Características mecânicas de vergalhões de aço auto-revenido

Abstract

The rebar steel is one of the most utilized and diffused materials in Brazilian civil construction, as it is in the whole world, but it´s necessary to know more details about the rebar behavior as a material and not only as a structural element. Each day civil engineering searches for new alternatives to maximize the use of materials, from new structural calculation tools, to new techniques in welding rebar steel. In that sense, this study shows the mechanic characteristics of the self-tempering rebar steel used in civil construction, analyzing in this case the 6.3 to 25.4mm bar diameter. The cooling process of the rebar, after lamination, know as self-tempering, produces a rebar steel with great mechanical characteristics, and low costs to the industry, but the beam turns to be constituted, in this process, by concentric layers with different mechanical proprieties. To study the influence of these layers in the rebar steel mechanical behavior, a microstructure characterization was made through analyses using optical and scanning electron microscopes, besides showing the profile of microhardness Vickers in every sample. From the results, we could see that only the 20 and 25.4mm bar had a thermal treatment by self-tempering of some relevance. It was chosen then, to peel the 20mm bar to obtain the tensile-deformation curves from the complete and peeled material, in order to observe its behavior within the extraction of the external layers, of superior hardness. The obtained results show that, with the extraction of the first layer and the reduction of the bar diameter from 20mm to 17mm, the tensile-deformation curves suffer a substancial decreasing, and from this point, the decreasing in the other reductions turns to be derisive.