LOHOCA, J.; http://lattes.cnpq.br/1633135476596500; LOHOCA, João.
Résumé:
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.
