AISI 1005 Steel Plasma Treated by Different Thermochemical Surface Treatments

Abstract

To modify the surface structure of AISI 1005 steel and its properties without any dimensional loss, different plasma surface treatments were performed at low temperatures (500 °C) in this study. The samples were subjected to single plasma treatments including: nitriding (N5% and N3%), carburizing (CE) and ferritic nitrocarburizing (NC) and to duplex treatments of nitriding followed by carburizing (N5%+CE and N3%+CE) and ferritic nitrocarburizing followed by carburizing (NC+CE). The gas mixture used for these treatments was varied as follows: nitriding (5%N 2 +95%H 2 and 3%N 2 +97%H 2 ), carburizing (5%CH 4 +95%H 2 ) and ferritic nitrocarburizing (5%N 2 +1.5%CH 4 +93.5%H 2 ). A microstructural characterization of the samples was carried out using optical and scanning electron microscopy in addition to XRD analysis. Microhardness testing was also performed. The XRD analysis showed a stabilization of the outermost cementite layer for all of the carburizing treatments. The results show that a greater hardness increase was achieved for the nitriding treatment as well as a more regular compound layer. However, a greater depth of hardening was obtained in samples with NC+CE and N5%+CE, which extended to the hardened depth to 800 μm.

Study of the Thermochemical Surface Treatment Effect on the Phase Precipitation and Degradation Behaviour of DSS and SDSS

“…In addition, as mentioned before, no pitting potential is reached. Regarding the plasma carburizing at lower temperatures, carbon presents lower diffusivity, and consequently, low solubility in the ferrite phase (0.0025%) [48]. Therefore, the adsorbed carbon atoms on the surface do not have enough mobility to diffuse into the substrate, a saturation of the carbon Usually carbides and nitrides are responsible for the decrease in corrosion resistance in such processes at low temperatures [13,25,41].…”

“…Regarding the plasma carburizing at lower temperatures, carbon presents lower diffusivity, and consequently, low solubility in the ferrite phase (0.0025%) [48]. Therefore, the adsorbed carbon atoms on the surface do not have enough mobility to diffuse into the substrate, a saturation of the carbon on the surface is then caused and cementite is precipitated after fast cooling.…”