Measurement of permanent deformation in surfacing and spray welding

The authors are of the opinion that an understanding of the thermal and displacement processes represents two highly practical quality indicators in these two welding processes. They can be measured by means of video recordings where the movement of places marked by Vickers hardness pyramid markings and their temperature are recorded by a thermovision camcorder. The evaluation requires the following: digitalisation of the recorded visual information, plotting the measured data against welding time, their interactive correction, averaging the measurement curves of three or five identical places, then equalising the averaged curves so that they can be numerically differentiated at least three times in the time interval under examination. Our experience shows that Rykalin's thermal wave theory is prevalent both in the surfacing and in the spray welding process, which means that it is possible to switch over from the time function to the spatial co-ordinate function. The paper presents the derivatives of the thermal and displacement processes, those according to the derived spatial co-ordinates, which facilitates a comparison between single-layer surfacing and spray welding with induction fusing.