Specimens of Zn electroplated cold-rolled steel plate have been exposed for approximately 6 years.
Nucleation and growth of Zn whiskers on specimens were observed visually, and the number of days before whiskers were detected was obtained.
Micro internal stress of Zn electroplate were measured by the Hall plot method using an X-ray diffractometer. The macro internal stress were measured by X-rays and the bending strain method. These results were compared with the number of days before whiskers were detected. A corelation was found between the number of days before whiskers were detected and the macro internal stress measured by the bending strain method.
The number and length of whiskers were counted and measured, and then the rate of short circuit caused by whisker was calculated.
As a result it was found that the rate of short circuit by whisker growth was c.a. 9 fit.