QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY
Print ISSN : 0288-4771
Analysis of Electric Resistance of Bond Interface in Diffusion Welding by Constriction Resistance
Toshio EnjoKenji IkeuchiNaofumi AkikawaTsukasa Okazaki
Author information
JOURNALS FREE ACCESS

1987 Volume 5 Issue 2 Pages 193-200

Details
Abstract

New equations giving constriction resistance RC as a function of area SM and number density n of true contact spots have been obtained from a model experiment, and applied to the analysis of the electric resistance of the bond interface ΔR for the diffusion-welded joint of titanium. The new equations obtained are described as
RC= ρ/√n ⋅S ( √π/2 √S/√SM -1.21) ……(1)
for (SM/S)<1/4, and
RC= ρ/√πn⋅S {√ S/SM tan-1(√ S/SM -1)-0.842(1-√ SM/S )} ……(2)
for (SM/S)> 1/4, where ρ is the resistivity of base metal and S the apparent contact area. It can be seen from these equations that parameter A=(ΔR⋅S/ρ) depends only on (SM/S) and n, if ΔR=RC. Parameter A measured at temperatures from 77 K to room temperature for joints of titanium, however, decreased with a rise in the temperature of measurement, and its temperature dependence became less pronounced with the increase in welding temperature and time. On the other hand, area SM and density n were estimated from fractured surfaces of joints on the assumption that spots where grooves caused by machining of the faying surface were annihilated corresponded to true contact spots. Parameter A estimated from SM and n thus obtained using eqs. (1) and (2) was significantly smaller than that measured at 77 K and rather in good agreement with that measured at room temperature. This result indicates that not all the true contact spots observed on fractured surfaces corresponded to completely bonded spots having electrical properties identical with those of the base metal. The dependence of A on the temperature of measurement can be accounted for by a model that the bond interface consists of three characteristic spots: unbonded spot, completely bonded spot and incompletely bonded spot containing inclusions such as oxide films.

Information related to the author
© by JAPAN WELDING SOCIETY
Previous article Next article
feedback
Top