scholarly journals Comparative study of laser surface hardening of 50CrMo4 steel using continuous-wave laser and pulsed lasers with ms, ns, ps and fs pulse duration

2019 ◽  
Vol 366 ◽  
pp. 311-320 ◽  
Author(s):  
Niroj Maharjan ◽  
Wei Zhou ◽  
Yu Zhou ◽  
Yingchun Guan ◽  
Naien Wu
Keyword(s):  
Comparative Study ◽  
Pulse Duration ◽  
Surface Hardening ◽  
Continuous Wave ◽  
Laser Surface ◽  
Continuous Wave Laser ◽  
Pulsed Lasers ◽  
Laser Surface Hardening ◽  
Wave Laser

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 Continuous-wave laser generation at ~21 µm in Ho:KRE(WO_4)_2 (RE = Y, Gd, Lu) crystals: a comparative study

2011 ◽  
Vol 19 (25) ◽  
pp. 25279 ◽  
Author(s):  
Venkatesan Jambunathan ◽  
Xavier Mateos ◽  
Maria Cinta Pujol ◽  
Joan Josep Carvajal ◽  
Francesc Díaz ◽  
...  
Keyword(s):  
Comparative Study ◽  
Continuous Wave ◽  
Laser Generation ◽  
Continuous Wave Laser ◽  
Wave Laser

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.

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