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

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1487
Author(s):  
Won-Sang Shin ◽  
Hyun Jong Yoo ◽  
Jeoung Han Kim ◽  
Jiyeon Choi ◽  
Eun-Joon Chun ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Base Metal ◽  
Surface Hardening ◽  
Surface Hardness ◽  
Laser Heat Treatment ◽  
Laser Nitriding ◽  
Laser Heat ◽  
Heat Treated ◽  
Pin On Disk

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.

scholarly journals Correlation between Microstructure and Tribological Properties of Laser Surface Heat-Treated Stellite Coatings

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 433
Author(s):  
Chang-Kyoo Park ◽  
Jung-Hoon Lee ◽  
Nam-Hyun Kang ◽  
Eun-Joon Chun
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Tribological Properties ◽  
Superior Performance ◽  
Laser Heat Treatment ◽  
Continuous Casting Mold ◽  
Heat Treated Sample ◽  
Laser Heat ◽  
Heat Treated ◽  
Sprayed Coating

To manufacture superior-performance continuous casting mold components, high-velocity oxygen fuel spraying of a Stellite-1 coating was followed by its laser heat treatment at 1373–1473 K using a diode laser. The effects of the laser irradiation conditions on the macro- and microstructural variations along with the hardness and wear resistance within the Stellite-1 coating were evaluated. After the heat treatment, micro-voids within the sprayed coating decreased in number slightly with an increase in the heat treatment temperature. The hardness of the sprayed Stellite-1 coating increased from that of the as-sprayed coating (680 HV) after the laser heat treatment, with a hardness of 860 HV obtained at 1473 K. The cause of the increase in hardness could be the formation of nano-sized W- and Cr-based carbides such as WC, M7C3, and M23C6, as suggested by transmission electron microscopy analysis. The tribological properties of as-sprayed and laser heat-treated samples were investigated by a pin-on-disk tribometer. The laser heat treatment of Stellite-1 coating enhanced wear resistance. This resulted in a lower coefficient of friction and wear rate for the laser heat-treated sample than those for the as-sprayed sample.

Formability of Ultrafine-Grained AA6016 Sheets Processed by Accumulative Roll Bonding

2012 ◽  
Vol 504-506 ◽  
pp. 575-580 ◽  
Author(s):  
Tina Hausöl ◽  
Christian W. Schmidt ◽  
Verena Maier ◽  
Wolfgang Böhm ◽  
Hung Nguyen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Laser Heat Treatment ◽  
Bending Tests ◽  
Roll Bonding ◽  
Laser Heat ◽  
Heat Treated ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure ◽  
Bending Behaviour

Aluminium alloy AA6016 was accumulative roll bonded up to eight cycles in order to produce an ultrafine-grained microstructure. The formability of these sheets was investigated by means of bending tests. Furthermore the influence of a local laser heat treatment at the bending edge is observed. The strength of the UFG samples is increased by a factor of around two compared to the conventionally grained T4 condition which also results in up to 50 % higher punch forces needed for bending of ARB processed samples. An anisotropic bending behaviour is observed. By applying a tailored laser heat treatment along the bending edge prior to the bending tests a local recrystallization and recovery at the deformation zone of the samples is achieved. Thus, ductility is increased locally whereby bending to an angle of 80° is possible with lower forming forces compared to the non-heat treated specimens. The results are compared to previous studies on mechanical properties and formability investigations of ARB processed AA6016.

scholarly journals Nanostructuring Behavior of NiCrBSi and CoCrWC Thermal Spray Coatings Formed by Temperature-Controlled Laser Heat Treatment

2020 ◽  
Vol 58 (4) ◽  
pp. 247-256 ◽  
Author(s):  
Eun-Joon Chun
Keyword(s):  
Heat Treatment ◽  
Thermal Spray ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Laser Heat Treatment ◽  
Real Time Control ◽  
Continuous Casting Mold ◽  
Time Control ◽  
Laser Heat ◽  
Heat Treated

.For surface hardening of a continuous casting mold component, a thermal spray coating of NiCrBSi (Metco-16C) and CoCrWC (Stellite-1) was performed followed by laser heat treatment of the coatings. To support selective modification of the thermal spray coating, a metallurgically determined surface temperature was maintained during the laser heat treatment, by real-time control of the laser power. In other words, nonhomogeneities in the macrosegregation of certain alloying elements, and voids in the as-sprayed state, could be improved. The main microstructural features of the Metco-16C coating laser-heat-treated at 1423 K were nanosized (100–150 nm) Cr5B3, M7C3, and M23C6 precipitates with a lamellar structure of Ni (FCC) and Ni3Si as the matrix phase. Those of the laser heat-treated Stellite- 1 coating at 1473 K were fine (30–250 nm) precipitates of WC, M7C3, and M23C6 based on a Co (FCC) matrix. The results show that laser heat treatment at 1423 K increased the hardness of the Mecto-16C coating to 1115 HV from the as-sprayed state (754 HV), while treatment at 1473 K increased the hardness of the Stellite-1 coating from 680 HV to 860 HV.

Improving the Properties of Magnetic Bearing Shaft Material by HVOF Coating of WC-Metal Powder and Laser Heat Treatment

2012 ◽  
Vol 560-561 ◽  
pp. 1052-1058 ◽  
Author(s):  
T.Y. Cho ◽  
Y.K. Joo ◽  
J. H. Yoon ◽  
H. G. Chun ◽  
S.H. Zhang
Keyword(s):  
Heat Treatment ◽  
Metal Powder ◽  
Laser Heating ◽  
Surface Hardness ◽  
Magnetic Bearing ◽  
Free Carbon ◽  
Laser Heat Treatment ◽  
Friction Coefficients ◽  
Hvof Coating ◽  
Laser Heat

Abstract. Micron-sized WC-metal (WC-0.6%C-21%Cr-6%Ni) powder was coated onto the substrate of magnetic bearing shaft material Inconel718 (substrate or In718) using JK3500 HVOF thermal sprayer for the improvement of the surface properties of the substrate. The optimal coating process for the highest surface hardness was obtained using the Taguchi experimental program. The coating was laser heat-treated (LH) by CO2(g) laser for further improvement of the properties. During the thermal spraying, a small portion of metal carbides of powder decomposed to W2C, metals and free carbon. The free carbon reacted with excessively sprayed oxygen, and formed carbon oxide gases, forming porous coating. By laser-heating, porosity decreased and the porous strips at the interface of coating and substrate (coat/sub) compacted. At the interface, the precipitated graphite concentration decreased and the metal elements diffused from both the coating and substrate increased, enhancing the functions as buffer zone and increasing adhesion of coating. The surface hardness of substrate increased by coating and further increased by laser-heating from 410±30 Hv to 983±101 Hv and 1425±94 Hv respectively. Porosity of coating decreased by laser-heating from 2.6±0.4% to 0.35±0.06%, and coating thickness shrank from 280㎛ to 200㎛. Friction coefficients of substrate decreased from 0.52±0.02 to 0.36±0.04 by coating, because the free carbon formed by decomposition of WC to W2C functioned as a solid lubricant. By increasing sliding surface temperature from 25°C to 450°C, the friction coefficients of substrate and coating were decreased from 0.52±0.02 to 0.31±0.02 and from 0.36±0.04 to 0.23±0.04 respectively, because of easy formation of free carbon and metal oxides which functioned as solid lubricants. Wear depth of surface was decreased by coating and by LH coating from 55µm to 32 µm and to 12 µm respectively. HVOF coating of WC-metal powder on In718 surface and laser heat-treatment of the coating are highly recommended for the improvement of the properties of magnetic bearing shaft.

scholarly journals Improvement of Surface Properties of Inconel718 by HVOF Coating with WC-Metal Powder and by Laser Heat Treatment of the Coating

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Hui Gon Chun ◽  
Tong Yul Cho ◽  
Jae Hong Yoon ◽  
Gun Hwan Lee
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Metal Powder ◽  
Surface Properties ◽  
Porous Coating ◽  
Wear Depth ◽  
Laser Heat Treatment ◽  
Hvof Coating ◽  
Laser Heat

High-velocity oxygen-fuel (HVOF) thermal spray coating with WC-metal powder was carried out by using optimal coating process on an Inconel718 surface for improvement of the surface properties, friction, wear, and corrosion resistance. Binder metals such as Cr and Ni were completely melted and WC was decomposed partially to W2C and graphite during the high temperature (up to 3500°C) thermal spraying. The melted metals were bonded with WC and other carbides and were formed as WC-metal coating. The graphite and excessively sprayed oxygen formed carbon oxide gases, and these gases formed porous coating by evolution of the gases. The surface properties were improved by HVOF coating and were improved further by CO2laser heat treatment (LH). Wear resistance of In718 surface was improved by coating and LH at 25°C and an elevated temperature of 450°C, resulting in reduction of wear trace traces, and was further improved by LH of the coating in reducing wear depth. Corrosion resistance due to coating in sea water was improved by LH. HVOF coating of WC-metal powder on a metal surface and a LH of the coating were highly recommended for the improvement of In718 surface properties, the friction behavior, and wear resistance.

Control Quality on Process of Laser Heat Treatment

2018 ◽  
Vol 941 ◽  
pp. 1860-1866
Author(s):  
Maria Angeles Montealegre ◽  
Beñat Arejita ◽  
Piera Alvarez ◽  
Carlos Laorden ◽  
Javier Diaz-Rozo
Keyword(s):  
Heat Treatment ◽  
Cross Sections ◽  
Surface Hardening ◽  
New Technology ◽  
Laser Hardening ◽  
Laser Heat Treatment ◽  
Hardening Process ◽  
Laser Heat ◽  
Sharp Edges ◽  
Hardness Values

Laser surface hardening, is a process in which a shaped laser beam is scanned across the surface to produce a hard and wear-resistant surface on components. Compared with the conventional surface hardening process, the laser heat treatment offers a number of attractive characteristics such as minimal part distortion, self-quenching and the need for less finishing work. The challenge of laser hardening is the uneven surfaces found in molds such as those with sharp edges or holes. In these cases, due to the differences in the surrounding volume of the material, overheating problems often appear leading to unacceptable treatment results. The purpose of this paper is to present the new technology, “raio” developed by Talens System for laser hardening process. This technology is able to adapt to geometrical singularities of the components to be treated, ensuring the dimensions of the hardened area and hardness values are compliant with the requirements. The main features of the technology for laser hardening are validated on a set of samples of 1.2738 steel with representative discontinuities of molds. Mechanical and microstructural characterizations of the hardened cross sections confirm the advantages of the raio technology in regard to the quality compliance of the laser hardening process. Furthermore, raio offers the same advantages for other laser processes, like softening of critical area or laser cladding for repairing of damaged components.

scholarly journals Effect of laser heat treatment on structure and wear resistance of cobalt stellite

2019 ◽  
Vol 1396 ◽  
pp. 012016
Author(s):  
E L Furman ◽  
E A Usoltsev ◽  
I S Bakhteev ◽  
I E Furman ◽  
A V Shak
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Laser Heat Treatment ◽  
Laser Heat
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