Capacitor discharge welding (CDW) is a rapid solidification joining process under
the influence of one-dimensional thermal gradients. Although CDW is useful for joining
small parts and dissimilar metals, CD welded joints have a large variability in weld
strength. CDW is not widely accepted because of a lack of automated process control.
Studying the sources of variability in the CDW process can guide the automation of
CDW. Therefore, the objectives of this study were to investigate sources of variability
that affect weld strength and to generate a model to predict the weld strength variability
in CDW. The source of variability was investigated by using screening experiments. Four
different materials, stainless steel, Nitronic 50 Steel, copper, and low oxygen copper
(C101), were selected to represent various levels of thermal conductivity and absorbed
gas content. Thermal conductivity, percentage of gas content absorbed, diameter, and
welding time were treated as the independent variables while the dependent variables
were the standard deviation of CD weld strength as a percentage of base material strength
and the mean of CD weld strength as a percentage of base material strength. A screening
experiment and a statistical analysis of the data were used to develop a predictive model
of the weld strength variability in CDW. Electron photomicrographs of weld fracture surfaces and dynamic current and resistance curves for each welding cycle were used to support conclusions from the statistical analysis. Conclusions of this study are that thermal conductivity and absorbed gas content do have a significant influence on weld strength variability in CDW. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33579 |
| Date | 05 August 1998 |
| Creators | Benjarattananon, Jukchai |
| Contributors | Paul, Brian K. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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