wear and corrosion wear of medium carbon steel and 304 stainless steel

Wear 260 (2006) 116–122

Wear and corrosion wear of medium carbon steel and 304 stainless steel

M. Reza Batenia,∗, J.A. Szpunara,1, X. Wangb,2, D.Y. Li b,2

a Department of Mining, Metals and Materials Engineering, McGill University, M.H. Wong Building, 3610 University, Montreal, Que., Canada H3A 2B2b Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alta., Canada T6G 2G6

Received 12 January 2004; received in revised form 27 August 2004; accepted 20 December 2004Available online 5 March 2005

Abstract

Wear and corrosive wear involve mechanical and chemical mechanisms and the combination of these mechanisms often results in significantmutual effects. In this paper, tribological behavior, X-ray peak broadening, and microstructure changes of carbon steel AISI 1045 and stainlesssteel AISI 304 samples under simultaneous wear and corrosion were investigated and the results were compared with those obtained from drywear tests. 3.5 wt.% NaCl solution was used as the corrosion agent and a pin-on-disk tribometer was employed to perform wear and corrosivewear tests.

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X-ray diffraction measurements have shown that by increasing the applied load, the worn surfaces of carbon steel sampleonstant strain at which fracture and wear occurred. Whereas in 304 stainless steel samples, by increasing the applied load, b-ray diffraction peaks was decreased.Wear tests of carbon steel and stainless steel samples have shown smaller weight losses and lower friction coefficient in the

orrosive environment. Study of worn surfaces suggested that depending on wear environment and applied load, different featuechanisms were involved.2005 Elsevier B.V. All rights reserved.

eywords:Corrosive wear; Wear; Tribology; friction; X-ray peak broadening; Strain

. Introduction

Wear and corrosion damage to materials used in min-ng, metals and materials processing, directly or indirectly,mpact the nation financially in terms of material loss, as-ociated equipment downtime for repairing and finally theeplacement of worn and corroded components[1,2]. Wearnd corrosion wear experiments on AISI 304 stainless steelhowed that corrosion played a minor role on corrosive wearf the stainless steel in synthetic Ni–Cu mine water and syner-etic effects were very small. However, the synergetic effectsere quite pronounced on alloy steels[2]. The interactions

∗ Corresponding author. Tel.: +1 514 398 4755; fax: +1 514 398 4492.E-mail addresses:[email protected] (M.R. Bateni),

[email protected] (J.A. Szpunar), [email protected] (X. Wang),[email protected] (D.Y. Li).1 Tel.: +1 514 398 4755; fax: +1 514 398 4492.2 Tel.: +1 780 492 6750; fax: +1 780 492 2881.

among wear and corrosion could significantly increaseweight losses and reduction of either wear or corrosion cconsiderably decrease the total weight loss[3]. In order todecide whether to choose materials according to theirchanical properties or corrosive characteristics, for anyticular applications, sufficient information will be necess[4].

The chemical degradation of materials, corrosion,stroys the materials by chemical reactions with aggreenvironments, mostly liquid or gases. In contrast, thechanical failure is the end-point of elastic and/or plasticformation processes[5].

Corrosive wear takes place when an active environresults in material dissolution or produces a reaction proon one or both of the rubbing surfaces. The reaction prodare usually poorly bonded to the surface and further rubcauses their removal. Corrosion wear requires both corrand rubbing. The growth rate of corrosion product, oxide fidecreases with time, and therefore unless the oxide fi

043-1648/$ – see front matter © 2005 Elsevier B.V. All rights reserved.oi:10.1016/j.wear.2004.12.037

M.R. Bateni et al. / Wear 260 (2006) 116–122 117

removed by rubbing, the corrosion of metal rapidly becomessmall[6].

Sliding contact between the surfaces of ductile materialsis often accomplished by severe plastic deformation of ma-terials, adjacent to the contact surface. The process of debrisformation, especially in un-lubricated systems, is closely re-lated to magnitude and distribution of local strain and straingradients as well as the variation of stress within the deformedsubsurface zones[7]. On the other hand, the ridges on bothsides of an isolated wear track are plastically deformed re-gions containing a high density of dislocations, which presenta high internal energy and in the presence of corrosive envi-ronment, corrosion attack occurs in the deformed layer veryquickly [8].

X-ray diffraction can be used to determine both macro-scopic and microscopic residual stresses. Macro-stresses aredetermined from the shift in the position of diffraction peaks.While micro-stresses, could be quantified from the broaden-ing of the diffraction peaks. As a metal is cold worked, thedislocation density increases, thereby perfectly crystalline ar-eas are decreased and the average micro-strain in the crystallattice is increased. The reduced crystallite size and increasedmicro-strain both produce broadening of diffraction peaks[9].

For many significant applications, the actual understand-ing of the synergism between wear and corrosion processes ins r-f andm tain-l itionsh

2

pec-i inlesssf reas-i rnals pro-c l samp , re-s d ins

eart s thec r testw lesw about1 anda entsw

steels testsw 71N

and for all experiments the sliding distance of 160 m wasused.

X-ray diffraction (XRD) and scanning electron micro-scope (SEM) were used for determination of X-ray peakbroadening, microstructure of worn surfaces, and wear mech-anisms. XRD patterns were recorded using Cu K� radiationat a step scan mode of 0.02◦.

3. Results and discussion

3.1. X-ray peak broadening of the worn surfaces

The K� radiation generally used for residual stress mea-surement produces overlapped double diffraction peaks. TheK� doublet (consisting of peaks produced by K�1 and K�2radiations) could be separated to determine the width of thestronger peak generated by K�1. Most of the difficulties en-countered in determining both the diffraction peak positionand width can be overcome if the measured diffraction peakscan be accurately described by a suitable function fitted byregression analysis. Pearson VII functions, which are bell-shaped curves ranging from Cauchy to Gaussian distribu-tions, have been shown to describe accurately the profiles ofdiffraction peaks in the back-reflection region used for resid-ual stress measurement[11]. The K� diffraction peak po-s ttedf thews pliedl ondi-t es ac t fur-t ct onX

rfacel lesst erf on.B tarts

ples.

liding contacts is rather limited[10]. In this paper, wear peormances, frictional behavior, X-ray peak broadeningicrostructure of medium carbon steel and austenitic s

ess steel samples under wear and corrosion wear condave been investigated.

. Materials and experimental techniques

Carbon steel AISI 1045 and stainless steel AISI 304 smens were used as experimental specimens. Both stateel and carbon steel samples were annealed at 875± 25◦Cor an hour. The aim of annealing treatment was decng and relieving internal stresses. The origins of the intetresses were previous mechanical working and formingesses. The harness of stainless steel and carbon steeles, after annealing treatment, were 179 and 163 HBpectively and carbide precipitations were not observetainless steel sample after annealing treatment.

A pin-on-disk tribometer was employed to perform wests. AISI 3Cr12 steel Pins (220 HB) were employed aounter face. The dimension of pin specimens for weaas 6 mm× 12 mm× 40 mm. Test surface of the sampas polished on a lathe and the final roughness was.0�m. Wear tests were conducted at room temperaturevelocity of 0.53 m/s. The contact area in all experimas 72 mm× 72 mm.Corrosion wear behavior of carbon steel and stainless

amples were studied in 3.5 wt.% NaCl solution. Wearere carried out under different loads of 9.6, 32, 54 and

-

1ition, width and intensity can be determined from the fiunction. The diffraction peak width is usually taken byidth at half value of maximum intensity (FWHM).Fig. 1hows the variation of X-ray peak broadening against apoad for carbon steel samples under corrosive and dry cions. By increasing the applied load, broadening reachonstant value at which fracture occurred. It seems thaher increasing of applied load does not have any effe-ray peak broadening.Corrosive media more easily removed the stressed su

ayers and X-ray peak broadening of these samples ishan dry tested samples (Fig. 1). On the other hand, lowriction led to less wear when worn in the NaCl solutiy increasing the applied load, X-ray peak broadening s

Fig. 1. X-ray peak broadening vs. applied load for carbon steel sam

118 M.R. Bateni et al. / Wear 260 (2006) 116–122

Fig. 2. X-ray peak broadening vs. applied load for stainless steel samples.

to increase. As the load increased, the contribution due tocorrosion changed. When wear continuously occurred underhigh loads, the percentage of corrosion effects became lessimportant, whereas, under lower loads, the part of corrosioneffects were high[7].

Fig. 2 shows the effect of applied load on X-ray peakbroadening of 304 stainless steels in both corrosive andnon-corrosive environments. Stainless steel possesses ex-cellent corrosion resistance in the absence of wear. How-ever, it readily wears and corrodes when abrasive particlesremove its corrosion resistance passive film[3]. Corrosionwear was preceded by successive stages of buildup and re-moval of oxides on the rubbing surfaces. Under dynamicconditions or rubbing, reaction Fe/Fe(OH)2 is thermody-namically favored in the early stages of film formation[5].This reaction led to re-passivation of the abraded surface.The passive state only existed for a short time due to con-tinual abrading. Accordingly, corrosion proceeded as longas rubbing was taking place. Under this condition, layer-rupturing action, which is constant at fixed conditions ofabrasion, became rate controlling for corrosion-wear process[5].

On the other hand, during the wear test, temperature in-creased at the contact area between substrate and counterface. Austenitic stainless steels have shown the lowest ther-mal conductivity among carbon steels and other stainlesss areasw t areas.I ermalc accu-m t ands asonsf eas-i n ands whenw andf , thed n thato

Fig. 3. Weight losses of the samples under dry wear and corrosive wear: (a)1045 carbon steel; (b) 304 stainless steel.

3.2. Tribological behavior

Wear performances of carbon steel and stainless steel sam-ples during both dry sliding and corrosion wear in NaCl solu-tion were evaluated.Fig. 3illustrates weight losses of carbonsteel and stainless steel samples under different conditions.As the load is increased, the weight loss is increased. It isobserved that under corrosive wear condition, weight loss issmaller than dry wear. This could be attributed to the follow-ing reasons:

(1) The dilute NaCl solution was not very corrosive andtherefore did not result in severe synergistic attack ofwear and corrosion. On the other hand, the NaCl solu-tion reduced the friction between the substrate and thecounter-face, which consequently decreased the wearingforce, thus leading to less damage to the substrate.

(2) Heat generation, due to friction, generally resulted insoftening of the substrate and thus increased the weightloss. The NaCl solution decreased the temperature rise,which could further reduced the weight loss.

Variation of friction coefficient versus time in carbon steeland stainless steel samples at a load of 9.6N are shown inFigs. 4 and 5. It is observed that the coefficient of fric-tion of carbon steel sample shows a decrease under corro-s hef hichc theo tiono filma d the

teels. Therefore, by increasing the load, the contactere increased and more heat was generated at contac

ncreasing the temperature at the contact area and low thonductivity of austenitic stainless steels, caused heatulation at the contact area. The accumulation of hea

ubsequent stress relief process could be the main reor decreasing X-ray diffraction peak broadening by incrng the applied load. Such process of heat accumulatioubsequent stress relief could however, be suppressedorn in the NaCl solution due to the reduced friction

aster heat conduction through the solution. As a resultecrease in the XRD peak broadening was smaller thaccurred in the case of dry wear test (Fig. 2).

ive environment (Fig. 4). The corrosive solution reduced triction between the substrate and the counter-face, wonsequently decreased the coefficient of friction. Onther hand, in the presence of NaCl solution, the formaf surface oxide layer was accelerated. Such an oxidected as intermediate layer on the surface, which reduce


Fig. 4. Variation of friction coefficient vs. time in carbon steel sample: (a)dry condition; (b) corrosive condition.

coefficient of friction[12,13]. The ease of formation of thesurface oxide layer and decreasing metallic contact betweensubstrate and counter-face are main reasons for reducing thecoefficient of friction in the presence of corrosive environ-ment. On the other hand, in the presence of corrosive solu-tion, less fluctuations in the friction coefficient is observed.The NaCl solution reduced the adhesion and friction betweenthe substrate and the counter-face, which consequently de-creased the wearing force, thus leading to less fluctuation infriction coefficient. The variation of friction coefficient ver-sus sliding distance of stainless steel samples shows inFig. 5.Higher coefficient of friction value in stainless steel samplesis due to stronger adhesion bonds. A remarkable stick-slip be-havior in friction coefficient of stainless steel samples underdry wear and corrosive wear conditions is observed (Fig. 5).When two surfaces contacted each other, the adhesion tookplace at the contact area and caused stick to take place. Thefriction force and, consequently, the friction coefficient rosesharply. At some points the tangential forces were sufficientto overcome the adhesive bonds at the interface, fracture ac-crued, and the friction force dropped sharply. As long as thewear test continued, adhesion, force build up, interfacial ad-

Fig. 5. Variation of friction coefficient vs. time in stainless steel sample: (a)dry condition; (b) corrosive condition.

hesion bonds fracture and slip process repeated, respectively[14].

The variation of specific wear rate versus applied load isshown inFig. 6. By increasing the applied loads, specificwear rates stared to decrease and approach to constant val-ues, steady-state wear. On the other hand, wear mechanism

Fig. 6. Variation of specific wear rate vs. applied load.


Fig. 7. Wear surface of carbon steel sample after dry wear test, under 9.6Nload.

changes from sever regime to mild one. At higher loads, ahard surface layer is formed, most likely martensite, on sur-faces because of high flash temperature, followed by rapidquenching as the heat was conducted into the underlying bulkmaterial. The higher flash temperature also caused the localoxidation rate to increase[15]. On the other hand, increasingthe applied load caused work hardening of subsurface layersand the surface oxide layer supported by the hardened sub-layers. The higher oxidation rate formed thicker oxide layeron the surface. The formed oxide layer prevented further di-rect metallic contact and reduced the specific wear rates.

3.3. Microstructure of worn samples

Worn surface of carbon steel sample in the presence ofcorrosive environment indicates the formation of plate-likedebris on the surface (Fig. 7). The presence of plate like de-bris has confirmed that the delamination took place in thosesamples[16,17]. The delamination wear process consists ofplastic deformation of a surface layer of finite thickness, voidnucleation and crack propagation below the surface[18]. In-creasing the applied load did not have any effects on wearmechanisms.

Scanning electron microscopy (SEM) image of the sub-surface layers of carbon steel sample under dry wear testshows the presence of subsurface cracks and deformed lay-e ptho oad,t d thatv oca-t sur-f w thes sitesw t thea

rackns e ap-p aring

Fig. 8. Cross-section of carbon steel sample under dry wear test, 71N load.

area is the real contact area and wear and friction forces aredirectly related to that area. That area varies with the numberof contacting points, the roughness, and the elasto-plastic de-formation of each contact point. During wear process, someparts of the surface area loss their surface film due to a me-chanical loading[10]. In the presence of corrosive environ-ment, the formation of galvanic cell might be responsible forthe formation of crack networks on the worn surface. Thegalvanic cells were formed due to the abraded area on thesurface as anode and undamaged area as cathode.

In the presence of corrosive environment, the formationof cracks and voids is observed in the cross-section (Fig. 10).Corrosive media reduced the friction forces between two sur-faces and the depth of the deformed layer decreased. How-ever, regardless of the formation of cracks and voids due tothe synergism of wear and corrosion, the total weight loss issmaller than that under dry wear condition. It seems that thereduction of friction forces by the NaCl solution might beresponsible for less damage on the specimen surface, whenworn in the NaCl solution than in the specimen treated with-out it.

F under7

rs under the surface (Fig. 8). The cracks propagate at a def 5–30�m under the surface. By increasing the applied l

he depth of the deformed layer increased. It is reasoneoids around inclusions and any imperfections like dislions can be nucleated only at a certain depth from theace. Indeed, cracks nucleated at a finite distance belourface and the location of possible crack nucleationas affected by the magnitude of the normal forces asperity-surface contact[19].

Under corrosive condition, the presence of surface cetworks is shown on the worn surface (Fig. 9). When twourfaces came into contact with each other, only part of tharent contact area carried the applied load. This load be

ig. 9. Wear surface of carbon steel sample after corrosive wear test,1N load.


Fig. 10. Cross-section of carbon steel sample under corrosive wear test, 71Nload.

Studying of worn surfaces of stainless steel under dry weartests have shown that at lower loads, delamination is thepredominant wear mechanism. Whereas, by increasing theapplied load, the adhesive wear was observed more often.The cross-section of worn stainless steel sample under drycondition is presented inFig. 11. The presence of voids un-der the surface is illustrated. Under repeated load, the voidswere enlarged and linked. By increasing the applied load,the number of voids considerably increased. On the otherhand, highly deformed areas were not observed under thesurface. The higher hardness and lower ductility of stainlesssteel and adhesion wear mechanism are the main reasonsfor lack of highly deformed areas below the specimen sur-face.

SEM micrograph of worn surface of stainless steel sam-ple under corrosive environment shows inFig. 12. Underlower loads, the presence of plate like particles was observed.Whereas, abrasive wear and adhesive wear became predomi-nant wear mechanisms by increasing the applied load to 71N.The presence of protective chromium oxide layer on the sur-face of stainless steel is the main reason for changing wearmechanism. At lower loads, the oxide layer lowered adhe-

F t, 71Nl

Fig. 12. Wear surface of stainless steel sample under corrosive wear test,71N load.

sion between two surfaces. However, as the load increased,the oxide layer broke down and metallic contact was createdbetween two surfaces. The break down of the oxide layerand metallic contact are main reasons for the existence ofadhesion wear. On the other hand, the relative motion of twosurfaces induced severe plastic deformation and rupture ofdeformed junctions produced hard wear debris. The plough-ing actions of hard wear particles could caused abrasive wearmechanism[20].

4. Conclusions

1. By increasing the applied load, X-ray peak broadening ofworn carbon steel surfaces, under both dry and corrosiveconditions, reached to a constant value.

2. Increasing of temperature at the contact area and low ther-mal conductivity of 304 stainless steels are responsiblefor heat accumulation and consequently stress relief andlower X-ray peak broadening in the deformed surface lay-ers.

3. The weight loss and XRD peak broadening were lowerwhen the substrate was worn in the NaCl solution. De-creasing of the friction coefficient should be responsiblefor these changes.

4. Studying of worn surfaces has shown that delaminationated

con-wear

5 r andyersower, thewearwere

6 sam-e

ig. 11. Cross-section of stainless steel sample under dry wear tesoad.

is main wear mechanism in carbon steel sample trewithout corrosive solution, whereas under corrosiveditions, the surface damage was caused by synergy ofand corrosion attacks.

. In stainless steel samples tested under both dry weacorrosion wear condition, delamination of surface lawas predominant wear mechanism during testing at lloads. By increasing the load, under dry wear testsadhesion wear was observed and under corrosionconditions, the combined adhesive and abrasive wearidentified.

. High wear rates of carbon steel and stainless steelples, of order 10−3 to 10−4 mm3/N m, could be due to th


synergetic effects of different wear mechanisms, such asmechanical, oxidation, and corrosive wear.

Acknowledgement

The authors acknowledge the financial support fromthe Natural Science and Engineering Research Council ofCanada (NSERC).

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wear and corrosion wear of medium carbon steel and 304 stainless steel

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