University of MiskolcUniversity of Miskolc

Department of Mechanical EngineeringDepartment of Mechanical Engineering

Modelling of Laser Surface Treatment

Tutor: Dr. Mária Kocsis Báan

Consultant: Mr. Reza Roshan

By: Mohamad HoneinehMohamad Honeineh

M.Sc. ThesisM.Sc. Thesis

Experimental MethodologyExperimental Methodology

Steel grades C45, C60, S100 (Hungarian standard)

Workpice dimensions 6056 10 (mm)

Laser beam diametere 10 (mm) 9 combinations of technological

paramerter:• Laser power 1,2,3 (kW )• Sacnning rates 300,500,700

(mm/min) Surface coated by graphite

Preparation StagesPreparation Stages

Sectioning was accomplished by water jet cutting machine

Grinding Rough and Fine Polishing The sectioned specimens were

etched in Nital macro- & microphotos were

placed in synchronization with the HV microhardness results

Laser Treated C45 Steel

1 mm 1 mm 1 mm

0

200

400

600

800

-6.4 -4.8 -3.2 -1.6 0 1.6 3.2 4.8 6.4

Width(mm)

Har

dnes

s(H

V)

300 mm/min

0

200

400

600

800

-6.4 -4.8 -3.2 -1.6 0 1.6 3.2 4.8 6.4

Width(mm)

Har

dnes

s(H

V)

500 mm/min

0

200

400

600

800

-6.4 -4.8 -3.2 -1.6 0 1.6 3.2 4.8 6.4

Widht(mm)

Har

dnes

s(H

V)

700 mm/min

P = 2 kW, v = 300 mm/min P = 2 kW, v = 500 mm/min P = 2 kW, v = 700 mm/min

Experimental ResultsExperimental Results

No significant changes were observed for 1 kW laser power

For 2 and 3 kW laser power, the phase transformation depth decreased when the scanning speed was the fastest

Slow scanning speeds caused wider and deeper hardened tracks

For high laser power with fast scanning rates high hardness was achieved

Homogeneous austenite was obtained at slow scanning rate

Three Dimensional ModellingThree Dimensional Modelling

The same geometry was built using SYSWELD SOFTWARE as that in the original experiments

A Conical heat source was implemented into the SYSWELD by using simplified FORTRAN programming

Due to the symmetry of the workpiece, the fine mesh created resembled only half the workpiece

3kW Laser Power3kW Laser Power

v=300 mm/min

v=700 mm/min

v=500 mm/min

Time-Temperature CurvesTime-Temperature Curves

Ac 3

0 1 2 3 4 5 6 7 8

2000

1800

1600

1400

1200

1000

800

600

400

200

0

Ac 3

A 3

time,s

Temp.(°C)node 5413node 5414node 5415node 5416node 5417node 541818 mm

Conical and Gaussian ModelConical and Gaussian Model

x

z

y

re

ri

q max

v=500 mm/min v=500 mm/min

Conical and Gaussian ModelConical and Gaussian Model

1 800

1600

1400

1200

1000

800

600

400

200

0

0 0.5 1 1.5 2 2.5 3 3.5

time, s

Temp. (°C)Time-temp. Cycles for C60 steel, at 2 kW and scanning speed 500 mm/min for: Conical heat source model

Gaussian heat source model

Simulation ResultsSimulation Results

Higher was the laser power, higher the temperature Spot size was greatly influenced by the laser power and

scanning rate Time-Temperature Curves indicate that very fast cooling

occurs Bigger thermal conductivity factor, lower was the

Temperature Gaussian model obtained steeper and sharper cycles than

that of a conical model Changing the absorptivity factor by 0.1 step increment

results in 200-300°C difference in maximum temperature