Structure and properties of the HAZ metal of joints in low-alloy calcium-modified pipe steels

摘要

The method of dilatometric measurements has been used to plot diagrams of anisothermal decomposition of austenite for steels 13G1SU, 09G2FB and 10G2FB modified with calcium. Variations in the phase structure of low-alloyed tubular steels under the effect of a thermal welding cycle are shown. Constants of Abraham equations for polymorphic transformations have been determined and parameters of an empiric equation relating impact toughness values to the phase composition of the HAZ metal have been estmated. It has been established that the cooling rate within a range of 600...500℃ for steels 13G1SU, 09G2FB and 10G2FB should range from 5 to 35℃/s and that under stringent requirements for the structure should range from 8,5 to 35℃/s.