Abstract: A process for determining a temperature at a spot weld formed between two parts being made of at least one first metal by at least one electrode being made of a second metal and being in contact with one of the parts, includes determining a first measurement value for a thermoelectric voltage between the electrode and the parts prior to forming the spot weld. A second measurement value is determined for a thermoelectric voltage between the electrode and the parts after forming the spot weld. The temperature is determined by taking both measurement values into account. A device for determining a temperature at the spot weld includes at least one volt meter for ascertaining a thermoelectric voltage between the electrode and the parts, corresponding to a temperature. A control unit records at least one first measurement value for the thermoelectric voltage prior to formation of a spot weld and at least one second measurement value for the thermoelectric voltage after the formation of the spot weld.

Abstract: A method and an apparatus for ascertaining an evaluation time interval for assessing the quality of a spot weld based on a course of a temperature at the weld, call for a course of a variable which is unequivocally associated with the temperature to be ascertained for a multiplicity of reference spot welds of differing quality, and for the courses of the variable to be compared with each other. A time interval which is determined from the comparison of the courses is used as the evaluation time interval, and the courses are significantly different from each other and have a sequence which corresponds to a sequence of the qualities of the associated reference spot welds. An allocation of the quality of any spot weld can be carried out simply and precisely by using values of the temperature-dependent variable within the evaluation time interval.