Estudo da viabilidade de endurecimento de aços utilizando uma tocha de plasma como fonte energética.

Abstract

The present work presents fundamentally the study of the possibility and viability of superficial hardening of steels using as energy source a torch of pressed plasma. The work for now developed if it divides in two stages: i) Rising of the thermal profiles of heating and cooling traced starting from the data of time and temperature, aiming at quantize the heating rate and cooling, as well as the temperature in that the samples were submitted, ii) qualitative Analysis of the effects of the action of a plasma torch on the microstructures of the steels SAE 420 and SAE 4340. In the first stage it was verified that there are modifications of the thermal gradient for a same energy of the torch when this linked time is varied. The maximum temperatures increased with the factor energy, as well as the cooling rates. In the second stage it was consisted that after the heating and subsequent cooling the tests of hardness indicated significant increase in the superficial hardness. The work condition that originated more significant hardness than it was (1=18 A; Ib=2 A; f=10 kHz and times that varied from 5 to 25 seconds). The plasma equipment used in our laboratory (LabPlasma - Laboratory of Processing of Materials for Plasma/UFRN) it possesses a tension source pulsed with great versatility, through electronic/digital controls, we can control several parameters of the plasma: current, frequency, tied up time (ton), turned off time (t0ff), among others.