Intercritical Thermomechanical Treatments of the Microalloyed Steel Products for Welded Structures

This paper shows the laboratory experiments made on several grade steels by applying some intercritical thermomechanical treatments; Two variants were used: “down-up” thermomechanical treatment with heating and rolling in the intercritical range and “up-down” thermomechanical treatment with preliminary complete austenitizing and rolling in the intercritic interval. Structural changes, as well as changes of properties revealed in the experimental variants of the intrercritical treatment, have been compared to those revealed by controlled rolling and normalization states of delivery that are recommended to flat products from these steel grades. High values of the strength characteristics and a good plasticity have been obtained. The paper presents only a part of the results obtained when applying different regimes of thermal and thermomechanical treatment within experimental researches made at laboratory and industrial scale, on thick plates of different thicknesses and qualities of the weldable steels