Per: Ana Carolina Accioly Monteiro (Instituto Militar de Engenharia), Gabriel Ribeiro Barbosa (Instituto Militar de Engenharia), Wagner Antonio Loureiro Lima Krepke (Instituto Militar de Engenharia), Gabriel Onofre do Nascimento (Instituto militar de engenharia), Mônica Aline Magalhães Gurgel (Instituto militar de engenharia), Marcelo Henrique Prado da Silva (Instituto Militar de engenharia), Andersan dos Santos Paula (Instituto Militar de Engenharia)
Abstract:
In the present work, the instrumented ultramicrohardness test that explores certain mechanical properties was explored, to assess whether there are changes made due to the change in the microstructure of steel. The conditions analyzed were as a premium for Hot Rolling (HR) and Cold Rolling (BFH), as well as Intercritical Continuous Annealing (BFF) in the industrial production of “Dual Phase” (DP) or biphasic steel. Among these differences, the phases are one of the main changes in the microstructure, as in Hot and Cold Rolled conditions they have free ferrite and second phase (main constituents are divided into perlite, bainite and some tiny fraction of martensite-austenite constituent - MA), but differ of the free ferrite without deformation in the HR condition, whereas in the BFH condition, the ferrite, be it free ferrite, ferrite contained in the pearlite or ferrite contained in the bainite, is hardened. In the condition of Continuous Intercritical Annealing, it presents free ferrite (both with hard-grained and recrystallized grains in a larger fraction) and the second phase (main constituent MA), characterizing the microstructural aspect of a DP steel. Thus, because BFH has a very large concentration of hardened ferrite, it is to be expected that its hardness, mechanical strength and yield limit is greater than that of BFF and HRC. With the results of the instrumented ultramicrohardness tests, it can be seen that BFH had greater Vickers, DHV-1, DHV-2 and Hit hardness, confirming that it has greater hardness, mechanical resistance and yield limit. And yet, after analyzing the results obtained in each mechanical property, the identification module is shown to be the most sensitive, with the elastic ratio being the least affected among the three changes studied. Therefore, the tests proved that the ultramicrodurometer is a tool with the ability to present an acceptable prognosis to determine the mechanical properties for such steels.
