than that of 410SS whereas it is reversed at anodic potential. The variation is due to the formation of pits inside the wear track for 410SS at anodic potential, which will decrease the real contact area between the two mated materials and further cause reduced friction because of reduced adhesive junction shearing.²⁵

3.3.2. Hardening effect. As shown in Table 3, the Rockwell hardness values taken from wear track and unworn surface indicate that there is a work-hardening effect on 304SS and 410SS. For both 304SS and 410SS, within wear tracks, the hardness values observed in cathodic polarization test are higher than those observed in OCP and anodic polarization tests. However, applied potential has no prominent effect on the hardness of unworn surfaces. Moreover, the hardness values inside the wear track are higher than those in unworn surface. As demonstrated, polarization at the cathodic potential will lead to hydrogen intake by the penetration of hydrogen atoms into alloy and consequently material hardening and hydrogen embrittlement take place.²⁶ Compared with unworn surface, the hydrogen intake is larger in wear track because the increased dislocations caused by wear which can act as trapping sites for hydrogen atoms. Hence, the maximum hardness values are observed in the wear track at cathodic polarization tests.

Table 3 Rockwell hardness values of wear track and unworn surface of materials tested at applied cathodic, OCP and anodic potential

Material	Wear track			Unworn surface
	Cathodic potential	OCP	Anodic potential	Cathodic potential	OCP	Anodic potential
304SS	84.2	82.7	80.4	79.1	78.9	79.2
410SS	89.6	87.1	85.4	85.0	84.9	84.8

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3.3.3. Worn surface and wear debris. In order to have a deep understanding of the wear mechanism of 304SS, the worn surface, wear debris and transfer film formed on alumina pin after tribocorrosion at applied cathodic, OCP and anodic potentials were examined. As shown in Fig. 6, many grooves are observed on the worn surface which is caused by the asperities of harder Al₂O₃ counterface, indicating that abrasive wear is the principal wear mechanism.²⁷ And, the higher the applied potential, the more severe the abrasive wear. This is linked with that wear track is roughened by corrosion which becomes more intensive with the increase in potential, leading to the acceleration of abrasive wear. The wear debris morphology in Fig. 6, which is characterized by machining chips, is in agreement with the abrasive wear mode of 304SS. In addition, laminar tearing and residual margins also appear on the worn surface. Coinciding with the flaky-like wear debris with different sizes, it is clear that delamination wear is another primary wear mechanism for 304SS. Meanwhile, it can be seen that Al₂O₃ counterpart is patched with transferred material. The material transfer on the counterpart is composed of many small clumps gathered during continuous sliding friction, which is sheared from 304SS by the asperities of harder Al₂O₃.²⁸

Fig. 6 Typical morphology of worn surface, wear debris and transfer film formed on alumina pin for 304SS after tribocorrosion at applied cathodic, OCP and anodic potentials in artificial seawater.

The morphology of worn surface, wear debris and transfer film formed on alumina pin for 410SS after tribocorrosion at tested potentials are presented in Fig. 7. Similar to 304SS, the wear track is also characterized by grooves, consistent with machining chips observed in wear debris after tribocorrosion. Again, abrasive wear is the main wear mechanism of 410SS. When the Al₂O₃ counterface morphologies of the two alloys are compared, it may be noticed that, the transfer material on Al₂O₃ counterface mated with 410SS is abundant and almost intact on the contact surface, indicating that adhesive wear is another wear mechanism of 410SS. Moreover, there are some areas on the worn surface of 410SS show torn and fibrous features, which is also the evidence of adhesive wear.²⁹ As confirmed by the morphology of worn surface shown in Fig. 7, a few small pits occur inside the wear track of 410SS at applied anodic potential; while no pits are observed for 304SS at same condition, manifesting that 410SS is more prone to pitting corrosion.

Fig. 7 Typical morphology of worn surface, wear debris and transfer film formed on alumina pin for 410SS after tribocorrosion at applied cathodic, OCP and anodic potentials in artificial seawater.

3.4. Synergistic effect between wear and corrosion

Based on the presented electrochemical results, it is clear that synergistic effect exists between wear and corrosion which results in wear-induced corrosion and corrosion-induced wear. Fig. 8 shows the contribution of W₀, C₀, ΔC_W and ΔW_C to the total material loss of 304SS and 410SS at different applied potentials. It can be seen that pure mechanical wear (W₀) is pronounced at any potential for both of the two metals and it is higher for 410SS than 304SS, which can be explained by the heterogeneous microstructure of 410SS, leading to non-uniform deformation when the passive film is removed by sliding friction. Moreover, the material loss due to pure corrosion (C₀) is almost negligible, although for 410SS, its importance grows markedly with increase in potential. It is also emphasized that the wear–corrosion synergism including ΔW_C and ΔC_W plays an important role in material degradation. Hence, material degradation is mainly caused by pure mechanical wear and synergism action between wear and corrosion for the two type alloys. In the case of 304SS, the synergistic effect is dominated by ΔW_C which increase significantly with increase in potential. For 410SS, the synergistic effect is dominated by ΔW_C at OCP, whereas the synergistic effect is primarily ΔC_W at anodic potential. Actually, the relative contributions of ΔW_C and ΔC_W to the material loss for stainless steels in tribocorrosion process have been studied by several investigators. Sun et al. found that the relative dominance of ΔW_C and ΔC_W for AISI 304 stainless steel in 0.5 M NaCl solution is controlled by corrosion type within the wear track.³⁰ Because corrosion pits can promote crack initiation and propagation leading to accelerated wear, ΔC_W is dominant when pitting corrosion takes place inside the wear track. On the contrary, ΔW_C becomes more dominant when general corrosion only occurs inside the wear track. Zhang et al. studied the corrosion wear rates of 304SS in 3.5% NaCl solution and found that ΔW_C is the main cause of the material degradation in the test conditions.³¹

Fig. 8 Contribution of W₀, C₀, ΔC_W and ΔW_C to the total material loss at applied cathodic (A), OCP (B) and anodic (C) potential.

4. Conclusions

In this paper, tribocorrosion behavior of 304 austenitic and 410 martensitic stainless steels have been investigated in artificial seawater. Based on the presented results, following conclusions can be drawn:

(1) In the intermittent tests, cathodic shift of OCP is observed in both materials, confirming that corrosion susceptibility increases once the passive film is damaged by rubbing. Moreover, the degree of such cathodic shift increases with the increase in applied load and sliding speed.

(2) Potentiostatic sliding wear tests of the materials are conducted at applied cathodic, OCP and anodic potentials and the results reveal that current density increase sharply due to the depassivation of passive film resulting from rubbing. Also the corrosion current density of 410SS is higher than that of 304SS.

(3) During tribocorrosion process, corrosion attack within wear track is more severe for 410SS. This is due to poorer repassivation ability of martensitic stainless steel than that of austenitic stainless steel. In addition, compared to type 304SS, the occurrence of pitting corrosion is easier for 410SS under tribocorrosion.

(4) There is a general trend that the total material loss increases with the increase in applied potential, although the mass loss decreases for 410SS at anodic potential, which is probably due to a lubricating effect of the formed oxide products.

(5) For 304SS, the main wear mechanisms are abrasion and delamination; whereas the wear mechanisms are adhesion and abrasion in the case of 410SS.

Acknowledgements

The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China (Grant No. 51405478) and the National Basic Research Program of China (973 Program, Grant No. 2014CB643302).

References

1. Q. Bi, W. Liu, J. Ma, J. Yang, Y. Pu and Q. Xue, Tribol. Int., 2009, 42, 1081–1087.
2. R. C. C. Silva, R. P. Nogueira and I. N. Bastos, Electrochim. Acta, 2011, 56, 8839–8845.
3. Y. Sun, X. Li and T. Bell, Surf. Eng., 2013, 15, 49–54.
4. B. S. Sazzad, M. A. Fazal, A. S. M. A. Haseeb and H. H. Masjuki, RSC Adv., 2016, 6, 60244–60263.
5. A. Stachowiak and W. Zwierzycki, Tribol. Int., 2011, 44, 1216–1224.
6. J. X. Li, W. Y. Chu, Y. B. Wang and L. J. Qiao, Corros. Sci., 2003, 45, 1355–1365.
7. Y. Sun, J. Mater. Process. Technol., 2005, 168, 189–194.
8. K. C. Tekin and U. Malayoglu, Tribol. Lett., 2009, 37, 563–572.
9. E. Huttunen-Saarivirta, L. Kilpi, T. J. Hakala, L. Carpen and H. Ronkainen, Tribol. Int., 2016, 95, 358–371.
10. M. Azzi and J. A. Szpunar, Biomol. Eng., 2007, 24, 443–446.
11. N. Diomidis, J. P. Celis, P. Ponthiaux and F. Wenger, Wear, 2010, 269, 93–103.
12. A. Butt, N. B. Lucchiari, D. Royhman, M. J. Runa, M. T. Mathew, C. Sukotjo and C. G. Takoudis, Journal of Bio-and Tribo-Corrosion, 2014, 1, 4–18.
13. M. Salasi, G. Stachowiak and G. Stachowiak, Corros. Sci., 2015, 98, 20–32.
14. N. Diomidis, N. Göçkan, P. Ponthiaux, F. Wenger and J. P. Celis, Intermetallics, 2009, 17, 930–937.
15. F. B. Saada, Z. Antar, K. Elleuch and P. Ponthiaux, Wear, 2015, 328–329, 509–517.
16. E. Cakmak, K. C. Tekin and U. Malayoglu, Tribology, 2013, 4, 8–14.
17. O. Belahssen, A. Chala, H. Ben Temam and S. Benramache, RSC Adv., 2014, 4, 52951–52958.
18. E. E. Oguzie, Y. Li, S. G. Wang and F. Wang, RSC Adv., 2011, 1, 866.
19. S. Mischler, Tribol. Int., 2008, 41, 573–583.
20. B. A. Obadele, A. Andrews, M. B. Shongwe and P. A. Olubambi, Mater. Chem. Phys., 2016, 171, 239–246.
21. P. Corengia, G. Ybarra, C. Moina, A. Cabo and E. Broitman, Surf. Coat. Technol., 2004, 187, 63–69.
22. D. López, J. P. Congote, J. R. Cano, A. Toro and A. P. Tschiptschin, Wear, 2005, 259, 118–124.
23. R. Puli and G. D. Janaki Ram, Surf. Coat. Technol., 2012, 209, 1–7.
24. F. Ansari, R. Naderi and C. Dehghanian, RSC Adv., 2015, 5, 706–716.
25. J. Soltis, Corros. Sci., 2015, 90, 5–22.
26. M. Favero, P. Stadelmann and S. Mischler, J. Phys. D: Appl. Phys., 2006, 39, 3175–3183.
27. R. Priya, C. Mallika and U. K. Mudali, Wear, 2014, 310, 90–100.
28. M. Scherge, D. Shakhvorostov and K. Pöhlmann, Wear, 2003, 255, 395–400.
29. Y. Sun and E. Haruman, Surf. Coat. Technol., 2011, 205, 4280–4290.
30. Y. Sun and V. Rana, Mater. Chem. Phys., 2011, 129, 138–147.
31. T. Zhang, X. Jiang, S. Li and X. Lu, Corros. Sci., 1994, 36, 1953–1962.

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