Research Papers

Biocompatibility and Corrosion Response of Laser Joined NiTi to Stainless Steel Wires

[+] Author and Article Information
Grant Brandal

Mechanical Engineering Department,
Columbia University,
500 W 120th Street, Mudd Rm 220,
New York, NY 10023
e-mail: gbb2114@columbia.edu

Y. Lawrence Yao

Fellow ASME
Columbia University,
New York, NY 10023
e-mail: yly1@columbia.edu

Syed Naveed

Endoscopy Division,
Boston Scientific Corporation,
Marlborough, MA 01752
e-mail: Syed.naveed@bsci.com

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received May 6, 2014; final manuscript received January 20, 2015; published online March 5, 2015. Assoc. Editor: Wei Li.

J. Manuf. Sci. Eng 137(3), 031015 (Jun 01, 2015) (9 pages) Paper No: MANU-14-1272; doi: 10.1115/1.4029766 History: Received May 06, 2014; Revised January 20, 2015; Online March 05, 2015

The biocompatibility of nickel titanium (NiTi) wires joined to stainless steel (SS) wires via laser autogenous brazing has been evaluated. The laser joining process is designed to limit the amount of mixing of the materials, thus preventing the formation of brittle intermetallic phases. This process has the potential for manufacturing implantable medical devices; therefore, the biocompatibility must be determined. Laser joined samples underwent nickel release rate, polarization, hemolysis, and cytotoxicity testing. Competing effects regarding grain refinement and galvanic effects were found to influence the corrosion response. After 15 days of exposure to a simulated body fluid, the total nickel released is less than 2 ug/cm2. Numerical modeling of the corrosion currents along the wires, by making use of polarization data, helped to explain these results. Microbiological testing found a maximum hemolytic index of 1.8, while cytotoxicity tests found a zero toxicity grade. All of these results indicate that the autogenous laser brazing process results in joints with good biocompatibility.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.


Duerig, T., Pelton, A., and Stöckel, D., 1999, “An Overview of Nitinol Medical Applications,” Mater. Sci. Eng. A, A273(275), pp. 149–160. [CrossRef]
Dos Santos, R. L., Pithon, M. M., Nascimento, L. E. A. G., Martins, F. O., Teresa, M., Romanos, V., and Nojima, L. I., 2011, “Cytotoxicity of Electric Spot Welding: An In Vitro Study,” Dent. Press J. Orthod., 16(3), pp. 1–6, Available at http://dpjo.dentalpresspub.com/editions/v16n3/
Vannod, J., 2011, Laser Welding of Nickel-Titanium and Stainless Steel Wires: Processing, Metallurgy and Properties, Ph.D. thesis, Ecole Polytechnique Federale De Lausanne, Lausanne, Switzerland.
Cui, Z. D., Man, H. C., and Yang, X. J., 2005, “The Corrosion and Nickel Release Behavior of Laser Surface-Melted NiTi Shape Memory Alloy in Hanks' Solution,” Surf. Coat. Technol., 192(2–3), pp. 347–353. [CrossRef]
Surmenev, R. A., Ryabtseva, M. A., Shesterikov, E. V., Pichugin, V. F., Peitsch, T., and Epple, M., 2010, “The Release of Nickel From Nickel-Titanium (NiTi) is Strongly Reduced by a Sub-Micrometer Thin Layer of Calcium Phosphate Deposited by RF-Magnetron Sputtering,” J. Mater. Sci. Mater. Med., 21(4), pp. 1233–1239. [CrossRef] [PubMed]
Hang, R., Ma, S., Ji, V., and Chu, P. K., 2010, “Corrosion Behavior of NiTi Alloy in Fetal Bovine Serum,” Electrochim. Acta, 55(20), pp. 5551–5560. [CrossRef]
Zhang, C., Sun, X., Zhao, S., Yu, W., and Sun, D., 2014, “Susceptibility to Corrosion and In Vitro Biocompatibility of a Laser-Welded Composite Orthodontic Arch Wire,” Ann. Biomed. Eng., 42(1), pp. 222–230. [CrossRef] [PubMed]
Li, H. M., Sun, D. Q., Cai, X. L., Dong, P., and Wang, W. Q., 2012, “Laser Welding of TiNi Shape Memory Alloy and Stainless Steel Using Ni Interlayer,” Mater. Des., 39, pp. 285–293. [CrossRef]
Brandal, G., Satoh, G., Yao, Y. L., and Naveed, S., 2013, “Beneficial Interface Geometry for Laser Joining of NiTi to Stainless Steel Wires,” ASME J. Manuf. Sci. Eng., 135(6), p. 061006. [CrossRef]
Satoh, G., and Yao, Y. L., 2011, “Laser Autogenous Brazing—A New Method for Joining Dissimilar Metals,” Proceedings of the 30th International Congress on the Applications of Lasers and Elecro-Optics, Lake Buena Vista, FL, pp. 315–324.
Cacciamani, G., De Keyzer, J., Ferro, R., Klotz, U. E., Lacaze, J., and Wollants, P., 2006, “Critical Evaluation of the Fe–Ni, Fe–Ti and Fe–Ni–Ti Alloy Systems,” Intermetallics, 14(10–11), pp. 1312–1325. [CrossRef]
Li, X., Wang, J., Han, E., and Ke, W., 2007, “Influence of Fluoride and Chloride on Corrosion Behavior of NiTi Orthodontic Wires,” Acta Biomater., 3(5), pp. 807–815. [CrossRef] [PubMed]
Wang, J., Li, N., Han, E., and Ke, W., 2006, “Effect of pH, Temperature and Cl- Concentration on Electrochemical Behavior of NiTi Shape Memory Alloy in Artificial Saliva,” J. Mater. Sci. Mater. Med., 17(10), pp. 885–890. [CrossRef] [PubMed]
Petro, R., and Schlesinger, M., 2013, Applications of Electrochemistry in Medicine, Springer, Boston, MA.
Expert Group on Vitamins and Minerals, 2003, “Safe Upper Levels for Vitamins and Minerals,” Committee on Toxicity, Food Standards Agency, Report.
Armitage, D. A., Parker, T. L., and Grant, D. M., 2003, “Biocompatibility and Hemocompatibility of Surface-Modified NiTi Alloys,” J. Biomed. Mater. Res. A, 66(1), pp. 129–137. [CrossRef] [PubMed]
Wataha, J. C., Lockwood, P. E., Marek, M., and Ghazi, M., 1999, “Ability of Ni-Containing Biomedical Alloys to Activate Monocytes and Endothelial Cells in Vitro,” J. Biomed. Mater. Res., 45(3), pp. 251–257. [CrossRef] [PubMed]
Fehlner, F., and Graham, M., 2002, “Thin Oxide Film Formation on Metals,” Corrosion Mechanisms in Theory and Practice, P.Marcus, ed., Marcel Dekker, New York, pp. 171–187.
Michiardi, A., Aparicio, C., Planell, J. A., and Gil, F. J., 2006, “New Oxidation Treatment of NiTi Shape Memory Alloys to Obtain Ni-Free Surfaces and to Improve Biocompatibility,” J. Biomed. Mater. Res. B, 77(2), pp. 249–256. [CrossRef]
Tan, L., 2003, “Corrosion and Wear-Corrosion Behavior of NiTi Modified by Plasma Source Ion Implantation,” Biomaterials, 24(22), pp. 3931–3939. [CrossRef] [PubMed]
Trépanier, C., Tabrizian, M., Yahia, L. H., Bilodeau, L., and Piron, D. L., 1998, “Effect of Modification of Oxide Layer on NiTi Stent Corrosion Resistance,” J. Biomed. Mater. Res., 43(4), pp. 433–440. [CrossRef] [PubMed]
Sohmura, T., 1988, “Improvement in Corrosion Resistance in Ti–Ni Shape Memory Alloy for Implant by Oxide Film Coating,” Proceedings of the World Biomaterial Congress, Kyoto, Japan, p. 574.
Undisz, A., Schrempel, F., Wesch, W., and Rettenmayr, M., 2012, “Mechanism of Oxide Layer Growth During Annealing of NiTi,” J. Biomed. Mater. Res. A, 100(7), pp. 1743–1750. [CrossRef] [PubMed]
Villermaux, F., Tabrizian, M., Yahia, L., Meunier, M., and Piron, D. L., 1997, “Excimer Laser Treatment of NiTi Shape Memory Alloy Biomaterials,” Appl. Surf. Sci., 109-110, pp. 62–66. [CrossRef]
Nishida, M., Wayman, C. M., and Honma, T., 1986, “Precipitation Processes in Near-Equiatomic TiNi Shape Memory Alloys,” Metall. Trans. A, 17(9), pp. 1505–1515. [CrossRef]
Verdian, M. M., Raeissi, K., Salehi, M., and Sabooni, S., 2011, “Characterization and Corrosion Behavior of NiTi–Ti2Ni–Ni3Ti Multiphase Intermetallics Produced by Vacuum Sintering,” Vacuum, 86(1), pp. 91–95. [CrossRef]
Landolt, D., 2002, “Introduction to Surface Reactions: Electrochemical Basis of Corrosion,” Corrosion Mechanisms in Theory and Practice, P.Marcus, ed., Marcel Dekker, New York, pp. 1–17.
Jones, D. A., 1992, Principles and Prevention of Corrosion, MacMillan, New York.
Oldfield, J. W., 1988, Galvanic Corrosion, ASTM, Philadelphia, PA.
Deshpande, K. B., 2011, “Numerical Modeling of Micro-Galvanic Corrosion,” Electrochim. Acta, 56(4), pp. 1737–1745. [CrossRef]
Chan, C. W., Man, H. C., and Yue, T. M., 2012, “Susceptibility to Stress Corrosion Cracking of NiTi Laser Weldment in Hanks' Solution,” Corros. Sci., 57, pp. 260–269. [CrossRef]
Yan, X.-J., and Yang, D.-Z., 2006, “Corrosion Resistance of a Laser Spot-Welded Joint of NiTi Wire in Simulated Human Body Fluids,” J. Biomed. Mater. Res. A, 77(1), pp. 97–102. [CrossRef] [PubMed]
ASTM Standard F756-08 A., 2013, “Standard Practice for Assessment of Hemolytic Properties of Materials,” ASTM International, West Conshohocken, PA, pp. 1–5.
ISO 10993-5 I., 2009, “Biological Evaluation of Medical Devices—Part 5: Tests for in Vitro Cytotoxicity,” ISO/TC 194, Geneva, Switzerland.
ASTM Standard G5-14, 2014, “Standard Reference Test Method for Making Potentiodynamic Anodic Polarization Measurements,” ASTM International, West Conshohocken, PA.
EPA Method 200.7, 1994, “Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Spectrometry,” U.S. Environmental Protection Agency, Cincinnati, OH.
Visser, K. R., 1989, “Electric Conductivity of Stationary and Flowing Human Blood at Low Frequencies,” IEEE Engineering in Medicine and Biology Society 11th Annual International Conference, pp. 1540–1542.
McMahon, R. E., Ma, J., Verkhoturov, S. V., Munoz-Pinto, D., Karaman, I., Rubitschek, F., Maier, H. J., and Hahn, M. S., 2012, “A Comparative Study of the Cytotoxicity and Corrosion Resistance of Nickel–Titanium and Titanium–Niobium Shape Memory Alloys,” Acta Biomater., 8(7), pp. 2863–2870. [CrossRef] [PubMed]
Satoh, G., 2013, Modification and Integration of Shape Memory Alloys Through Thermal Treatments and Dissimilar Metal Joining, Ph.D. thesis, Columbia University, New York.
Crone, W. C., Yahya, A. N., and Perepezko, J. H., 2001, “Influence of Grain Refinement on Superelasticty in NiTi,” Proceedings of the SEM Annual Conference on Experimental Mechanics, Portland, OR, pp. 510–513.
Ralston, K. D., Birbilis, N., and Davies, C. H. J., 2010, “Revealing the Relationship Between Grain Size and Corrosion Rate of Metals,” Scr. Mater., 63(12), pp. 1201–1204. [CrossRef]
Shih, C. C., Lin, S. J., Chung, K. H., Chen, Y. L., and Su, Y. Y., 2000, “Increased Corrosion Resistance of Stent Materials by Converting Current Surface Film of Polycrystalline Oxide into Amorphous Oxide,” J. Biomed. Mater. Res., 52(2), pp. 323–332. [CrossRef] [PubMed]
Zhang, Y., Jiang, S., Liang, Y., and Hu, L., 2013, “Simulation of Dynamic Recrystallization of NiTi Shape Memory Alloy During Hot Compression Deformation Based on Cellular Automaton,” Comput. Mater. Sci., 71, pp. 124–134. [CrossRef]
Akgun, O. V., Urgen, M., and Cakir, A. F., 1995, “The Effect of Heat Treatment on Corrosion Behavior of Laser Surface Melted 304L Stainless Steel,” Mater. Sci. Eng. A, 203(1–2), pp. 324–331. [CrossRef]
Prokofiev, E., Burow, J., Payton, E., Zarnetta, R., Frenzel, J., Gunderov, D. V., Valiev, R. Z., and Eggeler, G., 2010, “Suppression of Ni4Ti3 Precipitation by Grain Size Refinement in Ni-Rich NiTi Shape Memory Alloys,” Adv. Eng. Mater., 12(8), pp. 747–753. [CrossRef]


Grahic Jump Location
Fig. 1

Schematic diagram illustrating the autogenous laser brazing setup. The wires are rotated, while the laser simultaneously scans toward the interface, but is turned off before crossing over to the SS side. The angle θ corresponds to the apex angle of the cup/cone configuration.

Grahic Jump Location
Fig. 2

Visual description of the numerical model used for prediction of the galvanic current. Laplace's equation is solved in the electrolyte PBS. Material properties are taken into account as the relevant boundary conditions along the bottom border. The function fi(φ) is the polarization response for the respective material.

Grahic Jump Location
Fig. 3

Polarization response of metal samples in PBS solution. The solid lines indicate measurements, while the dashed lines are approximations. The more electronegative equilibrium potential of the NiTi will cause it to experience anodic effects, while the SS is cathodic. When the transition from the base materials goes through the two intermediary phases, the corrosion current gets significantly reduced. This data was used for fi(φ) in Fig. 2.

Grahic Jump Location
Fig. 4

Numerical simulation results for the distribution of the electric potential in the PBS solution. The gradient of this field gives the direction of electron flow and is denoted via the arrows. At either extreme along the bottom boundary, the potential approaches the equilibrium potential of the respective material nearby.

Grahic Jump Location
Fig. 5

Distribution of electron flow along the lower boundary of Fig. 4, corresponding to the corrosion current. The dotted lines are for a electrolytic conductivity that is only 10% that of the solid lines, causing a more nonuniform distribution.

Grahic Jump Location
Fig. 6

Total amount of nickel released from joined samples as a function of time. The two different processing parameters of low and high energy inputs have similar profiles, but are noticeably higher than the base NiTi. This NiTi has undergone a previous heat treatment; nontreated NiTi has a release profile higher than the treated samples in here in our case.

Grahic Jump Location
Fig. 7

Optical images comparing the interface regions for two different laser power levels. Both underwent a rotational speed of 3000 deg/s, (a) had a laser power of 15 W while (b) was irradiated at 13 W. The HAZ of the NiTi progresses through several regions before the material starts to bow out at the interface.

Grahic Jump Location
Fig. 8

SEM image of the outside interface for a joined sample. Roughness and nonuniformity is evident in this region, making it susceptible to effects such as pitting and crevice corrosion.

Grahic Jump Location
Fig. 9

Surface corrosion at the mixed interface region after 6 days (a) and 15 days (b) of exposure to the simulated body fluid. Both samples were joined at 17 W and 1500 deg/s. Rather uniform texture is seen in (a), but this surface becomes much rougher as corrosion proceeds, as evidenced by the sharper regions found in (b).

Grahic Jump Location
Fig. 12

EBSD phase map in a HAZ of the SS. At elevated temperatures, SS may become sensitized by precipitation of chromium along grain boundaries. This is a representative image of the whole region, and chromium precipitation was never detected. Thus, the biocompatibility of the SS is not harmed by the laser joining process.

Grahic Jump Location
Fig. 11

EBSD unique grain map in a region of NiTi far from the interface. The rather small grain size may be an effect of previous cold-working. When compared with the sizes of Fig. 10, it is clear that the thermal accumulation of the interface results in significant grain growth.

Grahic Jump Location
Fig. 10

Optical micrograph at the interface of a longitudinally sectioned sample. Distinct grains are clearly visible in the NiTi on the left hand side, with size increasing nearer to the interface. The inset shows an enlarged image near the outer edge, where the combination of stress and elevated temperatures resulted in dynamic recrystallization. This is a region that recrystallized without having reached the melting temperature.

Grahic Jump Location
Fig. 14

Hemolysis testing for two different laser processing parameters. Slightly more hemolytic properties are found in the sample irradiated with higher energy, but both are well within the biocompatible, safe zone. Error bars indicate standard error.

Grahic Jump Location
Fig. 13

Images of the border of the HAZ and base material in the NiTi, as indicated by the inset region of Fig. 1. More corrosion is evident in the lower power sample of (a) than for the higher power of (b). This is evidence that more intermetallic formation at the interface may act as an electrical resistance, effectively reducing the flow of the galvanic current.



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In