EFFECT OF SALT BATH NITRIDING ON SURFACE ROUGHNESS BEHAVIOUR OF AISI 4140 STEEL
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Date
2017-01-23
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Publisher
Acta Metallurgica Slovaca
Abstract
In the present research, AISI 4140 steel was nitrided in salt bath to study and analyze the behaviour
of the surface roughness. The structural surface characterization behaviour of the nitrided steel
was compared to the behaviour of the same steel which was untreated. The nitriding process was
implemented in the salt bath component at ten different times (from 1 h to 10 h) when the
temperature was constant at (580ºC). The influence of nitriding treatment on structural properties
of the material was studied by scanning electron microscopy (SEM), microhardness tester and
surface profilometer. It was found that salt bath nitriding was effective in improving the surface
properties behaviour of this steel. Experimental results showed that the nitrides ε-Fe2-3(N,C) and
γ’-Fe4(N,C) present in the compound layer increase the microhardness (406–502 HV0.3), the
initial surface roughness values of nitrided samples were higher than those of unnitrided
specimens, it also observed that the increasing the nitriding time increases the surface roughness
parameters (Ra, Rq and Rz).
Description
In the present research, AISI 4140 steel was nitrided in salt bath to study and analyze the behaviour
of the surface roughness. The structural surface characterization behaviour of the nitrided steel
was compared to the behaviour of the same steel which was untreated. The nitriding process was
implemented in the salt bath component at ten different times (from 1 h to 10 h) when the
temperature was constant at (580ºC). The influence of nitriding treatment on structural properties
of the material was studied by scanning electron microscopy (SEM), microhardness tester and
surface profilometer. It was found that salt bath nitriding was effective in improving the surface
properties behaviour of this steel. Experimental results showed that the nitrides ε-Fe2-3(N,C) and
γ’-Fe4(N,C) present in the compound layer increase the microhardness (406–502 HV0.3), the
initial surface roughness values of nitrided samples were higher than those of unnitrided
specimens, it also observed that the increasing the nitriding time increases the surface roughness
parameters (Ra, Rq and Rz).