Fatigue Strength Improvement of Low Carbon Steel Resistance Spot Welds by the StressWave™ Process

2005 ◽  
Author(s):  
B. D. Flinn ◽  
R. Spitsen ◽  
D. Kim ◽  
T. Nam ◽  
E. T. Easterbrook
2005 ◽  
Vol 127 (4) ◽  
pp. 718-723 ◽  
Author(s):  
R. Spitsen ◽  
D. Kim ◽  
B. Flinn ◽  
M. Ramulu ◽  
E. T. Easterbrook

The investigation on the use of a post-weld cold working process to improve fatigue strength of low carbon steel resistance spot welds is presented. The cold working process generates uniform and consistent large zones of compressive residual stresses in resistance spot-welded low carbon steel structures using a specially designed indentation device. The effect of the indentation process parameters on the mechanical properties of the resistance spot weld was investigated. Comparisons of the mechanical properties and qualitative results between the as-resistance spot-welded specimens and the post-weld cold worked resistance spot-welded specimens have been made in this investigation. Fatigue testing was also conducted to evaluate the effect of post-weld cold working process on the fatigue characteristics of resistance spot welds. Results showed that a significant improvement in the fatigue strength has been achieved through the post-weld cold working process.


2014 ◽  
Vol 875-877 ◽  
pp. 1499-1502 ◽  
Author(s):  
Ladislav Kolařík ◽  
Miroslav Sahul ◽  
Marie Kolaříková ◽  
Martin Sahul ◽  
Milan Turňa

The contribution deals with resistance spot welding of low carbon steel to austenitic CrNi stainless steel. The thickness of welded dissimilar steels was 2 mm. DeltaSpot welding gun with process tape was utilized for welding of the above-mentioned combination of steels. Resistance spot welds were produced under different welding currents. The welding currents used were 7 kA, 7.5 kA and 8 kA, respectively. Optical microscopy, microhardness measurement across the weld joint and EDX analysis across the weld joint interface were used to evaluate the quality of resistance spot welds of dissimilar steels.


Author(s):  
R. Spitsen ◽  
D. Kim ◽  
B. Flinn ◽  
M. Ramulu ◽  
E. T. Easterbrook

The investigation on the use of a post-weld cold working process to improve fatigue strength of low carbon steel resistance spot welds is presented. The cold working process generates uniform and consistent large zones of compressive residual stresses in resistance spot-welded low carbon steel structures using a specially designed indentation device. The effect of the indentation process parameters on the mechanical properties of the resistance spot-weld was investigated. Comparisons of the mechanical properties and qualitative results between the as-resistance spot-welded specimens and the post-weld cold worked resistance spot-welded specimens have been made in this investigation. Fatigue testing was also conducted to evaluate the effect of post-weld cold working process on the fatigue characteristics of resistance spot welds. Preliminary results showed that a significant improvement in the fatigue endurance limit has been achieved through the post-weld cold working process.


2009 ◽  
Vol 83-86 ◽  
pp. 1205-1211 ◽  
Author(s):  
Majid Pouranvari ◽  
Pirooz Marashi

Resistance spot welding is the dominant process for joining sheet metals in automotive industry. Even-thickness combinations are rarely used in practice; therefore, there is clearly a practical need for failure behaviour investigation of uneven-thickness resistance spot welds. The aim of this paper is to investigate and analyze the failure mode and failure mechanism of dissimilar thickness low carbon steel resistance spot welds during tensile-shear overload test. Microstructural investigations, microhardness tests and tensile-shear tests were conducted. Mechanical properties of the joint were described in terms of peak load, energy absorption and failure mode. It was concluded that weld nugget size and the strength of the thinner base metal are the controlling factors of the peak load and energy absorption of dissimilar thickness spot welds.


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