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Ing. Pavla Klufová1

Doc. Dr. Ing. Antonín Kříž1

doc. Ing. Stanislav Němeček, Ph.D., IWE2

Ing. Jiří Hájek, Ph.D.1

1Department of Material Engineering and

Engineering Metallurgy, ZČU Plzeň, Univerzitní

22, 306 14 Plzeň, Czech Republic

e-mail: klukova@kmm.zcu.cz 2MATEX PM, s.r.o., Morseova 5, 301 00 Plzeň

Abstract Technology of HPDD laser surface

hardening using high intensity of light radiation,

which leads to short time rapid warming up the

surface of material and rapid cooling due to thermal

conductivity. Basic contribution of this technology

is quick process of the treating without liquid

cooler. This type of treatment needs no machining

after laser surface hardening (shape changes are not

bigger than 20 µm on 2 mm thick hardened

surface), only for special needs is used grinding.

Other contribution of laser hardening is favorable

course residual strains, which are in this case the

greatest at surface in contrary of classic hardening.

It is because of cooling, which is caused by material

conductivity and goes into the material. These

favorable influences come to light during contact

wear and resulting degradation of surface. This

behavior study is subject of this article which is

aimed to wear analysis of the laser surface hardened

materials 1.2311 and 1.2379. The wear was

initiated by the „PIN-on-DISK“ testing. One of the

goals was to find out influence oxide layer (created

by hardening process) on wear resistance of

hardened surface, in compare with wear resistance

of hardened surface without oxide layer (removed

by the grinding). This experiment also deals with

compare of surface wear resistance in the

overlapping area, between hardened trails.

Key words: Laser surface hardening; wear ISSN

1335-08

1. INTRODUCTION

For this experiment were chosen 1.2311 and

1.2379 steels. Their chemistry is noted in Table 1.

Steels 1.2311 and 1.2379 were chosen,

because they were used in similar experiments in

past. This experiments was published at the

conferences Using laser beams in industry (Pilsen

2011) and Metal 2011 (Brno). Both types of steels

are appropriate for surface hardening due to

chemistry. Usually are used for die blocks in drop

hammers and forging pressers (1.2311) and for

injection pressers for plastics (1.2379).

Experimental part of this article was divided to two

parts. First was about the surface wear analysis

„PIN-on-DISK“ on specimens with oxide layers.

Tab.1. Chemistry of 1.2311 and 1.2379 steels

Volume (wt.%)

Element Steel 1.2311 Steel 1.2311

C 0,35 - 0,45 1,40 - 1,65

Mn 1,20 - 1,80 0,20 - 0,45

Si 0,50 - 0,90 0,20 - 0,45

P max. 0,030 max. 0,030

S max. 0,030 max. 0,035

Cr 1,70 - 2,20 11,00 - 12,50

Mo 0,20 - 0,40 0,60 - 0,95

V 0 0,80 - 1,20

The second part deals with same analysis

but, specimens was without oxide layer (removed

by the grinding). Tribological trails on specimens

was created by the „PIN” from the WC, and

conditions: F=10 N, v=154 turns/min, n=30000

cycles, without airflow or lubricants. Also was

recognized differences between surface wear

resistance in the overlapping area.(Fig. 1 – area A,

C) and area in center hardened trail (Fig. 1 – area B,

D).

Fig. 1 Placing of tribological trail on specimen

On degradation of specimens has influence

many factors. If pass away environment, the wear

process depends on hardness, roughness, structure

(chemistry, technology of treatment, orientation,

etc.) and residual strains. For process laser

hardened material is typical creation re-hardened

area in place overlapped area. Every technology for

WEAR BEHAVIOR OF LASER HARDENING TOOL STEEL 1.2311 AND 1.3279

mailto:klukova@kmm.zcu.cz

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surface hardening has the re-hardened area, but in

laser hardening occupies larger area. On the Fig. 2

is overlap between two hardened trails on 1.2311

steel. Fig. 3 and 4 shows details on surface in center

of hardened trail and in overlap area.

Fig. 2 Overlap trails, steel 1.2311, etched by Nital

3%, magnification 2,5x

Fig. 3 Structure of steel 1.2311 in center hardened

trail, etched by Nital 3%, magnification 50x

Fig. 4 Overlap trails, steel 1.2311, etched by Nital

3%, magnification 50x

On Fig. 3 and 4 are shown differences in structure

and in hardness. That is possible to expect

differences in wear in this areas. In further text are

mentioned results of analysis.

2.WEAR ON LASER HARDENED SURFACES

WITH OXID

Fig. 5 Overlap area - tribilogical trail, steel 1.2311,

magnification 5x

Fig. 6 Hardened area - tribilogical trail, steel

1.2311, magnification 5x

Fig. 7 Overlap area - tribilogical trail, steel 1.2311,

magnification 150x

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Fig. 8 Hardened area - tribilogical trail, steel

1.2311, magnification 150x

Fig. 9 Overlap area - tribilogical trail, steel 1.2311,

magnification 150x

On Fig. 5 and 6 is shown overlap area and

hardened area in tribilogical trail, steel 1.2311. The

trail has almost same width in every place (variance

to the 10%). Mostly on overlap places was 8 µm

thick oxide layer peel of from surface. In overlap

area and hardened area were found surfaces oxides

from previous heat treatment. Fig. 9 shown minimal

wear because of oxide layer hold still.

Fig. 10 Overlap area - tribilogical trail, steel steel

1.2379, magnification 5x

Fig. 11 Hardened area - tribilogical trail, steel steel

1.2379, magnification 5x

Fig. 12 Overlap area - tribilogical trail, steel 1.2379,

magnification 150x

Fig. 13 Hardened area - tribilogical trail, steel steel

1.2379, magnification 150x

Fig. 14 Overlap area - tribilogical trail, steel 1.2379,

magnification 150x

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The wear was bigger on steel 1.2379 in

compare with steel 1.2311. Greater degrease of

volume was caused by the carbide structure in steel

and their orientation. Overlap and hardened area

was wearied in same intensity in tribilogical trail.

Oxide layer was peel of from surface equally. Is

possible to conclude, that the overlap areas has no

influence on surface wear on surface hardened steel

1.2379.

3. WEAR ON LASER HARDENED

SURFACES WITHOUT OXIDES

Fig. 15 Overlap area - tribilogical trail, steel steel

1.2311, magnification 5x

Fig. 16 Hardened area - tribilogical trail, steel steel

1.2311, magnification 5x

In case of steel 1.2311 (Fig. 15 and 16) was

find out higher wear in overlap area. Despite of

higher wear confocal microscope wasn't able to

measure deepness of tribological trail (due to low

measurement sensitivity). Reason for low deepness

of tribological trails was in blocking trail by the

oxide layer, which protect surface from mass

losses.

Overlap has no influence on wear on

hardened surface of steel 1.2379. Just only in case

that orientation of tribological trail was orthogonal

to orientation grinding trails it leads to greater

demarcation borders of tribological trail.

Fig. 17 Overlap area - tribilogical trail, steel steel

1.2379, magnification 5

Fig. 18 Hardened area - tribilogical trail, steel steel

1.2379, magnification 5x

4. CONCLUSION

The aim of the experiment was to evaluate

influence oxide layer on wear process on tool steels

1.2311 and 1.2379. This report was especially

focused on wear analysis in overlap areas between

laser hardened trails and areas in center of the

hardened trails.

From the measurements emerges positive

contribution of oxide layer on wear process. Oxide

layer covers and protect surface from contact wear.

Gridded, laser hardened surface was more wear in

overlap areas. This areas was filled by products of

oxidation arisen during tribological test. It leads to

same deepness of tribological trail in every places.

Our measures shown, that overlap areas has

no influence on wear resistance on laser hardened

surfaces.

Acknowledgements

This article was created terms of project

Mobile laser workstation for treating steel - MPO-

OPPI - the pilot project of innovation action -

support of knowledge transfer. This project was

solved in cooperation with MATEX PM s.r.o. and

University of the west Bohemia in Pilsen (Faculty

of mechanical engineering - Materials Engineering

and Engineering Metallurgy).

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[5] Materiálový list ČSN 41 9573

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On-Disc, Metal 2005, Hradec Nad Moravicí

2005