Increasing Surface Hardness of S45C Steel by AIH-FPP/Gaseous Nitriding Treatment

Abstract

In this study, in order to increase surface hardness of S45C steel, hybrid surface modification treatment which is a combination of atmospheric controlled induction heating fine particle peening (AIH FPP) and gaseous nitriding, were developed. Surface microstructures of gaseous nitrided specimens pre treated with AIH FPP were characterized by a scanning electron microscope (SEM), an energy dispersive X ray spectrometer (EDX), X ray diffraction analysis (XRD) and X ray photoelectron spectroscopy (XPS). In the case of the AIH FPP treated specimens with a Cr transferred layer, the nitrided layer was not formed. This was because diffusion of nitrogen into the surface of the specimens was disturbed by chromium oxide in the transferred layer. On the other hand, the nitrided layer was formed at the surface of the specimen with Cr diffused layer induced by pre AIH FPP, and this nitrided layer showed higher hardness than that of the specimen without AIH FPP. However, the surface hardness decreased near the surface. In order to suppress decreasing of the surface hardness, the specimens with different Cr concentrations were prepared. It was clarified that the surface hardness was affected by Cr concentration in the Cr diffused layer; the lower the Cr concentration, the higher the surface hardness. It was assumed that the pore formation during nitriding process was inhibited by decreasing Cr concentration. These results suggest that surface hardness of S45C steel remarkably increases by hybrid surface treatments of AIH FPP and gaseous nitriding.

Evaluation of the Gas Nitriding of Fine Grained AISI 4135 Steel Treated with Fine Particle Peening and Its Effect on the Tribological Properties

“…1113) The authors have reported 11,12) that the local chromium concentration surrounding the porous region in the compound layer is high. Hosmani et al 13) reported that pores in the compound layer are formed due to recombination of nitrogen atoms to N 2 during the transformation of the ferrite matrix into iron nitrides surrounding CrN precipitates.…”

Effect of Cr Diffused Layer Formed by AIH-FPP Treatment on Adhesion of DLC Films to a Carbon Steel Substrate

“…It was previously reported that the thickness of the Cr diffused layer increases with the peening time and heating time during AIH-FPP treatment. 1,4,7,8) Therefore, we attempted to form thicker Cr diffused layers by doubling the peening time and heating time (peening time 60 s, heating time 120 s) during AIH-FPP treatment. Figure 8 shows the results of EDX analysis at the longitudinal section of the specimen subjected to AIH-FPP treatment under above conditions.…”

“…46) It was also reported that when nitriding is applied to steels with a Cr diffused layer, the nitrided layer formed had higher hardness. 7,8) The use of particles that are highly reactive with the substrate has recently been determined to form intermetallic compounds composed of the elements of the shot particles and substrate on the treated surface. 913) In this research, we attempted to use AIH-FPP treatment as a pretreatment for coating of a carbon-based hard thin film of diamond-like carbon (DLC).…”

Surface Modification of Carbon Steel by Atmospheric-Controlled IH-FPP Treatment Using Mixed Chromium and High-Speed Steel Particles

“…In addition, we conducted a study on the improvement effect and a series of experiments attempting to elucidate the mechanism underlining the effect of atmospheric-controlled induction heating and ne particle peening (AIH-FPP) [18][19][20][21][22][23][24][25] . For example, it was previously reported that by performing AIH-FPP on carbon steel using Cr particles, the components of the Cr particles were transferred onto the surface to be processed and diffused inside the substrate to form a Cr diffusion layer, whereby the corrosion resistance of the carbon steel was improved 22) .…”