Abstracts Book - IMRC 2018

• SD7-P044
MICROHARDNESS AND MICROSTRUCTURAL BEHAVIOR IN 35Cr-
45Ni CAST HEAT-RESISTING ALLOY AS A FUNCTION OF AGING
TIME
Sergio Haro 1 , Ireri Aydée Sustaita Torres 1 , Rosa Dolores Ortega Reyes 2 , Rafael Colás 2
1 Universidad Autónoma de Zacatecas, Unidad Académica de Ingeniería, Mexico. 2 Universidad
Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, Mexico.
Heat-resisting cast alloys are designed to sustain operation while being exposed
to temperatures greater than 1000°C. These alloys have widespread uses in the
Oil industries, for direct reduction of iron ore plants, chemical, and commercial
heat treating industries; in addition, due to their exceptional resistance, they can
be held into oxidizing, sulfidizing, or carburizing environments. The principal
attributes of these alloys are creep strength, corrosion resistance, excellent
carburization resistance, and ability to handle the cyclic conditions. The aim of
this study was to determine the effects of time of aging on microstructure and
microhardness of cast 35Cr-45Ni-0.5C heat-resistant alloy. The behavior of this
alloy during aging was examined by optical and microhardness test in samples
aged at 750°C for 0 h, 168 h, 336 h, 504 h, 672 h, 840 h, and 1008 h. The changes
of the aging times show the increase in microhardness in the aged samples as a
function of the time. The data indicate the evidence for the existence of two
plateaus, one at around 260 HV in the range of 0 - 336 h, and the second one at
around 290 HV, towards the longer aging periods. On the other hand, is possible
observed that the precipitation may have ended substantially after 672 hours at
750°C, that the explain the second plateaus. Another important result is that
even the shortest period of time analyzed 168 h is long enough to produce a
considerable amount of secondary precipitation, as confirmed by the increase
into around 50 HV of Vickers microhardness.
Keywords: Heat resisting alloys, Aging, Mechanical properties
Presenting authors email: haros907@hotmail.com