Investigation in Structure of Fusion Zone of Welded Joint of High-Strength Steel with Austenite Weld

Peculiarities of phase-structural composition of the zone of thermal influence for high-strength steel that had been welded by electrodes with austenite structure were studied. Such steels are inclined to formation of cracks as a consequence of action of thermal cycle of welding. The greatest heterogeneity emerges in the region of transition from the main metal to the weld, i.e. near-boundary zone of fusion. For determining the dimensions of this hear-boundary zone, the following determining factors should be taken into account: chemical compositions of the metals joined, intensity of diffusion processes of weld pool and adjacent regions of main metal, that was in solid-liquid state. Therefore, for identification of such a region, methods of X-ray microanalysis are mainly used (X-ray spectrometry). Taking into account small dimensions of the fusion zone, for its study we used method of contact local thermoelectromotive force. It is based on the effect of emergence of thermoelectromotive force at the instant of contact of a heated rod of a thermometer probe with investigated surface. For better identification of characteristics of the near-boundary region, a combination of this method with measuring the microhard zone of thermal influence of the welded joint was used. It is shown that it is possible to take into account different nature of formation of regions of incomplete fusion of main metal and that of hear-boundary region, different chemical compositions, properties and peculiarities of formation of structure in this zone. The verification of the results obtained was carried out by means of X-ray microanalysis.