Vliv doválcovací a navíjecí teploty na mikrostrukturu a mechanické vlastnosti pásu z oceli X70

Abstract

The diploma thesis deals with the influence of finish rolling and coiling temperatures on the structural and mechanical properties of a rolled strip intended for welded pipes made of steel grade X70, microalloyed with niobium, vanadium and titanium. Based on simulations of the process of temperature-controlled rolling and accelerated cooling on the laboratory rolling mill, the results of structural analyzes and tensile tests, a combination of a finish rolling temperature of 800 ° C and a coiling temperature of approx. 600 ° C – 620 ° C was proposed as optimal. In laboratory conditions, the required mechanical properties of the strip were achieved: ductility min. 18%, yield stress min. 545 MPa and ultimate tensile strength in the range of 600 MPa – 760 MPa.