Research Article Forecasting of Corrosion Properties of ...downloads.hindawi.com/journals/amse/2013/349195.pdf · Forecasting of Corrosion Properties of Steel Wires for Production

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2013, Article ID 349195, 6 pageshttp://dx.doi.org/10.1155/2013/349195

Research ArticleForecasting of Corrosion Properties of Steel Wires forProduction of Guide Wires for Cardiological Treatment

J. Przondziono,1 W. Walke,2 E. Hadasik,1 and R. MBynarski3

1 Faculty of Materials Engineering and Metallurgy, Silesian University of Technology, Krasinskiego 8, 40-019 Katowice, Poland2 Faculty of Biomedical Engineering, Silesian University of Technology, General de Gaulle’a 66, 41-800 Zabrze, Poland3Department of Electrocardiology, Medical University of Silesia, Ziołowa 45/47, 40-635 Katowice, Poland

Correspondence should be addressed to J. Przondziono; [email protected]

Received 16 May 2013; Accepted 31 August 2013

Academic Editor: Delia Brauer

Copyright © 2013 J. Przondziono et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The study presents evaluation of the influence of strain in drawing process and of surface modification on resistance toelectrochemical corrosion of wires made of stainless steel for production of guide wires used in invasive cardiology. The resultsof static tensile test enabled us to determine the course of flow curve of wires made of X10CrNi 18-8 steel as well as mathematicalform of flow stress function. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisationcurves by means of potentiodynamic method. The tests were performed in solution simulating human blood on samples that wereelectrolytically polished and samples that were polished and then chemically passivated. Exemplary anodic polarisation curves weregiven. It was proved that with the applied strain, corrosion properties decrease. It was found that chemical passivation improveswire corrosion characteristics. Statistical analysis showed that there is a significant dependence between corrosion properties(polarisation resistance 𝑅𝑝) and strain 𝜀 applied in drawing process. Functions that present the change 𝑅𝑝 = 𝑓(𝜀) were selected.The issue is of importance to guide wire manufacturers because application of the suggested methodology will enable us to forecastcorrosion characteristics of wire with the required strength drawn with the applied strain.

1. Introduction

Guide wires are indispensable instruments used in low-invasive treatment. Guide wires were initially manufacturedfor vascular applications, but over time they became indis-pensable also in other branches of medicine. They can beused in treatment where percutaneous access inside bloodvessels is required—in angioplasty, in electrocardiology,when inserting electrodes to the heart, and in endoscopicgastrostomy or endourology [1–3]. In the latter one they areused for two purposes: (1) they ensure access to specific partsof urinary system and (2) they are used as guide wires overwhich catheters and stents can be inserted.

Such awide application spectrumdetermined productionof many different types of guide wires. They differ fromone another in construction, dimensions, material they aremade of, and mechanical characteristics, including stiffnessor resistance to cracking [1]. Manufacturers make guidewires in their own catalogue series of types. Most of them

feature elastic flexible tip and stiff or semistiff body. Elastictip enables us to avoid tissue damage and perforation. Mostfrequently, guide wires have the form of long, thin straightwires orwires with “J”-shaped tip. Also guidewires withmorecomplicated construction have found their application. Forexample, in endourological percutaneous nephrolithotripsyor ureterorenoscopy, guide wires consist of both round wiresand springs in which there are thin round wires and flat wires[4–8].

In invasive cardiology, thanks to application of intravas-cular guide wires, it is possible to insert the required instru-ments into blood vessels or, for example, implants, stentsused in angioplasty. During treatment there is no need tocut blood vessels. In electrotherapy, guide wires are used intwo ways. The first one includes accessing the vein, thanks towhich an electrode can be inserted. The second one includesstiffening of the electrode, which facilitates its insertion in therespective place inside the heart.

2 Advances in Materials Science and Engineering

Guide wires must meet a number of requirements. Mostof all, their application must be safe for the patient. Theyshould feature high resistance to electrochemical corrosionin the environment of tissues and saline solutions. Whencoming into contact with blood, they cannot cause any reac-tion. Guide wires should also feature the requiredmechanicalproperties suitable for the respective application. Functionalproperties are dependent on, among other things, chemicalcomposition of the material, its metallurgical purity, andtechnological parameters of wire production process. Thequestion of determination of physical and chemical charac-teristics of guide wire surface is also vital. They should beadapted to the characteristics of human tissue environment.

In case of plastic working, the selection of optimumparameters of wire drawing process is influenced by propercharacteristics of technological plasticity of the material. Itconditions obtaining the structure susceptible to drawingprocess and obtaining a product that features the requiredfunctional characteristics. Plastic strain is accompanied bythe phenomenon of work hardening that is connected withthe increase of flow stress 𝜎𝑝. Hardening causes increaseof strength properties of wire and decrease of its plasticproperties. Correct determination of parameters of plasticworking and obtaining suitable final properties of productsare connected with analysis of the course of function 𝜎𝑝 =𝑓(𝜀), where 𝜀 means strain expressed as a logarithm. Curvesof flow stress change as the function of strain (so-calledflow curves) enables us to forecast behaviour of the materialduring plastic working [9]. Strain applied in drawing processalso has a significant influence on corrosion properties ofwireused for production of guide wires [10, 11].

Proper solution to technological problems regarding pro-duction of guide wires conditions the success of performedtreatment in invasive cardiology. Engineers make use ofwork-hardening curves in order to select such parameters ofdrawing so as to obtain wires with mechanical characteristicsrequired for the respective application. This study is a pro-posal of a similar behaviour in order to forecast corrosioncharacteristics ofwire depending on strain applied in drawingprocess. Methodology presented in this study will enable usto define corrosion properties featured by the wire with therequired strength drawn with the selected strain.

Guide wires in commercial use are manufactured amongother things from stainless steel of X10CrNi 18-8 grade. Thestudy presents the course of flow curve of wires made of thatsteel and mathematical form of flow stress function. Resis-tance to corrosion was evaluated on the ground of registeredanodic polarisation curves by means of potentiodynamicmethod. Tests were made in the solution simulating humanblood on samples that were electrolytically polished andpolished and then chemically passivated. Exemplary anodicpolarisation curves were presented, as well as curves showingthe relation between polarisation resistance as the functionof strain applied in wire drawing process. Performed testsenabled us to determine both the effect of strain during coldworking and theway of surface preparation onwire corrosioncharacteristics.

2. Materials and Methods

Initial material for tests consisted of annealed wire rod madeof X10CrNi 18-8 steel with diameter of 5.65mm.Wire rodwasdrawn to a diameter of 1.5mm. Total logarithmic strain indrawing process was 𝜀 = 2.65. Wire work hardening tookplace during cold working. In the course of strain processsamples for mechanical and corrosion tests were cut off.

Flow stress 𝜎𝑝 of drawn materials is determined on theground of stress-strain curve in tension in the arrangement𝜎𝑟-𝜀, where 𝜎𝑟 is real stress and 𝜀 is strain expressed as alogarithm. In order to determine actual stress, it is necessaryto calculate real cross-section of sample 𝑆 loaded withforce 𝐹. Calculation of real cross-section of sample requiresdetermination of real diameter of sample 𝑑, which is subjectto change due to present elastic and plastic elongation. Forthe load corresponding to proof stress, the value of realstress 𝜎𝑟0.2 was calculated in accordance with the formula (1)[9]

𝜎𝑟0.2 =

𝑅𝑝0.2

[√1/1.002 − ] ⋅ 𝑅𝑝0.2/𝐸]2, (1)

where𝑅𝑝0.2 is proof stress, ] is Poisson’s ratio, and𝐸 is Young’smodulus.

Strength properties, including proof stress, were deter-mined in static uniaxial tension test on testing machineInstron of 1116 type. Next, the course of flow curve of thefunction 𝜎𝑝 = 𝑓(𝜀) was determined.

Wires were then subject to surface modification. Wireselectropolished as well as polished and then chemically pas-sivated in 40% nitric acid surface were selected for tests. Pas-sivation proceeded at the temperature of 65∘C for 20–60min.Prior to polishing and passivation, wires were grounded withabrasive paper with granulation from 80–1200. It enabled usto remove subgrease layers and grease that was left on thesurface after drawing process. Figure 1 shows pictures of wirerod and wire with diameter of 1.5mm after drawing. On thesurface, there is a visible subgrease layer (wire rod) and alayer of grease (wires). If greases had been left there, it wouldpreclude correct execution of electrochemical polishing andpassivation. It would also cause deterioration of corrosioncharacteristics of wires. Pictures of wire surface after plasticworking were taken with electron scanning microscope withfield emission FE SEM S-4200 Hitachi.

Resistance to electrochemical corrosion was evaluated onthe ground of registered anodic polarisation curves by meansof potentiodynamic method [12, 13]. Potentiodynamic testsof wires were performed in artificial blood plasma solution.Stern method was used in order to determine polarisationresistance. Potentiodynamic tests were performed at thetemperature of 𝑇 = 37 ± 1∘C and pH = 7.0 ± 0.2. Saturatedcalomel electrode (SCE) of KP-113 type served as referenceelectrode, whereas platinum electrode PtP-201 was used asauxiliary electrode. Table 1 presents composition of artificialblood plasma.

Advances in Materials Science and Engineering 3

60𝜇m

(a)

60𝜇m

(b)

Figure 1: Surface of wire rod (a) and wire with diameter of 1.5mm (b).

Table 1: Chemical composition of artificial blood plasma solution.

Chemical compound Amount of distilled water, g/LNaCl 6.8CaCl2 0.2KCl 0.4MgSO4 0.1NaHCO3 2.2Na2HPO4 0.126NaH2PO4 0.026

3. Results

Table 2 presents strength properties of wires with selecteddiameters determined in tensile test.

Real stress values 𝜎𝑟0.2 determined in tensile tests, corre-sponding to proof stress, served as the ground for makingflow curve of tested wires and determination ofmathematicalform of flow stress function. The curve was approximatedwith function 𝜎𝑝 = 𝜎𝑝0 + 𝐶𝜀

𝑛 that gives consideration tothe value of stress for initial state (i.e., for annealed wire fordrawing). Mathematical form of flow stress function for thetested steel is as follows:

𝜎𝑝 = 253.1 + 894.6𝜀0.51. (2)

Figure 2 presents flow curve of wires made of X10CrNi18-8 steel (𝜀 means strain in drawing process expressed as alogarithm).

Potentiodynamic tests in artificial blood plasma enabledus to determine how wire resistance to electrochemical cor-rosion changes both in relation to strain applied in drawingprocess and to the way of wire surface preparation. OCPpotential for all tested samples stabilised after 60 minutes.Corrosion test results are shown in Table 3. Figures 3 and 4present selected anodic polarisation curves.

Next, it was determined whether there is a significantrelation between corrosion properties and strain in drawing

0

400

800

1200

1600

2000

0 1 2 3

𝜎p

(MPa

)

𝜀

Figure 2: Flow curve of wire made of X10CrNi 18-8 steel.

process. Figure 5 shows curves obtained on the ground ofselected results of corrosion tests, namely, the change ofpolarisation resistance 𝑅𝑝 as the function of strain appliedin drawing process 𝜀. Functions presenting the change 𝑅𝑝 =𝑓(𝜀) were selected. They look as follows:

(i) electrochemically polished wires

𝑅𝑝 = −118.4𝜀 + 592.5, 𝑅2= 0.886, (3)

(ii) wires that were polished and chemically passivated

𝑅𝑝 = −444𝜀 + 2057.5, 𝑅2= 0.842. (4)

Static analysis proved that significance level 𝑃 < 0.05.

4. Discussion

Experimental determination of flow stress of the materialis executed in one of basic tests: tensile, compression, ortorsion. Indeed, static tensile test is accompanied by strain toosmall to be taken into consideration by engineers who designplastic forming processes; still it is the only possible one to beadopted in case of tests of thin wires. Performed mechanical


Table 2: Strength properties of wire.

Wire diameter 𝑑, mm Logarithmic strain in the drawing process, 𝜀 Tensile strength 𝑅𝑚, MPa Proof stress 𝑅𝑝0.2, MPa5.65 — 604 2523.0 1.27 1607 14032.0 2.22 1827 15071.5 2.65 2178 1653

Table 3: Test results of pitting corrosion resistance.

Wire diameter𝑑, mm

Strain in drawingprocess 𝜀

Breakdownpotential 𝐸𝑏, mV

Polarisationresistance 𝑅𝑝,

kΩcm2

Corrosioncurrent density𝑖corr, 𝜇A/cm

2

Electrochemically polished wires5.6 0 +612 567 0.043.0 1.27 +510 459 0.101.5 2.65 +380 229 0.11

Electrochemically polished and chemically passivated wires5.6 0 +858 2220 0.0123.0 1.27 +778 1230 0.0211.5 2.65 +695 1070 0.024

properties tests enabled us to determine the course of flowcurves and to select flow stress function of drawn wires madeof X10CrNi 18-8 steel.

Performance of potentiodynamic tests enabled us toevaluate the impact of strain in drawing process onwire resis-tance to electrochemical corrosion artificial blood plasmasolution. It was proved that with the applied strain, corrosionproperties decrease. Perforation potential and polarisationresistance decrease, and anodic current density increases.That tendency applies both to electrolytically polished andpolished and then chemically passivated wires.

Annealed wire rod with diameter of 5.65mm featured thehighest corrosion resistance, irrespective of the condition ofthe surface. Perforation potential of polished wire rod was𝐸𝑏 = +612mV and, that of polished and passivated was 𝐸𝑏 =+858mV. The lowest perforation potential was observed inwirewith diameter of 1.5mm(𝐸𝑏 =+380mV for polishedwireand 𝐸𝑏 = +695mV for passivated wire). As strain increased,polarisation resistance also decreased. Polarisation resistancefor polished wires was, respectively, 𝑅𝑝 = 576 kΩcm

2 (wirerod) and 𝑅𝑝 = 229 kΩcm2 (wire with diameter of 1.5mm).Polarisation resistance of polished and passivated wire rodwas 𝑅𝑝 = 2220 kΩcm

2 and of polished and passivated wirewith diameter 1.5mm was 𝑅𝑝 = 1070 kΩcm

2.Plastic strain in drawing process caused increase of cor-

rosion current density for both types of wires, polished andpolished and then passivated. Corrosion current density ofpolished wire rod was 𝑖corr = 0.04 𝜇A/cm

2 and of polishedand passivated was 𝑖corr = 0.012 𝜇A/cm

2. Wire with diameter𝑑 = 1.5mm featured the highest corrosion current density.It was 𝑖corr = 0.11 𝜇A/cm

2 for polished wire and 𝑖corr =0.024 𝜇A/cm2 for passivated wire.

Presented results show explicitly that chemical passiva-tion substantially improved wire resistance to electrochemi-cal corrosion in artificial blood plasma. Corrosion propertiesof passivated wires are higher than those of wires that weresubject only to electrolytic polishing.

Static analysis showed that there is a significant depen-dence between corrosion properties (polarisation resistance)and strain applied in drawing process. Presented curvesand functional relations give the ground to conclusionsrelated to polarisation resistance of wire subject to surfacetreatment. The value of polarisation resistance shows thatit was justifiable to use chemical passivation in case ofwires for production of cardiologic guide made of X10CrNi18-8 steel.

Presented curves represent correctly the results obtainedexperimentally. The greatest differences of polarisation resis-tance can be observed for wire with initial diameter. It mustbe highlighted that functions presented in the paper wereelaborated for one heat. To transform them into universalrelations for stainless steel X10CrNi 18-8, it is necessary torepeat the tests for a bigger number of heats.

5. Summary and Conclusions

The study proves that increase of strain in drawing processof wires made of stainless steel X10CrNi 18-8 causes decreaseof their resistance to electrochemical corrosion in artificialblood plasma. Moreover, it was observed that chemical pas-sivation improves wire corrosion characteristics.

Potentiodynamic test results also enabled us to obtainfunctional relations showing the influence of strain in draw-ing process on the change of polarisation resistance. It must

Advances in Materials Science and Engineering 5

−2−3−4−5−6−7−8−9−10

−100 0 +100 +200 +300 +400 +500 +600 +700 +800 +900E (mV)

log

A/c

m2

(a)

−2−3−4−5−6−7−8−9−10

−100 0 +100 +200 +300 +400 +500 +600 +700 +800 +900E (mV)

log

A/c

m2

(b)

Figure 3: Anodic polarisation curve recorded for wire rod (𝑑 = 5.65mm) electropolished (a) and passivated (b).

−2−3−4−5−6−7−8−9−10

−100 0 +100 +200 +300 +400 +500 +600 +700 +800 +900E (mV)

log

A/c

m2

(a)

−2−3−4−5−6−7−8−9−10

−100 0 +100 +200 +300 +400 +500 +600 +700 +800 +900E (mV)

log

A/c

m2

(b)

Figure 4: Anodic polarisation curve recorded for wire 𝑑 = 1.5mm electropolished (a) and passivated (b).

0

200

400

600

800

0 1 2 3

Rp

(kΩ

cm2)

𝜀

(a)

0

600

1200

1800

2400

0 1 2 3

Rp

(kΩ

cm2)

𝜀

(b)

Figure 5: Dependence of polarisation resistance on strain in the drawing process: (a) of electrochemically polished wire and (b) ofelectrochemically polished and passivated wire.

be mentioned that presented functional relations are not ofuniversal character and refer only to wires made of X10CrNi18-8 steel tested in artificial blood plasma. If they are to beapplied either to wires or other materials (e.g., other gradesof steel, titanium alloys, cobalt alloys, alloys with elasticmemory effect, andmany other) or goods for other purposes,it is necessary to perform similar test for wires made ofthe respective material in another environment simulatinghuman body saline (artificial urine solution, artificial saliva,and Tyrode or Ringer solution).

Problematic aspects presented in the study are crucialfor process engineers who deal with designing wire drawingprocesses for medicine, as the issue of correct descriptionof material plasticity is tightly connected with the selectionof optimum parameters of wire production technologicalprocess. That issue is equally important to guide wire man-ufacturers, because if the respective curves or functions areto be applied, it is possible to forecast in advance corrosion

characteristics of wire with the required strength drawn withthe applied strain.

To sum up, it must be highlighted that proper descriptionof flow stress function is one of the elements that determineacquisition of proper characteristics of technological plas-ticity of materials. These characteristics constitute currentlythe ground for databases for computer simulation of plasticworking processes. Such bases could be completed withfunctional relations 𝑅𝑝 = 𝑓(𝜀) determined for various metal-lic biomaterials adjusted to human tissue environment invarious body saline solutions. Then they could be used byprocess engineers and manufacturers of goods produced bymeans of cold working for various medical purposes. Forexample, whenmanufacturing a product (strip, bar, and wire,etc.) with the required mechanical characteristics, databasewill enable us to read both the value of necessary strainapplied in processing and polarisation resistance correspond-ing to such strain that the respective biomaterial will feature.


That innovative proposal regarding creation of databaseswhich take into account corrosive properties of metallicmaterials for medicine would make an extremely useful toolin designing technological processes of biomaterials.

Acknowledgment

This project was financed from the funds of the NationalScience Centre in Cracow, Poland.

References

[1] P. A. Schneider, Endovascular Skills: Guidewire and CatheterSkills for Endovascular Surgery, Informa Healthcare, New York,NY, USA, 2009.

[2] P. Fritzsche, M. Senac, and J. D. Moorhead, “Guide wire probetechnique of the urinary tract,” RadioGraphics, vol. 1, no. 2, pp.38–48, 1981.

[3] A. Patriciu, D. Mazilu, H. S. Bagga, D. Petrisor, L. Kavoussi,and D. Stoianovici, “An evaluation method for the mechanicalperformance of guide-wires and catheters in accessing theupper urinary tract,” Medical Engineering and Physics, vol. 29,no. 8, pp. 918–922, 2007.

[4] J. Przondziono, R. Młynarski, J. Szala, and A. Kur, “Charac-teristics of leaders used in heart pacemakers implantation,”Inzynieria Biomateriałow, vol. 13, no. 100-101, pp. 56–58, 2010.

[5] J. Przondziono and W. Walke, “Potentiodynamic studies ofstainless steel wire for endourology,” Archives of MaterialsScience and Engineering, vol. 35, no. 1, pp. 21–28, 2009.

[6] J. Przondziono, J. Szala, and J. Kawecki, “Characteristics ofguidewire used in percutaneous nephrolithotripsy,” InzynieriaBiomateriałow, vol. 9, no. 58–60, pp. 178–180, 2006.

[7] E. Grzegorczyk, B. Młocek, A. Sołtysek, A. Szuła, and J.Przondziono, “Properties of wire used in ureterorenscopy,”Inzynieria Biomateriałow, vol. 9, no. 58–60, pp. 181–183, 2006.

[8] F. Desgrandchamps, P. Pedron, P. Hoffmann, P. Teillac, andA. L.E. Duc, “A comparative study of guidewire electrical resistance,”British Journal of Urology, vol. 80, no. 3, pp. 390–391, 1997.

[9] J. Przondziono, D.Halaczek, and J. Szymszal, “Determination ofthe flow curves of austenite steel wire in the drawing process,”Archives of Civil and Mechanical Engineering, vol. 7, no. 1, pp.85–91, 2007.

[10] W. Walke and J. Przondziono, “Influence of hardening andsurface modification of endourological wires on corrosionresistance,”Acta of Bioengineering and Biomechanics, vol. 14, no.3, pp. 93–99, 2012.

[11] J. Przondziono, “The effect of strain hardening on resistance toelectrochemical corrosion of wires used in cardiology,” Hutnik,vol. 78, no. 8, pp. 663–666, 2011 (Polish).

[12] J. Szewczenko and J. Marciniak, “Corrosion of Cr-Ni-Mo steelimplants electrically stimulated,” Journal of Materials ProcessingTechnology, vol. 175, no. 1-3, pp. 404–410, 2006.

[13] Z. Paszenda, “Application problems of implants used in inter-ventional cardiology,” Advances in Soft Computing, vol. 47, pp.15–27, 2008.

Submit your manuscripts athttp://www.hindawi.com

ScientificaHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation http://www.hindawi.com Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation http://www.hindawi.com Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials

Documents

Research Article Forecasting of Corrosion Properties of ...downloads.hindawi.com/journals/amse/2013/349195.pdf · Forecasting of Corrosion Properties of Steel Wires for Production