scholarly journals Hardening Efficiency and Microstructural Changes during Laser Surface Hardening of 50CrMo4 Steel

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2015
Author(s):  
Niroj Maharjan ◽  
Naien Wu ◽  
Wei Zhou
Keyword(s):  
Surface Hardening ◽  
Continuous Wave ◽  
Laser Energy ◽  
Laser System ◽  
Laser Surface ◽  
Energy Utilization ◽  
Continuous Wave Laser ◽  
Power Laser ◽  
Laser Surface Hardening ◽  
Hardened Surface

Laser surface hardening is an attractive heat treatment solution used to selectively enhance the surface properties of components by phase transformation. A quantitative parameter to measure the efficacy of hardening processes is still lacking, which hinders its application in industries. In this paper, we propose a simple approach to assess the effectiveness of the process by calculating its thermal efficiency. The proposed method was applied to calculate the hardening efficiency during different laser processing conditions. This study revealed that only a small portion of supplied laser energy (approximately 1–15%) is utilized for hardening. For the same laser system, the highest efficiency is achieved when surface melting is just avoided. A comparative study showed that pulsed lasers are more efficient in energy utilization for hardening than continuous wave laser. Similarly, the efficiency of a high-power laser is found to be higher than a low-power laser and an increase in beam absorption produces higher hardening efficiency. The analysis of the hardened surface revealed predominantly martensite. The hardness value gradually decreased along the depth, which is attributed to the decrease in percentage of martensite.

scholarly journals LASER SURFACE HARDENING OF AISI 1055 STEEL IN WATER SUBMERGED CONDITION

2019 ◽  
Vol 27 (01) ◽  
pp. 1950087
Author(s):  
NIROJ MAHARJAN ◽  
WEI ZHOU ◽  
YU ZHOU ◽  
NAIEN WU
Keyword(s):  
Surface Hardening ◽  
Water Movement ◽  
Laser Energy ◽  
Surface Hardness ◽  
Surface Oxidation ◽  
Water Layer ◽  
Laser Surface ◽  
Laser Hardening ◽  
Laser Surface Hardening ◽  
Conventional Laser

Underwater laser hardening might produce better surface mechanical properties than conventional laser hardening in air due to additional cooling effect by water. However, it has not been studied in detail. This study investigates the effect of water layer on laser surface hardening of AISI 1055 steel. It is found that laser surface hardening is feasible with water layer up to 3[Formula: see text]mm above the steel surface. A higher surface hardness is achieved during underwater processing. This is attributed to fast cooling by water which facilitates complete martensitic transformation. Nevertheless, the hardened area is smaller than that in conventional laser hardening in air due to attenuation of laser energy. Above 3[Formula: see text]mm, the laser beam is severely attenuated due to formation of vapor plume. Furthermore, it is found that surface oxidation cannot be prevented completely even during underwater treatment, and the water movement results in random distribution of metal slag on the surface.

Mathematical Modeling of Heat Transfer in Laser Surface Hardening of AISI 1050 Steel

2011 ◽  
Vol 312-315 ◽  
pp. 381-386
Author(s):  
R. Sh. Razavi ◽  
G.R. Gordani ◽  
S. Tabatabaee
Keyword(s):  
Mathematical Modeling ◽  
Heat Transfer ◽  
Surface Hardening ◽  
Laser Energy ◽  
Hardened Layer ◽  
Laser Surface ◽  
Material Surface ◽  
Laser Surface Hardening ◽  
Proposed Model ◽  
Good Agreement

Laser surface hardening is a method used for surface modification without affecting the bulk properties of materials. Due to rapid cooling and little thermal penetration in the surface layer, a homogenous structure and little distortion are usually obtained. When a high power laser irradiates a material surface, a part of the laser energy is absorbed and conducted into the interior of the material. If the absorbed energy is high enough, the material surface will melt and even vaporizes. Consequently the temperature of the process is of promote importance to incorporate an appropriate structural layer. In this regard, a study has been carried out to implement a mathematical modeling method to control the temperature gradient, which affects on the depth of the hardened layer. The model is based on solving the heat transfer equation and such a condition by assuming that the thermo-physical properties of the material are independent of the temperature. To evaluate the application of the proposed model, laser surface hardening was carried out to AISI 1050 steel, using a 1 kW CO2 laser. It was shown that the experimental results obtained are in good agreement with the proposed model.

Eutectoid temperature of carbon steel during laser surface hardening

1996 ◽  
Vol 11 (2) ◽  
pp. 458-468 ◽  
Author(s):  
Chin-Cheng Chen ◽  
Chun-Ju Tao ◽  
Lih-Tyan Shyu
Keyword(s):  
Carbon Steel ◽  
Physical Properties ◽  
Surface Hardening ◽  
Continuous Wave ◽  
Three Dimensional ◽  
Laser Surface ◽  
Eutectoid Temperature ◽  
Temperature Dependent ◽  
Melted Zone ◽  
Laser Surface Hardening

A new method was developed to determine the eutectoid temperature, Ac1, of carbon steel during laser surface hardening. In the method a three-dimensional heat flow model with temperature-dependent physical properties was set up and solved for the temperature distribution employing a finite element method (FEM). Workpieces were heat-treated to produce a melted and hardened zone by a single pass of a continuous-wave TEM00 CO2 laser beam. The depth profile of the melted zone was used as a calibrator to solve the uncertainty imposed by the unknown surface absorptivity. Obtained was an Ac1 of, on average, 770 °C, a superheat of 47 °C compared to the equilibrium Ac1 of 723 °C. Furthermore, the numerical model was also employed to predict the hardened depth, and the results show that, for a depth of more than 100 μm, the eutectoid temperature 770 °C leads to a depth about 10% smaller than that predicted at 723 °C. The use of the temperature-dependent physical properties is critical; an error up to 80% could result if constant physical properties are used.

scholarly journals Experimental investigation on a novel approach for laser surface hardening modelling

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
L. Orazi ◽  
A. Rota ◽  
B. Reggiani
Keyword(s):  
Surface Hardening ◽  
Carbon Diffusion ◽  
Industrial Applications ◽  
Laser Surface ◽  
Simplified Approach ◽  
Laser Surface Hardening ◽  
Novel Approach ◽  
Laser Treatments ◽  
High Flexibility ◽  
Short Time

AbstractLaser surface hardening is rapidly growing in industrial applications due to its high flexibility, accuracy, cleanness and energy efficiency. However, the experimental process optimization can be a tricky task due to the number of involved parameters, thus suggesting for alternative approaches such as reliable numerical simulations. Conventional laser hardening models compute the achieved hardness on the basis of microstructure predictions due to carbon diffusion during the process heat thermal cycle. Nevertheless, this approach is very time consuming and not allows to simulate real complex products during laser treatments. To overcome this limitation, a novel simplified approach for laser surface hardening modelling is presented and discussed. The basic assumption consists in neglecting the austenite homogenization due to the short time and the insufficient carbon diffusion during the heating phase of the process. In the present work, this assumption is experimentally verified through nano-hardness measurements on C45 carbon steel samples both laser and oven treated by means of atomic force microscopy (AFM) technique.

scholarly journals Laser surface hardening of SS316L

2021 ◽  
Vol 1070 (1) ◽  
pp. 012107
Author(s):  
Ganesh Dongre ◽  
Avadhoot Rajurkar ◽  
Ramesh Gondil ◽  
Nandan Jaju
Keyword(s):  
Surface Hardening ◽  
Laser Surface ◽  
Laser Surface Hardening

A 2-µm Continuous-Wave Laser System for Safe and High-Precision Dissection During NOTES Procedures

2010 ◽  
Vol 55 (9) ◽  
pp. 2463-2470 ◽  
Author(s):  
Xavier Dray ◽  
Gianfranco Donatelli ◽  
Devi Mukkai Krishnamurty ◽  
Elena Dubcenco ◽  
Ronald J. Wroblewski ◽  
...  
Keyword(s):  
High Precision ◽  
Continuous Wave ◽  
Laser System ◽  
Continuous Wave Laser ◽  
Wave Laser

Laser Surface Hardening of Gray Cast Iron Used for Piston Ring

2002 ◽  
Vol 11 (3) ◽  
pp. 294-300 ◽  
Author(s):  
Jong-Hyun Hwang ◽  
Yun-Sig Lee ◽  
Dae-Young Kim ◽  
Joong-Geun Youn
Keyword(s):  
Cast Iron ◽  
Surface Hardening ◽  
Piston Ring ◽  
Gray Cast Iron ◽  
Laser Surface ◽  
Gray Cast ◽  
Laser Surface Hardening

Water-Jet Assisted Laser Surface Hardening of Medium Carbon Steel Using Fiber Laser

2018 ◽  
Author(s):  
Sagar Sarkar ◽  
Ashish Kumar Nath
Keyword(s):  
Surface Hardening ◽  
High Hardness ◽  
Medium Carbon Steel ◽  
Water Jet ◽  
Laser Surface ◽  
Peak Hardness ◽  
Bottom Surface ◽  
Thin Sheets ◽  
Laser Surface Hardening ◽  
Conventional Laser

Laser surface hardening of most of the industrial components require depth of surface modification in the range of 100–150 micron. Conventional laser surface hardening uses laser as a heat source to modify a particular area of the surface without melting in an inert gas environment. However, the hardened profile in this case shows peak hardness value at a certain depth from the top surface. Also, hardening the top surface to get relatively much higher hardness near the top surface in case of thin sheets becomes difficult due to accumulation of heat below the surface of the specimen which in turn lowers the cooling rate. Hence, self-quenching becomes inadequate. In the present study, an in-house fabricated laser processing head with coaxial water nozzle has been used to flow a laminar water-jet during the laser surface hardening process to induce forced convection at the top surface. Thus, heat gets carried away by the water-jet from the top surface and by the water from the bottom surface as well. Results show that with judicious selection of process parameters, it is possible to get higher hardness (800 HV) to that of conventional laser surface hardening (500 HV) at the top surface using this process. Present process can be used for those cases where high hardness values are required near the top surface specially for thin sheets and thermally sensitive materials.

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