Effect of Normalizing and Hardening on Mechanical Properties of Spring

O. R. Adetunji, P. O. Aiyedun, S. O. Ismaila, M. J. Alao

Mechanical Engineering Department, College of Engineering, Federal University of Agriculture, Abeokuta, Abeokuta, Ogun State, Nigeria.

DOI: 10.4236/jmmce.2012.118074                

Abstract

This study was carried out to investigate the effect of heat treatment (Normalizing and Hardening) on the mechanical properties of springs. The springs were made from mild steel rod having a diameter of 6 mm, a total of 15 springs were made. The springs were then subjected to various heat treatment processes which included; normalizing, hardening and tempering. The heat treated springs were then subjected to various test in other to determine their mechanical properties, these included; impact toughness test, hardness test and tension test. The normalized spring had more strength, was harder and was much tougher than both the annealed and as received springs. The water quenched springs were the hardest of all the heat treated springs, were very brittle and had the lowest percentage elongation. Their strength was also lower than that of the normalized and as received springs. The water quenched and tempered springs had better mechanical properties required for spring making, they had the optimum combination of hardness, strength and toughness when compared with the other heat treated springs.

Keywords

Normalizing; Hardening; Tempering; Impact Toughness; Tension; Spring

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	W. Harris, “How Car Suspensions Work,” 2005. http://auto.howstuffworks.com/car-suspension.htm
[2]	E. T. George, “Steel Heat Treatment: Metallurgy and Technologies,” CRC Press, Boca Raton, 2006.
[3]	R. A. Higgins, “Engineering Metallurgy Hodder and Stoghton,” London, 1980.
[4]	T. D. Gillespie, “Fundamentals of Vehicle Dynamics,” Society of Automotive Engineers, New York, 2009.
[5]	T. Kadrinm, “ASM Materials Engineering Dictionary,” ASM International, 1992. www.asminternal.org
[6]	H. Loretta, “How to Make Springs,” 2000. http://home.earthlink.net/-bazillion/intro.html
[7]	J. M. Pellizzari, M. Zadra and A. Molinari, “Tribological Properties of Surface Engineered Hot Work Tool Steel for Aluminum Extrusion Dies,” Surface Engineering, Vol. 23, No. 3, 2007, pp. 165-168. doi:10.1179/174329406X150477
[8]	O. A. Fayol, C. A. Boher, R. B. Gras and F. A. Rezai-Aria, “Analysis of the Friction and Wear Behavior of Hot Work Tool Steel for Forging,” Wear, Vol. 255, No. 7-12, 1985, pp. 1444-1454.