search for


Effect of Shot Peening on Microstructural Evolution of 500-7 Ductile Cast Iron
Applied Microscopy 2018;48:73-80
Published online September 30, 2018
© 2018 Korean Society of Microscopy.

Yubing Zhang, and Keesam Shin*

School of Advanced Materials and Engineering, Changwon National University, Changwon 51140, Korea
Correspondence to: *Shin K,, Tel: +82-55-213-3696, Fax: +82-55-261-7017, E-mail:
Received July 19, 2018; Revised August 27, 2018; Accepted August 28, 2018.
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Ductile cast iron is widely used for many automotive components due to its high wear resistance and fatigue resistance in addition to the low cost of fabrication. The improvement of wear resistance and fatigue properties is key to the life time extension and performance increase of the automobile parts. Surface nanocrystallization is a very efficient way of improving the performance of materials including the wear- and fatigue-resistance. Shot peening treatment, as one of the popular and economic surface modification methods, has been widely applied to various materials. In this study, ductile cast iron specimens were ultrasonic shot peening (USP) treated for 5 to 30 min using different ball size. The microstructures were then microscopically analyzed for determination of the microstructural evolution. After the USP treatment, the hardness of pearlite and ferrite increased, in which ball size is more effective than treatment time. With USP treatment, the graphite nodule count near the surface was decreased with grain refinement. The lager balls resulted in an increased deformation, whereas the smaller balls induced more homogenously refined grains in the deformation layer. In addition, formation of nanoparticles was formed in the surface layer upon USP.

Keywords : Ductile cast iron, Shot peening, Grain refinement, Graphite, Pearlite
Fig. 1. Microhardness depth profile of ferrite and pearlite with ball size. USP, ultrasonic shot peening.
Fig. 2. Surface SEM micrographs. (A) Before; ball size 1.0 mm, (B) Ultrasonic shot peening (USP) 10, (C) USP 20, (D) USP 30; ball size 1.5 mm, (E) USP 10, (F) USP 20, (G) USP 30.
Fig. 3. Graphite area fraction of 500-7 near surface. USP, ultrasonic shot peening.
Fig. 4. Cross-sectional graphite area fraction with shot peening time and ball size. (A) 1.0 mm, (B) 1.5 mm. USP, ultrasonic shot peening.
Fig. 5. Cross-sectional EBSD analysis. (A) Before, (B) ultrasonic shot peening (USP) -1.0-5, (C) USP-1.0-10, (D) USP-1.0-15, (E) USP-1.0-20, (F) USP-1.0-25, (G) USP-1.0-30.
Fig. 6. Cross-sectional EBSD analysis. (A) Before, (B) ultrasonic shot peening (USP) -1.5-5, (C) USP-1.5-10, (D) USP-1.5-15, (E) USP-1.5-20, (F) USP-1.5-25, (G) USP-1.5-30.
Fig. 7. (A) Grain size in surface and (B) in a specific depth with ultrasonic shot peening treatment time and ball size.
Fig. 8. Surface TEM analysis. (A) Before ultrasonic shot peening (USP), USP-1.5, (B) 5 min, (C) 10 min, (D) 15 min, (E) 20 min, (F) 25 min.
Fig. 9. Surface TEM analysis. Ultrasonic shot peening (USP)-1.5 (A) 15 min, (B) 20 min, (C) 25 min, (D) 30 min.
Fig. 10. Surface TEM analysis. Ultrasonic shot peening (USP)-1.5 (A) 30 min BF, (B) 30 min DF, (C) 30 min BF, (D) 30 min DF. The circled spots in the insets are for the respective DF.
Fig. 11. Specific depth TEM analysis. Ultrasonic shot peening (USP)-1.5-30 min (A) BF, (B) DF, and 200 μm deep (C) BF.
Fig. 12. Cross-sectional TEM analysis. Ultrasonic shot peening (USP)-1.5-30 min.

Original specimen composition and mechanical property

ISO Composition (wt. %) Mechanical property

C Si Mn P S Ni Bal. R (MPa) ɛ (%) Hardness (HV)
1083 500-7 ~3.75 ~2.25 ~0.45 0.06 <0.06 <0.02 Fe 500 7 ~200

Ultrasonic shot peening (USP) treatment parameters (amplitude, 70 μm; frequency, 20 kHz)

Specimen Treatment time (min)
Ball size: 1.0 mm
 500-7 0
 USP-1.0-5 5
 USP-1.0-10 10
 USP-1.0-15 15
 USP-1.0-20 20
 USP-1.0-25 25
 USP-1.0-30 30
Ball size: 1.5 mm
 USP-1.5-5 5
 USP-1.5-10 10
 USP-1.5-15 15
 USP-1.5-20 20
 USP-1.5-25 25
 USP-1.5-30 30

  1. Bang, CW, Seol, JB, Yang, YS, and Park, CG (2015). Atomically resolved cementite dissolution governed by the strain state in pearlite steel wires. Scr Mater. 108, 151-155.
  2. Berto, F, Ferro, P, and Salavati, H (2017). Fatigue strength of sharp V-notched specimens made of ductile cast iron. Eng Fail Anal. 82, 308-314.
  3. Fang, F, Zhao, Y, Liu, P, Zhou, L, Hu, XJ, Zhou, X, and Xie, ZH (2014). Deformation of cementite in cold drawn pearlitic steel wire. Mater Sci Eng. 608, 11-15.
  4. Ganapathy, T, and Bhoopathy, T (2015). Experimental investigation of the residual stress and calculate average fatigue life and improved resistance to stress corrosion cracking on aluminum alloy 7075-T6 plates by using various shots through shot peening process. Int J Mod Eng Res. 5, 9-14.
  5. He, Y, Li, K, Cho, IS, Lee, CS, Park, IG, Song, JI, and Shin, K (2015). Microstructural characterization of SS304 upon various shot peening treatments. Appl Microsc. 45, 155-169.
  6. Khameneh, MJ, and Azadi, M (2018). Evaluation of high-cycle bending fatigue and fracture behaviors in EN-GJS700-2 ductile cast iron of crankshafts. Eng Fail Anal. 85, 189-200.
  7. Kumar, H, Singh, S, and Kumar, P (2013). Modified shot peening process. Int J Eng Sci Emerg Technol. 5, 12-19.
  8. Luo, X, and Chung, D (2000). Vibration damping using flexible graphite. Carbon. 38, 1499-1524.
  9. Marsh, KJ (1993). Shot Peening: Techniques and Applications. Warley: EMAS
  10. Nam, K, He, Y, and Shin, K (2018). Microstructural evolution of Super304H upon ultrasonic shot peening and subsequent annealing. J Nanosci Nanotechnol. 18, 6274-6277.
    Pubmed CrossRef
  11. Ochi, Y, Masaki, K, Matsumura, T, and Sekino, T (2001). Effect of shot-peening treatment on high cycle fatigue property of ductile cast iron. Int J Fatigue. 23, 441-448.
  12. Okabayasi, K, Saito, S, and Nakamura, F (1958). Wear resistance of spheroidal graphite cast iron: effect of the amount of ferrite in the matrix on wear resistance. Japan Foundarymen’s Soc. 30, 866-873.
  13. Pan, R, Ren, R, Chen, C, and Zhao, X (2017). Formation of nanocrystalline structure in pearlitic steels by dry sliding wear. Mater Charact. 132, 397-404.
  14. Radzikowska, JM (2004). Metallography and microstructures of cast iron. Metallogr Microstructur. 9, 565-587.
  15. Shukla, P, Swanson, P, and Page, C (2013). Laser shock peening and mechanical shot peening processes applicable for the surface treatment of technical grade ceramics: a review. Proc MechE Part B: J Eng Manuf. 228, 639-652.
  16. Teshima, T, Kosaka, M, Ushioda, K, Koga, N, and Nakada, N (2017). Local cementite cracking induced by heterogeneous plastic deformation in lamellar pearlite. Mater Sci Eng: A. 679, 223-229.
  17. Wang, Y, Fang, F, Wang, L, Jiang, JQ, and Yang, H (2010). Microstructure evolution of cementite in cold drawn pearlitic steel wires. Trans Mater Heat Treat. 5, 022.
  18. Watanabe, Y, Hattori, K, Handa, M, Hasegawa, N, Tokaji, K, Ikeda, M, and Duchazeaubeneix, JM (2002). Effect of ultrasonic shot peening on fatigue strength of high strength steel. 10th International Conference on Shot Peening (ICSP10). Tokyo: Electronics Inc., pp. 305-310
  19. William, G (1992). Materials for Tribology. Netherland: Elsevier
  20. Yu, H, Dong, J, Yoo, D, and Shin, K (2009). Microstructural characterization of SS304 upon various shot peening treatments. J Korean Phys Soc. 54, 1161-1166.

December 2018, 48 (4)
Full Text(PDF) Free

Social Network Service

Cited By Articles
  • CrossRef (0)

Author ORCID Information

Funding Information
  • Science Central
  • CrossMark
  • Crossref TDM