The effect of laser surface hardening on the surface hardness of mild steel

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.

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Experimental investigation on a novel approach for laser surface hardening modelling

International Journal of Mechanical and Materials Engineering ◽

10.1186/s40712-020-00124-0 ◽

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.

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Laser surface hardening of SS316L

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1070/1/012107 ◽

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

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Laser Surface Hardening of Gray Cast Iron Used for Piston Ring

CrossRef Listing of Deleted DOIs ◽

10.1361/105994902770344105 ◽

2002 ◽

Vol 11 (3) ◽

pp. 294-300 ◽

Cited By ~ 19

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

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

Volume 4: Processes ◽

10.1115/msec2018-6457 ◽

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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