Journal of South China University of Technology (Natural Science Edition) ›› 2014, Vol. 42 ›› Issue (9): 1-6.doi: 10.3969/j.issn.1000-565X.2014.09.001

• Mechanical Engineering •     Next Articles

Burnishing-Induced Ultra-Fine Grained Pure Iron Surface Layer and Its Corrosion Resistance

Li Ning Xia Wei Zhao Jing Li Feng-lei   

  1. School of Mechanical and Automotive Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China
  • Received:2014-04-17 Revised:2014-06-03 Online:2014-09-25 Published:2014-08-01
  • Contact: 李宁(1985-)，男，博士生，主要从事滚压纳米化性能研究． E-mail:l.ning12@mail.scut.edu.cn
  • About author:李宁(1985-)，男，博士生，主要从事滚压纳米化性能研究．
  • Supported by:

    国家自然科学基金资助项目( 51375174) ; 广东省自然科学基金杰出青年基金资助项目( S2013050014163)

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Abstract:

In the investigation,by means of a new surface self-nanocrystallization technique named SPRB ( SeverePlasticity Roller Burnishing) ,a gradient ultra-fine grain ( UFG) surface layer of a minimum grain size of about 300nmwas fabricated on pure iron.Then,the microstructure and the corrosion behavior of UFG surface layer wereanalyzed by means of TEM,XRD,SEM and electrochemical methods.The results show that ( 1) the outermost layerhardness of UFG iron is improved by more than 1.6 times in comparison with that of coarse grain ( CG) iron; ( 2) astrongly basal-textured grain orientation forms on the UFG surface and its micro strain is ( 0.313 ±0.017) %; ( 3) in 3.5% NaCl solution,the open circuit corrosion potential of UFG Fe is 24mV more than that of CG Fe in the positivedirection,and the corrosion current density decreases from 2.371 × 10－5 A/cm2 of CG Fe to 7.547 × 10－8 A/cm2 of UFG Fe; ( 4) in 6% FeCl3 solution,the pitting rate of UFG Fe is about half as much as that of CG Fe; ( 5) thecorrosion resistance of UFG Fe is remarkably improved in comparison with that of CG Fe; and ( 6) the corrosion resistanceimprovement of UFG Fe is attributed to the surface grain refinement and the formation of the strongly basaltexturedgrain orientation.

Key words: burnishing, ultra-fine grain, pure iron, electrochemical corrosion