Verfahren zur Bewertung von Schweissverbindungen

The description relates to a process for assessing resistance welding joints using an ultrasonic transmitter which applies ultrasonic waves to the welding area, and an ultrasonic receiver. The process according to the invention comprises the following steps: - during the welding process, the velocity c<-2 of the ultrasonic waves in the welding area is determined as a function of time t, - from the determined sound velocity c<-2 (t) in the welding area, the temperature T(t) of the welding area is determined in comparison with a previously determined temperature dependence of the sound velocity c<-2 (t) in the weld metal as a function of the welding duration, - from the temperature curve T(t) in the welding area, the melting time point T<-s of the welding metal is determined by comparison with the melting temperature of the welding metal T<-s, and - from the melting time point t<-s, the expected welding nugget diameter <diameter> expected at the end of the welding period t is calculated from the melting time point t<-s during the welding process.