WEAR OF LASER SURFACE HARDENED STEELS

4 Apr. 2013 Ing. Pavla Fišerová

RESULTS PUBLISHED IN THE PRESENTATION WERE OBTAINED IN THE SGS-2013-083 PROJECT

Laser Line (Pmax=4 kW), Kuka 16 HA [1]

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Overview

1) Laser surface hardening

2) Goal of the presentation

3) Overlap zone

4) Wear tests and materials

5) Pin-on-Disk test

6) Cyclic impact test

7) Conclusion

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Goal of the presentation

??? ???

Laser surface hardening [2]

Customers of MATEX PM would like to know whether the wear rate of laser-hardened steel is the same as or higher than that of induction-

hardened steel

Minimized distortion High quality of hardened layer High process speed Processing of complex shapes No surface cracks Environment-friendliness

Distinct transitional area Relatively low depth of hardened layer

LASER SURFACE HARDENING

- Different type and rate of wear - May lead to a high wear difference between overlap and laser track areas

Could we affect an overlap area?

Mould for automotive industry [3]

Cogwheel

gear pinion [4]

3) Sometimes we cannot control the overlap

2) In most cases, overlap is not used in functional areas

1) Overlap zones are not always necessary

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Overlap Zone

Why Study the Overlap Area?

Differences in wear rates !!!

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Specimen 2 hardening tracks

380 HV 10

653 HV 10

OVERLAP AREA

Fracture, C45 steel,magn. 10x

Fracture, C45 steel,

magn. 500x

C45 steel, magnification 50 x

C45 steel, magn. 500 x

Overlap zone

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Wear Tests

1) PIN-ON-DISK TEST

Aim of the test 1) Compare the wear behaviour of the laser track area and the overlap zone2) Compare the wear of laser-hardened

and induction-hardened materials

Test conditions

- wear profile was measured in Palacký university in Olomouc

Pin-on-Disk test [5]

Sample hardened by laser 6/13

- 42CrMo4 steel (ČSN 15 142)- Hardness after laser surface hardening: 55 HRC- Number of cycles: 100 000- PIN material: Al2O3

Pin-on-Disk Test Results

distance [µm]

1 2 3 4 5 6 7 8 9 10 110

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

32102 33540

4487950580 50939

56452

72308 74814

87254

we

ar

are

a [

µm

2]

Laser hardened - overlap zone

Laser hardened – laser track

Induction hardened

Track 1 (Ø 30 mm)Track 1 (Ø 30 mm) Track 2 (Ø 35 mm) Track 3 (Ø 40 mm)

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ONLY 3 %

Wear tests

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Aim of test

Test conditions

- Number of cycles = 100 000- F = 400 N

- Materials

Impact test

Hammer

2) CYCLIC IMPACT TEST

1) Compare the wear of laser-hardened surface and induction-hardened surface

- 1.2379 (ČSN 41 9573)1) soft-annealed2) quenched and tempered

- 1.6582 (ČSN 41 6343)1) quenched and tempered

- 6 impact craters were created in each specimen- Crater area was measured → An arithmetic characteristic of the wear area was obtained- 1.6582 and 1.2379 steels were used

Sample

Impact test results

0

20000

40000

60000

80000

100000

120000

140000

160000

Cra

ter

are

a [

µm

2]

1.2379 1.2379 QT 1.6582 QT

Laser hardened

Induction hardened

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Conclusion

- Average amounts of wear were evaluated for the overlap area and the laser track area- 42CrMo4 material

1) DIFFERENCES BETWEEN WEAR OF OVERLAP ZONE AND HARDENED AREA AFTER LASER SURFACE HARDENING (PIN-ON-DISK TEST)

Wear tests have not shown a large deviation in the amount of wear in the overlap area.

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1 2 3 4 5 6 7 8 90

10000

20000

30000

40000

50000

60000

70000

80000

3210233540

5058050939

7230874814

we

ar

are

a [

µm

2]

Track 1 (Ø 30 mm)

Track 1 (Ø 40 mm)

Track 1 (Ø 35 mm)

Laser hardened - hardened area

Laser hardened - overlapped zone

The biggest difference between amounts of wear in overlap and track zones was 3 % .

Conclusion

2) DIFFERENCES BETWEEN WEAR OF LASER SURFACE HARDENING (OVERLAP AND HARDENED AREA) AND INDUCTION HARDENING (PIN-ON-DISK TEST)

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1 2 30

5000100001500020000250003000035000400004500050000

32102 33540

44879

we

ar

are

a [

µm

2]

Track 1 (Ø 30 mm)

IND

UCT

ION

LASE

R O

VERL

AP Z

ON

E

LASE

R H

ARD

ENED

ZO

NE

Wear tests revealed that the wear rate is much higher in induction-hardened steel than in laser-hardened steel

Reduced component life

Need for more frequent replacement in service

Approx. 15% increase in costs

Conclusion

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0

50000

100000

150000

200000

110498

147598

Cra

ter

are

a[µ

m2

]

IND

UCT

ION

LASE

R

1.2379 QT

LASER

If you would like to have a lower wear...

3) DIFFERENCES BETWEEN WEAR OF LASER-HARDENED SURFACE (OVERLAP AND LASER TRACK AREAS) AND INDUCTION-HARDENED SURFACE (IMPACT TEST)

The cyclic impact test revealed considerably higher wear rates under dynamic loading in induction-hardened steel than in laser-hardened steel

THANK YOU FOR YOUR ATTENTION

[1] www.matexpm.com[2] www.sciencedirect.com[3] www.indiamart.com[4] www.mtjjg.com[5] www.laserarc.com

LITERATURE