Expulsion is an important phenomenon in resistance spot welding. It involves loss of metal from the liquid nugget, which often results in the reduction of weld strength. Various models have been proposed to understand expulsion mechanisms. In these models the occurrence of expulsion is often treated as a deterministic event, and depicted by a line (boundary) in conventional lobe diagrams. In this study, statistical analysis is employed to explore expulsion with consideration of the influence of random factors. Models are built based on experimental data, and one steel and two aluminum alloys are used as examples. Expulsion probabilities are presented as a function of electrode force, welding current, and time. Analytical models and their graphical form of expression (contours and surfaces) are created to present expulsion limits under various combinations of welding parameters. This study provides not only quantitative model predictions on expulsion limits for the materials studied, but also a generic statistical methodology that can be used for analyzing expulsion in various material systems. [S1087-1357(00)00602-X]

Issue Section:
Technical Papers
Keywords:
welding, statistical analysis, joining processes
Topics:
Aluminum alloys, Statistical analysis, Steel, Welding, Electrodes, Probability
1.
Senkara, J., Zhang, H., and Hu, S. J., 2000, “Expulsion Prediction in Resistance Spot Welding,” Welding J., in press.
2.
Davies, A. C., 1993, “The Science and Practice of Welding: Volume 2—The Practice of Welding,” 10th ed., p. 210.
3.
Wu
,
K. C.
,
1977
, “
The Mechanism of Expulsion in Weldbonding of Anodized Aluminum
,”
Weld. J. (Miami)
,
56
, No.
8
, pp.
238-s–244-s
238-s–244-s
.
4.
Dickinson
,
D. W.
,
Franklin
,
J. E.
, and
Stanya
,
A.
,
1980
, “
Characterization of Spot Welding Behavior by Dynamic Electrical Parameter Monitoring
,”
Weld. J. (Miami)
,
59
, No.
6
, pp.
170-s–176-s
170-s–176-s
.
5.
Browne
,
D. J.
,
Chandler
,
H. W.
,
Evans
,
J. T.
, and
Wen
,
J.
,
1995
, “
Computer Simulation of Resistance Spot Welding in Aluminum-Part I
,”
Weld. J. (Miami)
,
74
, No.
10
, pp.
339-s–344-s
339-s–344-s
.
6.
Browne
,
D. J.
,
Chandler
,
H. W.
,
Evans
,
J. T.
,
James
,
P. S.
,
Wen
,
J.
, and
Newton
,
C. J.
,
1995
, “
Computer Simulation of Resistance Spot Welding in Aluminum-Part II
,”
Weld. J. (Miami)
,
74
, No.
12
, pp.
417-s–422-s
417-s–422-s
.
7.
Schumacher, B. W., and Soltis, M., 1988, “Getting Maximum Information from Welding Lobe Tests,” Proc. AWS Sheet Metal Welding Conference III, Detroit, Mich., Paper No. 16.
8.
Gould, J. E., Kimchi, M., Leffel, C. A., and Dickinson, D. W., 1991, “Resistance Seam Weldability of Coated Steels. Part I: Weldability Envelopes,” Edison Welding Institute Research Report, MR9112, Nov. 1991.
9.
Browne, D. J., Newton, C., and Boomer, D. R., 1995, “Optimization and Validation of a Model to Predict the Spot Weldability Parameter Lobes for Aluminum Automotive Body Sheet,” Proc. International Body Engineering Conference IBEC’95-Advanced Technologies & Processes, pp. 100–106.
10.
Kaiser
,
J. G.
,
Dunn
,
G. J.
, and
Eagar
,
T. W.
,
1982
, “
The Effect of Electrical Resistance on Nugget Formation During Spot Welding
,”
Weld. J. (Miami)
,
61
, No.
6
, pp.
167-s–174-s
167-s–174-s
.
11.
Karagoulis, M. J., 1992, “Control of Materials Processing Variables in Production Resistance Spot Welding,” Proc. AWS Sheet Metal Welding Conference V, Detroit, Mich., Paper No. B5.
12.
Zhang, H., Huang, Y., and Hu, S. J, 1996, “Nugget Growth in Spot Welding of Steel and Aluminum” Proc. AWS Sheet Metal Welding Conference VII, Detroit, MI, Paper No. B3.
13.
Gupta
,
O. P.
, and
De
,
A.
,
1998
, “
An Improved Numerical Modeling for Resistance Spot Welding Process and Its Experimental Verification
,”
ASME J. Manuf. Sci. Eng.
,
120
, pp.
246
–
251
.
14.
McCullagh, P., and Nelder, J. A., 1989, Generalized Linear Models, 2nd ed., Chapman & Hall, London, UK, pp. 21–135.
15.
Sen, A., and Srivastava, M., 1990, Regression Analysis: Theory, Methods, and Applications, Springer-Verlag, New York, pp. 234–238.
16.
S-PLUS, Version 3.4 for Sum SPARC. Copyright 1996, MathSoft, Inc.
17.
Auhl, J. R., and Patrick, E. P., 1994, “A Fresh Look at Resistance Spot Welding of Aluminum Automotive Components,” SAE Paper No. 940160.
18.
Patrick, E. P., and Spinella, D. J., 1996, “The Effects of Surface Characteristics on the Resistance Spot Weldability of Aluminum Sheet,” Proc. AWS Sheet Metal Welding Conference VII, Troy, Mich., Paper No. B4.
Copyright © 2000
 by ASME
You do not currently have access to this content.