In this paper mechanical aspects of cracking during single- and multi-spot welding of AA5754 was investigated by both experimental and analytical approaches. The impact of mechanical loading on crack initiation and propagation was studied with the consideration of various process parameters including the loading imposed by electrodes, the formation of liquid nugget, and constraining factors during and after welding. Tensile properties of AA5754 and their dependence on the temperature were tested at room and up to solidus temperatures, in order to provide a reference of cracking stress. Thermal-mechanical analysis was conducted based on the temperature field around the nugget and the state of stress encountered during welding. This analysis revealed that tensile stress might build up in the vicinity of the nugget during cooling, as explained in the experimental observation. General guidelines for suppressing cracking were proposed, i.e., to provide sufficient constraint around the weld spot during and after welding.

Issue Section:
Technical Papers
Keywords:
resistance welding, cracks, tensile strength, thermal analysis, mechanical variables control
Topics:
Cracking (Materials), Fracture (Materials), Fracture (Process), Welding, Electrodes, Temperature
1.
Warren
,
A. S.
,
1991
, “
The Future for Increased Use of Aluminum in Cars
,”
Aluminum
,
67
(
11
), pp.
1078
–
1080
.
2.
Osterman, F., 1993, Aluminum Materials Technology for Automobile Construction, Mechanical Engineering Publications Ltd, London.
3.
Irving
,
B.
,
1995
, “
Building Tomorrow’s Automobiles
,”
Weld. J. (Miami)
,
74
(
8
), pp.
29
–
34
.
4.
Welding Handbook Volume 3: Materials and Applications—Part 1, 1996, 8th Edition, AWS, Miami, FL, pp. 18–19.
5.
Anik
,
S.
, and
Dorn
,
L.
,
1991
, “
Metal Physical Processes During Welding—Weldability of Aluminum Alloys
,”
Welding Research Abroad
,
XXXVII
, pp.
41
–
44
.
6.
Pellini
,
W. S.
,
1952
, “
Strain Theory of Hot Tearing
,”
Foundry Trade J.
80
, pp.
125
–
133
.
7.
Borland
,
J. C.
,
1961
, “
Suggested Explanation of Hot Cracking in Mild and Low Alloy Steel Welds
,”
British Welding Journal
,
8
, pp.
526
–
540
.
8.
Prokhorov
,
N. N.
,
1968
, “
Theorie und Verfahren zum Bestimmen der Technologischen Festigkeit von Metallen beim Schweissen
,”
Schweisstechnik
,
19
, pp.
8
–
11
.
9.
Watanabe, G., and Tachikawa, H., 1995, “Behaviour of Cracking Formed in Aluminum Alloy Sheets on Spot Welding,” 48th Annual Assembly of IIW, Stockholm, IIW Doc. No III-1041-95.
10.
Michie, K. J., and Renaud, S. T., 1996, “Aluminum Resistance Spot Welding: How Weld Defects Affect Joint Integrity,” Proc. AWS Sheet Metal Welding Conference VII, Detroit, MI, Paper No. B5.
11.
Thornton
,
P. H.
,
Krause
,
A. R.
, and
Davies
,
R. G.
,
1996
, “
The Aluminum Spot Weld
,”
Weld. J. (Miami)
,
75
(
3
), pp.
101-s to 108-s
101-s to 108-s
.
12.
Senkara
,
J.
, and
Zhang
,
H.
,
2000
, “
Cracking in Multi-Spot Welding Aluminum Alloy AA5754
,”
Weld. J. (Miami)
,
79
(
7
), pp.
194-s to 201-s
194-s to 201-s
.
13.
Resistance Welding Manual, 1946, the Resistance Welder Manufacturers’ Association.
14.
Automotive Sheet Specification, 1994, Alcan Rolled Products Company, Feb.
15.
Binary Alloy Phase Diagrams, 1990, Massalski, T. B., ed., 2nd Ed., ASM, Materials Park, OH.
16.
Senkara, J., Zhang, H., and Hu, S. J., 2001, “Expulsion Prediction in Resistance Spot Welding,” Weld. J. (Miami), in press.
17.
Aluminum: Properties and Physical Metallurgy, 1984, Hatch, J. E., ed., ASM, Metals Park, OH.
18.
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.
19.
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
.
20.
Prokhorov
,
N. N.
,
1968
, “
Theorie und Verfahren zum Bestimmen der Technologischen Festigkeit von Metallen beim Schweissen
,”
Schweisstechnik
,
19
, pp.
8
–
11
.
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