Microstructural Characterization of Surface Softening Behavior for Cu-Bearing Martensitic Steels after Laser Surface Heat Treatment

Chun, Eun−Joon; Sim, Ahjin; Kim, Min‐Su; Kang, Nam Jun

doi:10.3390/met8060470

Cited by 14 publications

(7 citation statements)

References 34 publications

(36 reference statements)

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“…A magnified SEM image (Figure 3b) was obtained and is shown in the red box in Figure 3a. A few nanometer-size particles were observed, and these are known as Cu particles [3,29,30]. Figure 4 shows the XRD profiles of the BM, LH P21, and LN P21.…”

Section: Resultsmentioning

confidence: 99%

“…Appropriate surface treatments can prevent damages to the mold, resulting in an extended mold lifespan. Several studies have investigated the application of surface treatments to mold steels and tool steels in the form of surface heat-treatment [2][3][4][5], nitriding [3,[6][7][8], surface coating and alloying [9][10][11][12], and peening [5,13,14]. Lee et al [2] investigated the laser melting-induced microstructural evolution and surface hardening of SM45C mold steel.…”

Section: Introductionmentioning

confidence: 99%

“…However, only a few studies have reported the influence of surface treatments on the microstructure, mechanical properties, and functional properties of AISI P21 mold steel. Our previous studies [3,7] investigated the influence of laser heat-treatment and laser nitriding on the microstructure and microhardness of P21 steel. These studies revealed that the laser heat-treatment did not induce surface hardening, and the laser nitriding parameters affected the microhardness and nitriding thickness.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Laser Heat-Treatment and Laser Nitriding on the Microstructural Evolutions and Wear Behaviors of AISI P21 Mold Steel

Shin

Yoo

Kim

et al. 2020

Metals

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Laser heat-treatment and laser nitriding were conducted on an AISI P21 mold steel using a high-power diode laser with laser energy densities of 90 and 1125 J/mm2, respectively. No change in surface hardness was observed after laser heat-treatment. In contrast, a relatively larger surface hardness was measured after laser nitriding (i.e., 536 HV) compared with that of the base metal (i.e., 409 HV). The TEM and electron energy loss spectroscopy (EELS) analyses revealed that laser nitriding induced to develop AlN precipitates up to a depth of 15 μm from the surface, resulting in surface hardening. The laser-nitrided P21 exhibited a superior wear resistance compared with that of the base metal and laser heat-treated P21 in the pin-on-disk tribotests. After 100 m of a sliding distance of the pin-on-disk test, the total wear loss of the base metal was measured to be 0.74 mm3, and it decreased to 0.60 mm3 for the laser-nitrided P21. The base metal and laser heat-treated P21 showed similar wear behaviors. The larger wear resistance of the laser-nitrided P21 was attributed to the AlN precipitate-induced surface hardening.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Laser Heat-Treatment and Laser Nitriding on the Microstructural Evolutions and Wear Behaviors of AISI P21 Mold Steel

Shin

Yoo

Kim

et al. 2020

Metals

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“…For instance, to improve the surface wear resistance, Houdková et al attempted the laser-based surface remelting of a thermal-sprayed Co-based alloy [9]. Furthermore, Santhanakrishnan et al, Chun et al and Shariff et al reported on the surface hardening that could be attained by applying laser-based surface heat treatment to tool and plastic molds, as well as railroad steels, respectively [10][11][12]. Hongchao et al also found that laser shock peening enhances the surface hardening behavior and fatigue resistance of titanium (Ti) alloys [13].…”

Section: Introductionmentioning

confidence: 99%

Influence of Laser-Assisted Fusing on Microstructural Evolution and Tribological Properties of NiWCrSiB Coating

Park

Chun

2020

Metals

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The present study examines the applicability of a diode laser-assisted fusing treatment and a temperature-control system to the NiWCrSiB thermal spray coating to develop the enhanced wear resistance of continuous-casting molds. As a result of the use of the lasers, the variations in the microstructure and the hardening behavior during the fusing treatment could be controlled. Fine secondary phases (approximately 0.05–10 μm in size) homogeneously present in the coating after the laser-assisted fusing were observed to be Cr-, Mo- and W-based carbides and borides. Transmission electron microscope analysis was used to characterize these fine secondary phases as M7C3 and M23C6 carbides and M5B3 boride. Because of these fine secondary phases, the hardness increased from 730 (as-sprayed status) to 1230 HV (after fusing at a temperature of 1473 K). Finally, given the formation of fine secondary phases and the occurrence of surface hardening, the laser-assisted fusing treatment was deemed to enhance the tribological performance of the thermal-sprayed coating, in that it exhibited a lower coefficient of friction and lower wear rate than the as-sprayed coating.

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“…The researcher indicated an improvement in the surface mechanical properties such as the micro-hardness and the wear resistance. The laser polishing of different metals has been investigated by several researchers in order to produce a better understanding of the effect of the input processing parameters and to relate them to the modified surface characteristics [34,35]. In order to fill the gap of information available for 316L stainless steel, this paper presents a study of the effect of laser polishing parameters of 316L stainless steel alloy on the resulting surface properties.…”

Section: Introductionmentioning

confidence: 99%

Laser Polishing of Additive Manufactured 316L Stainless Steel Synthesized by Selective Laser Melting

et al. 2019

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One of the established limitations of metal additive manufacturing (AM) methods, such as selective laser melting (SLM), is the resulting rough surface finish. Laser polishing is one method that can be used to achieve an improved surface finish on AM printed parts. This study is focused on the laser surface polishing of AM parts using CO2 laser beam irradiation. Despite the fact that several researchers have investigated the traditional abrasive polishing method, there is still a lack of information reporting on the laser surface polishing of metal parts. In this study, AM 316L stainless steel cylindrical samples were polished using CO2 laser beam irradiation in continuous wave (CW) working mode. Two design of experiment models were developed for the optimization of the input processing parameters by statistical analysis of their effect on the resulting roughness. The processing parameters investigated were the laser beam power, the rotational speed of the sample, the number of laser scan passes, the laser beam focal position, and the percentage overlap of the laser tracks between consecutive passes. The characterization of the measured roughness and the modified layer microstructure was carried out using 3D optical and scanning electron microscopy (SEM). A maximum reduction of the roughness from 10.4 to 2.7 µm was achieved and no significant change in the microstructure phase type and micro-hardness was observed.

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Microstructural Characterization of Surface Softening Behavior for Cu-Bearing Martensitic Steels after Laser Surface Heat Treatment

Cited by 14 publications

References 34 publications

Effect of Laser Heat-Treatment and Laser Nitriding on the Microstructural Evolutions and Wear Behaviors of AISI P21 Mold Steel

Effect of Laser Heat-Treatment and Laser Nitriding on the Microstructural Evolutions and Wear Behaviors of AISI P21 Mold Steel

Influence of Laser-Assisted Fusing on Microstructural Evolution and Tribological Properties of NiWCrSiB Coating

Laser Polishing of Additive Manufactured 316L Stainless Steel Synthesized by Selective Laser Melting

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