Estudo da influência de sequências termomecânicas nas propriedades mecânicas do aço ARBL API 5l x80.

Abstract

With the need to design new steels for use in pipeline systems, the development of High Strength Low Alloy (HSLA) arose, where, among them, we have API 5L X80, a steel widely used in the manufacture of pipelines for oil and natural gas transmission lines in Brazil. In this work, the effect of thermomechanical sequences on the mechanical properties of this steel was studied. For this, samples were cut and, with them, three thermomechanical routes were carried out (heating → lamination → cooling in water). After heating up to 950 ºC to austenitize the steel and remaining at this temperature for 15 minutes, the samples were laminated, achieving a reduction of thickness of 10%, 15% and 20%. Then, the samples were abruptly cooled in water at room temperature, thus carrying out the tempering treatment. After that, the specimens were manufactured to carry out tensile tests on the samples from the 3 thermomechanical routes and the material in the condition of “as received.” After processing the data, it was observed that, among the three routes, Route 1 was the one that presented the highest values of yield strength and resistance limit. Route 3, on the other hand, among the three routes performed, was the one that presented the highest specific deformation value. In general, the samples of all routes performed showed improvements in their mechanical properties when compared to the samples of the material as received. Thus, the thermomechanical sequences performed proved to be a good way to modify/improve the mechanical properties of API 5L X80 steel.