The effect of wear and corrosion on internal crystalline texture of carbon steel and stainless steel

The effect of wear and corrosion on internal crystalline texture of carbon steel and stainless steel

Wear 259 (2005) 400–404 The effect of wear and corrosion on internal crystalline texture of carbon steel and stainless steel M.R. Bateni a,∗ , J.A. S...

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Wear 259 (2005) 400–404

The effect of wear and corrosion on internal crystalline texture of carbon steel and stainless steel M.R. Bateni a,∗ , J.A. Szpunar a , X. Wang b,1 , D.Y. Li b,1 a

b

Department of Mining, Metals and Materials Engineering, McGill University, M.H. Wong Building, 3610 University, Montreal, Que., Canada H3A 2B2 Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alta., Canada T6G 2G6 Received 2 August 2004; received in revised form 19 January 2005; accepted 1 February 2005 Available online 10 May 2005

Abstract Wear and corrosion wear involve mechanical and chemical mechanisms and the combination of these mechanisms often results in significant mutual effects. In this research, wear performances, and texture changes of carbon steel AISI 1045 and stainless steel AISI 304 under simultaneous wear and corrosion were investigated and the results were compared with those obtained from dry wear tests. 3.5 wt.% NaCl solution was used as the corrosion agent and a pin-on-disk tribometer was employed to perform wear and corrosion wear tests. Wear tests of carbon steel and stainless steel samples have shown smaller weight losses and lower friction coefficients in the presence of corrosive environment. Texture investigations of the worn samples have shown texture changes after wear and corrosive wear tests. In worn carbon steel samples after dry wear test 0 1 1) 1 0 0 Goss texture and {1 1 1} gamma fiber component were developed in initially random oriented samples, whereas under corrosive wear conditions, {1 1 1}  0 1 1  fiber texture and {0 0 1}  1 1 0  cube texture were obtained. In stainless steel samples, {1 1 2}  1 1 0  texture component were observed under both dry and corrosive wear conditions, in initially random samples. © 2005 Elsevier B.V. All rights reserved. Keywords: Wear; Corrosion wear; Friction; Texture

1. Introduction Considerable plastic deformation, which is produced by frictional forces in the surface layers of metallic objects, causes a preferred orientation of the crystallites in a particular direction and therefore an alteration of the friction and wear behavior of the system [1]. It was reported that there is extensive plastic deformation below the sliding interface, even after a very short sliding time and distance [2]. During sliding under load, whenever shear, tensile, compressive, and thermal stresses exceed the grain boundary strength, failure of the boundary occurs resulting in wear ∗

Corresponding author. Tel.: +1 514 398 4755; fax: +1 514 398 4492. E-mail addresses: reza [email protected] (M.R. Bateni), [email protected] (J.A. Szpunar), [email protected] (X. Wang), [email protected] (D.Y. Li). 1 Tel.: +1 780 492 6750; fax: +1 780 492 2881. 0043-1648/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.wear.2005.02.009

transition to severe fracture. A transition in wear mechanism is a function of normal load, sliding speed, sliding time, temperature, relative humidity and grain size [3]. Texture, internal crystalline structure texture, is one of the fundamental structural parameters in all polycrystalline materials. Texture is formed and transformed by different solid-state processes, such as plastic deformation, crystallization, re-crystallization, grain growth, and phase transformation [4–6]. The future development of new materials with more sophisticated crystal structures will mean that texture measurements will become increasingly important [4]. The mechanical processing of metal surfaces results most frequently in the development of texture in the superficial layer of material. The preferred orientation depends greatly on the method of mechanical finishing. Even if a surface exhibit random texture prior to their use in lubrication systems, sliding, rubbing and or rolling process which is involved in these systems, may give rise to the development of

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surface textures [7]. Tribological behavior during the forming of sheet metals is strongly influenced by the presence of texture [8]. It was reported that sliding creates well-defined textures, with close-packed planes parallel or nearly parallel to the sliding interface [2]. The properties of the material adjacent to the contact area have an effect on the friction and wear behavior of the pair of materials in contact. The contact stresses in technical systems produce plastic deformation in the material close to the surface, which results in the so-called frictional texture [1,9]. Friction forces in the surfaces of the triboelements of a tribological system lead to the formation of characteristic surface textures [10]. Crystallographic re-orientation below a contact surface may be a possible cause for the reduction in the coefficient of friction during sliding wear. Crystallographic re-orientation can produce a reduction in the effective shear stress in near surface regions and a reduction in the required friction force to maintain relative motion. The length of time the material needs to be exposed to stress in order to reach the final state of the frictional texture depends on materials and tribological characterization of the system [1]. The most frequently used and the most complete way of representing texture is the orientation density space called the orientation distribution function, ODF, which is obtained after suitable mathematical transformation from several pole figures.

2. Experimental details Medium carbon steel AISI 1045 and stainless steel AISI 304 samples were used as the experimental materials. A pinon-disk tribometer was employed to evaluate tribological behaviour of samples. Wear tests were conducted at room temperature under dry and corrosive conditions. The corrosive wear behavior of carbon steel and stainless steel samples were studied in 3.5 wt.% NaCl solution. AISI 3Cr12 stainless steel was employed as the counter face. Wear and corrosive wear tests were carried out under different loads of 9.6, 32, 54 and 71 N. For all experiments the sliding distance of 160 m was used. Worn surfaces were then examined with X-ray analysis to determine the presence of preferred orientation. Texture of carbon steel and stainless steel samples after corrosion and corrosive wear test were measured using a D-500 Siemens Xray Goniometer. In order to calculate orientation distribution function (ODF), pole figure data were calculated by Textool software, version 3.2, developed by Resmet Corporation.

3. Results and discussion 3.1. Tribological behavior Wear performances of carbon steel and stainless steel samples during both dry sliding and corrosive wear in NaCl solu-

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Fig. 1. Weight losses of the samples under dry wear and corrosive wear: (a) 1045 carbon steel; (b) 304 stainless steel.

tion were evaluated. Fig. 1 illustrates weight losses of carbon steel and stainless steel samples under different conditions. As the load is increased, the weight loss is increased. It is observed that under corrosive wear condition, weight loss is smaller than dry wear. The dilute NaCl solution was not very corrosive and therefore did not result in severe synergistic attack of wear and corrosion. On the other hand, the NaCl solution reduced the friction between the substrate and the counter face, which consequently decreased the wearing force, thus leading to less damage to the substrate. Variation of friction coefficient in carbon steel and stainless steel samples at a load of 9.6 N are shown in Figs. 2 and 3. It is observed that the coefficient of friction of carbon steel sample is decreased under corrosive environment (Fig. 2). The corrosive solution reduced the friction between the substrate and the counter face, which consequently decreased the coefficient of friction. On the other hand, in the presence of NaCl solution, the formation of surface oxide layer was accelerated. Such an oxide film acts as intermediate layer on the surface, which can reduce the coefficient of friction [11,12]. The ease of formation of the surface oxide layer and decreasing metallic contact between substrate and counter face are main reasons for reducing the coefficient of friction in the presence of corrosive environment. The NaCl solution reduced the adhesion and friction between the substrate and the counter-face, which consequently decreased the wearing force, thus leading to less fluctuation in friction coefficient. Higher coefficient of friction values in stainless steel samples are due to stronger adhesion bonds (Fig. 3). A remarkable stick-slip behavior in friction coefficient of stainless steel samples under dry wear and corrosive wear conditions is observed (Fig. 3). When two surfaces contacted each other, the

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Fig. 2. Variation of friction coefficient in carbon steel sample: (a) dry condition; (b) corrosive condition.

adhesion took place at the contact area and caused stick to take place. The friction force and, consequently, the friction coefficient rose sharply. At some points the tangential force was sufficient to overcome the adhesive bonds at the interface, fracture accrued, and the friction force dropped sharply [13]. 3.2. Texture analysis of worn surfaces Texture data used in the studying of worn surfaces was calculated in the form of pole figures and crystallite orientation distribution functions. ODF of carbon steel sample before

wear and corrosive wear showed initially randomly oriented grains (Fig. 4). After dry wear test, ODF shows the presence of {0 1 1}  1 0 0  Goss texture and {0 1 1}  2 1 1  brass component (Fig. 5). By increasing the applied load to 54 N, the presence of both {0 1 1}  1 0 0 Goss texture, {0 1 1}  2 1 1  brass component, and {1 1 1}  0 1 1  gamma fiber are obvious in the ODF (Fig. 6). During sliding wear, shear and normal loads are created in the contact area. The presence of shear stresses in the interface, caused shear texture of the near surface layers, which consequently caused {0 1 1}  1 0 0  Goss and {0 1 1}  2 1 1  brass texture

Fig. 3. Variation of friction coefficient in stainless steel sample: (a) dry condition; (b) corrosive condition.

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Fig. 4. Orientation distribution function of carbon steel sample before wear test.

Fig. 5. Orientation distribution function of carbon steel sample after dry wear test, under 9.6 N load.

components in carbon steel samples under dry wear tests (Figs. 5 and 6). The formation of {0 1 1}  1 0 0  Goss texture and {0 1 1}  2 1 1 brass texture are characteristic of bcc materials in the presence of shear texture [14,15]. ODF also shows {1 1 1}  0 1 1  gamma fiber under higher loads (Fig. 6). The observation of {1 1 1}  0 1 1  gamma

Fig. 6. Orientation distribution function of carbon steel sample after dry wear test, under 54 N load.

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Fig. 7. Orientation distribution function of carbon steel sample after corrosive wear test, under 9.6 N load.

fiber could be due to plane strain deformation state during dry wear test and under higher loads [14,15]. On the other hand, Goss component could rotate during wear, as in rolling process, into {1 1 1}  1 1 0 components [16]. By increasing the applied load to 54 N, the frictional forces between the counter face and the substrate increased, which subsequently increased the shear stresses between two surfaces. In bcc materials shear stresses are one of the main cause of formation Goss texture [14,15]. As the applied load increased to 54 N, a steady state texture was achieved and further increasing the applied load did not have any effect on the observed texture. Under corrosive wear environment, significant changes in ODF are observed (Fig. 7). The presence of {1 1 1}  0 1 1  fiber texture and {0 0 1)  1 1 0  cube texture are obvious in ODF. In the presence of corrosive environment, NaCl solution acted as a lubricant and metallic contact was minimized. In addition, friction forces in the contact area decreased, which reduced the shear forces. The reduction of shear stresses in the contact area reduced shear texture in the contact area. The absence of shear stresses in the contact area, is the main reason for not observation of Goss and brass texture under corrosion wear condition. The ODF of stainless steel sample shows initially a randomly oriented surface layers (Fig. 8). The presence of {1 1 2}  1 1 0  texture observed after wear test. By increasing the applied load the intensity of {1 1 2}  1 1 0  component was increased (Fig. 9). Although, new texture component weren’t observed as the applied load was increased, but as the applied load was increased, a steady state texture was achieved. The observation of {1 1 2}  1 1 0  components is due to friction force and shear stresses in the interface layer. Under conditions of high contact friction, surface layers of the metal correspond to the stress–strain state of ordinary shear. The acting glide planes should coincide with the shear plane, and the acting slip directions should coincide with the shear directin. Under these conditions {1 1 2}  1 1 0  component is one of the main texture components in

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Goss and brass texture component. The formation of {1 1 1}  0 0 1  gamma fiber components could be due to plane-strain deformation state during dry wear test. 4. In stainless steel samples, under both dry wear test and corrosion wear conditions, {1 1 2}  1 1 0  texture was observed. The observation of {1 1 2}  1 1 0  component is due to presence of shear stresses in the interface.

Acknowledgement The authors acknowledge the financial support from the Natural Science and Engineering Research Council of Canada (NSERC). Fig. 8. Orientation distribution function of carbon steel sample before wear test.

References

Fig. 9. Orientation distribution function of stainless steel sample after corrosion-wear test, 54 N load.

the surface regions {1 1 2}  1 1 0  components are characteristic of shear stress states in fcc metals and alloys [14,17]. The presence of corrosive environment didn’t have any effect on texture components of the system and shear stress still was the predominant deformation state in this system.

4. Conclusions 1. The weight loss data showed lower rates, when the substrate was worn in the NaCl solution. Decreasing of the friction coefficient should be responsible for these changes. 2. In carbon steel samples and under corrosive environment, NaCl solution acted as a lubricant, which consequently decreased the coefficient of friction, and shear stresses. The absence of Goss and brass components is due to reducing shear stresses in the interface. 3. Under dry wear conditions, {0 1 1}  1 0 0  Goss, {0 1 1}  2 1 1  brass, and {1 1 1}  0 0 1  gamma fiber components were observed in carbon steel samples. The presence of friction forces and shear stresses in the contact area are the main causes for observation of the

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