In this study, the effect of buttering process and the role of silicon content in three dual-phase steels with different silicon content on the microstructural evolutions of the weld zone and heat-affected zone in the dissimilar joint of dual-phase steels to austenitic stainless steel in the two-pass GTAW process were investigated. The results showed that due to the different thermal cycles experienced during welding, the joint microstructure consists of five distinct regions of the base metal, subcritical, intercritical, supercritical heat-affected zones, and the melting zone. Each of these five zones undergoes different phase transformations under the influence of the maximum temperature experienced and the cooling rate. Metallographic studies showed that in the HAZ zone of dual-phase steels, phases such as martensite, bainite, grain boundary ferrite, Widmanstatten ferrite, amorphous ferrite and polymorphic ferrite are formed. The type, morphology and distribution of which are a direct function of the welding thermal cycle. The study of the effect of silicon content showed that increasing the amount of this element in the base steel leads to a noticeable change in the microstructure of the heat affected zone; in such a way that with increasing silicon, the tendency to form ferrite and bainite increases and, on the contrary, the volume fraction of martensite decreases. The microstructure of the melting zone was investigated and it was found that in multi-pass welds, delta ferrite was observed in continuous, semi-continuous and isolated forms under the influence of successive thermal cycles. The results of EDX analysis showed that increasing the chromium concentration in the melted zone plays an effective role in increasing the microhardness of the weld metal. The results were discussed in terms of the dilution phenomenon.