Thermophysical Properties of High-Strength Low-Alloyed Pipe Steel

Thermo-mechanical controlled processing (TMCP) of low-carbon low-alloy pipe steels is used to attain the required level of mechanical properties in rolled plates designed for pipe production, thereby ensuring the operational stability and reliability of trunk pipelines. The TMCP involves the hot deformation of austenite followed by accelerated cooling, during which the γ → α transformation occurs. The technological capabilities of contemporary plate mills permit developing and implementing information systems for the control of steel structure and, consequently, its properties. The reliability and accuracy of such systems can be enhanced by using the correct thermophysical parameters of steels. In the present work the critical temperatures, temperature dependences of heat capacities of main phases, and thermal effects of phase transformations in specimens of 05G2MB (wt % ~ 0.05 C; ≤ 2.0 Mn; ~ 0.2 Mo; ~ 0.05 Nb) high-strength low-alloyed pipe steel have been determined employing differential scanning calorimetry method, dilatometric analysis, and calculations using Thermo-Calc software. It has been demonstrated that the thermal effect of magnetic transformation exhibits a markedly greater value than that of polymorphic phase transformation.