Cracking Phenomenon in Spot Welded Joints of Austenitic Stainless Steel

Ahmed M. Al-Mukhtar, Qasim M. Doos

Faculty of Geosciences and Geoengineering, Technische Universit?t Bergakademie Freiberg, Freiberg, Germany; Al-Khawirizmie College of Engineering, Baghdad University, Baghdad, Iraq.
Mechanical Engineering Department, College of Engineering, Baghdad University, Baghdad, Iraq.

DOI: 10.4236/msa.2013.410081                

Abstract

The spot welds nugget cracking of austenitic stainless steel at temperatures between 700°C - 1010°C was investigated. Traditionally, the cracks have been observed around the spot nugget in welded temperature. Actually, these cracks are developed due to incomplete melting and inappropriate electrode pressure, which causes an expulsion of molten metal. These cracks start to grow and cause either the interface or plug fracture according to the loading type. In this work, the micro-cracks in the weld nugget were indicated for this type of steel at elevated temperature. Cracks appear in a certain range of temperature; about 700°C - 750°C. The cracks like defect and cavitations were presented. According to the fracture mechanics point of view, these cracks reduce the mechanical strength. Therefore, these cracks have to be taken into account with a certain precaution. Moreover, considering the working temperature and reducing the element may develop ferrite particles.

Keywords

Austenitic Stainless Steel; Cracking; Ferrite Contents; Fatigue Cracks; Spot Welded Joints; Weld Nugget; Weld Notches

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	M. Vural and A. Akkus, “On the Resistance Spot Weldability of Galvanized Interstitial Free Steel Sheets with Austenitic Stainless Steel Sheets,” Journal of Materials Processing Technology, Vol. 153-154, 2004, pp. 1-6.
[2]	G. Mukhopadhyay, S. Bhattacharya and K. K. Ray, “Strength Assessment of Spot-Welded Sheets of Interstitial Free Steels,” Journal of Materials Processing Technology, Vol. 209, No. 4, 2009, pp. 1995-2007.
[3]	H. Yu, S. Yang, H. Y. Kang, H. G. Kim and K. S. Kim. “Fatigue Life Analysis of Spot Weldment of Cold Rolled and High Strength Steel Using FEM,” Transaction of the Korean Society of Machine Tool Engineers, Vol. 17, No. 5, 2008, pp. 58-63.
[4]	M. M. Rahman, “Fatigue Life Prediction of Spot-Welded Structures: A Finite Element Analysis Approach,” European Journal of Scientific Research, Vol. 22, No. 3, 2008, pp. 444-456.
[5]	J. Senkara and H. Zhang, “Cracking in Spot Welding Aluminum Alloy AA5754,” Welding Journal—New York, Vol. 79, No. 7, 2000, pp. 194s-201s.
[6]	J. C. Lippold, E. F. Nippes and W. F. Savage, “An Investigation of Hot Cracking in 5083-0 Aluminum Alloy Weldments,” Welding Journal, Vol. 56, No. 6, 1977, pp. 171s-178s.
[7]	S. E. Mirsalehi and A. H. Kokabi, “Fatigue Life Estimation of Spot Welds Using a Crack Propagation-Based Method with Consideration of Residual Stresses Effect,” Materials Science and Engineering: A, Vol. 527, No. 23, 2010, pp. 6359-6363. http://dx.doi.org/10.1016/j.msea.2010.06.070
[8]	S. Lin, J. Pan, P. Wung and J. Chiang, “A Fatigue Crack Growth Model for Spot Welds under Cyclic Loading Conditions,” International Journal of Fatigue, Vol. 28, No. 7, 2006, pp. 792-803. http://dx.doi.org/10.1016/j.ijfatigue.2005.08.003
[9]	A. M. Al-Mukhtar, H. Biermann, P. Huebner and S. Henkel, “Comparison of the Stress Intensity Factor of LoadCarrying Cruciform Welded Joints with Different Geometries,” Journal of Materials Engineering and Performance, Vol. 19, No. 6, 2010, pp. 802-809. http://dx.doi.org/10.1007/s11665-009-9552-1
[10]	A. M. Al-Mukhtar, H. Biermann, P. Huebner and S. Henkel, “Determination of Some Parameters for Fatigue Life in Welded Joints Using Fracture Mechanics Method,” Journal of Materials Engineering and Performance, Vol. 19, No. 9, 2010, pp. 1225-1234. http://dx.doi.org/10.1007/s11665-010-9621-5
[11]	A. M. Al-Mukhtar, “Spot Welding Efficiency and Its Effect on Structural Strength of Gas Generator and Its Performance,” M.Sc. Thesis, Baghdad University, Baghdad, 2002.
[12]	“Handbook, Welding,” American Welding Society, New York, 1978.
[13]	American Society for Metals, “Metal Handbook: Welding and Brazing,” 8th Edition, ASM International, Materials Park, 1971.
[14]	A. I. Pugachev, N. B. Demkin and V. I. Ryazantsev, “Dimensions of Initial Contact in Spot Welding of Light Alloys,” Welding Research Abroad, April 1969, pp. 72-76.
[15]	A. M. Al-Mukhtar, H. Biermann, P. Huebner and S. Henkel, “The Effect of Weld Profile Geometries of Butt Weld Joints on Fatigue Life under Cyclic Tensile Loading,” Journal of Materials Engineering and Performance, Vol. 20, No. 8, 2011, pp. 1385-1391. http://dx.doi.org/10.1007/s11665-010-9775-1
[16]	J. F. Lancaster, “The Metallurgy of Welding, Brazing and Soldering,” George Alden and Unwin LTD., London, 1970.
[17]	M. Kamaraj and V. M. Radhakrishnan, “High Temperature Crack Growth in Austenitic Weld Metal,” Engineering Fracture Mechanics, Vol. 33, No. 5, 1989, pp. 801-811.
[18]	Q. Doos and A. M. Al-Mukhtar, “Static Strength Behavior of Austenitic Stainless Steel Sheet,” Journal of Engineering College, Baghdad University, Vol. 10, No. 2, 2004.
[19]	A. M. Al-Mukhtar, “Investigation of the Thickness Effect on the Fatigue Strength Calculation,” Journal of Failure Analysis and Prevention, Vol. 13, No. 1, 2013, pp. 63-71. http://dx.doi.org/10.1007/s11668-012-9629-2