Hardness and Impact Toughness of Niobium Alloyed Austempered Ductile Iron

Abstract:

The effect of different austempering holding times on the hardness and impact toughness of 0.254% niobium alloyed austempered ductile iron was investigated in this study. Molten ductile iron was prepared in an induction furnace with capacity of 60kg. Samples with dimension of 300m x Ø25mm in form of Y block double cylinder was constituted and solidified samples were then machined in accordance to ASTM E23 for impact test specimens. Samples were ground and polished before Rockwell hardness test was conducted. Austempering heat treatment process with austenitizing temperature of 900°C for 1 hour and austempering temperature of 350°C for 1 hour, 2 hours and 3 hour holding times were then carried out. The results from this research indicated that austempering the sample for 1 hour resulted in significant improvement of the impact toughness values but increasing the austempering holding time deficiently reduced the values. On the contrary, the hardness of niobium alloyed austempered ductile iron continues to increase with respect to longer austempering holding times.

• Periodical: Advanced Materials Research (Volumes 418-420)
• Pages: 1768-1771
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.418-420.1768
• Online since: December 2011
• Authors: Bulan Abdullah, Siti Khadijah Alias, Ahmed Jaffar, Rashiddy Wong Freddawati, A. Ramli
• Keywords: Austempered Ductile Iron, Hardness, Impact Toughness, Niobium

References

[1] Ductile iron data for design engineers (1992). Rio Tinto Iron and Titanium Inc., Canada

[2] B. Abdullah, A. Jaffar, S.K. Alias, R. Jaafar, A. Ramli and A.Faitullah. Proceedings of SPIE: The International Society for Optical Engineering 7522 (2010) art. No. 7522450

[3] B. Abdullah, A. Jaffar, S.K. Alias, A. Ramli and M.F Izham. Proceedings of SPIE : The International Society for Optical Engineering 7522 (2010) art. No. 7522400

[4] B. Abdullah, A. Jaffar, S.K. Alias, A. Ramli and A. Rashid. Proceedings in 2010 International Conference on Mechanical and Electrical Technology, art. no. 5598431 (2010) pp.610-614

[5] P.W Shelton and A.A. Bonner.Journal of Material Processing Tech, vol 173 (2006) p.269–274

[6] A.R. Kiani-Rashid. Journal of Alloys and Compounds, vol 470 (2009) p.323–327

[7] M.C. Cakir and YIsik. Mater and Dsgn vol 29 (2008) p.937–942

[8] J. Zimba, D.J. Simbi and E. Navara Cem. & Con Com vol 25 (2003) p.643–649.

[9] X. Zhi, J. Xing, Y. Gao,H. Fu, J. Peng, B. Xiao. Materials Science and Engineering, A vol. 487 (2008) p.171–179.

[10] M.A Islam, M.M Ali Bepari. Journal of Materials Processing Technology vol.74 (1998) p.183–189.

[11] B. Abdullah. Thesis submitted to Universiti Teknologi MARA, Malaysia. (2011)

[12] A.H. Elsayed et.al, Mtrl and Dsgn vol 30 (2009) p.1866–1877

[13] O. Eric, L. Sidjanin, Z. Miskovic, S. Zec. Mater Lttrs vol.58 (2004) p.2707– 2711