TITLE:
Study of Influence of the Peak Current Time in Microstructure of a Coating Hard Made by GTAW-P Process
AUTHORS:
Eduardo Ferracin Moreira, Paulo Cezar Moselli, João Roberto Sartori Moreno
KEYWORDS:
Hard Coating, FCAW-P, Dilution, Pulse Parameters
JOURNAL NAME:
Open Access Library Journal,
Vol.2 No.12,
December
30,
2015
ABSTRACT:
This paper presented analysis in
order to show the influence of welding pulse parameters on the microstructure
of the deposit, where a coating performed by GTAW-P process (Tungsten Arc
Welding with the Atmosphere Gas with deposition Powder). The coating was an
alloy of cobalt based on a substrate of a steel SAE 1020. The coating was
performed with pulsed current between 120 and 180 A, and the variations of
pulse parameters occurred between the time base and peak currents. Metallographic
analysis by electronic scanning microscopy (SEM), micro hardness testing and
determination of the dilution rate of the material were carried out. Thus, the
results demonstrated
that sample 3 showed
better results, such as the size of finer grains, medium high hardness about 65
HRC, 4.3% dilution rate and a lower heat transfer. Therefore, the spectrum
shown by scanning electron microscopy revealed the presence of hard carbides
(Co, Cr and W) in interdendritic region of the deposit, which explained the high levels of hardness.