266 INŻYNIERIA MATERIAŁOWA MATERIALS ENGINEERING ROK XXXVIII

The influence of laser boronizing parameters on the mechanism of formation and properties of surface

layers produced on iron alloys with various carbon contentAleksandra Pertek-Owsianna1*, Karolina Wiśniewska1,2, Aneta Bartkowska2

1Faculty of Engineering, State University of Applied Science in Konin, Konin, Poland, 2Institute of Materials Science and Engineering, Poznan University of Technology, Poznan, Poland; *aleksandra.pertek-owsianna@konin.edu.pl

This paper analyses the boronizing treatment which was performed by means of CO2 molecular laser with a power of 2600 W. Boron was introduced by remelting the paste with a thickness of 40÷120 mm, containing amorphous boron or iron-boron, use the material of the substrate, such as Armco iron or C45 and C90 types of steel. The influence of the boron paste thickness, variable P power from P = 0.78 kW to 1.82 kW, with the constant laser beam scanning velocity v = 2.88 m/min and material type on the mechanism of formation, microstructure, microhardness and frictional wear resistance of the formed layers (surface structure). After laser boronizing the surface layer consists of zone-structured tracks: melted zone, heat affected zone and the substrate. The melted zone contains boride-martensitic eutectic, in C45 and C90 types of steel there under the remelted zone there is a heat affected zone which is composed of a martensitic structure. With the increase in the laser power, width and depth of laser tracks increases in all the iron alloys with variable thickness of the ap-plied amorphous boron paste. With the increase in the thickness of the boron paste, width of the laser tracks increases and depth of the laser tracks decreases with the constant beam power. The maximum dimensions of the remelted zone for C45 steel were: approx. 600 µm (width) and 350 µm (depth). The highest average microhardness of the surface layer reaches approx. 1500 HV0.1 and it decreases with the increase in power for all the iron alloys. Microhardness and frictional wear resistance of the layer boronized by means of laser with the use of the paste containing iron-boron is lower than that of the layer boronized with the use of the paste containing only boron.

Key words: laser boronizing, microstructure, microhardness, frictional wear resistance.

Inżynieria Materiałowa 6 (220) (2017) 266÷271DOI 10.15199/28.2017.6.3© Copyright SIGMA-NOT MATERIALS ENGINEERING

1. INTRODUCTION

Laser boronizing, which means alloying the substrate material with boron by means of a laser beam, is a technology which is being more and more commonly used in surface engineering thanks to developments in laser technology and the availability of lasers of newer and newer generation [1÷4]. Examples of research into the processes of alloying with various chemical elements, including bo-ron with the use of laser beam can be found in Polish and foreign publications as early as at the end of 20th century [1, 5÷7] as well as in contemporary papers [8÷25]. Amorphous boron is used for laser alloying most frequently [5, 7, 11, 12, 24], but there are also, other compounds and phases, such as iron-boron, boron oxide, bo-ron nitride, boron carbide or mixtures of these phases [6, 8÷10]. The alloying element can be introduced by means of paste which is applied beforehand or indirectly into material in the pool of the remelted substrate material.

The equipment applied in the process is most commonly used in the technology of cutting, boring, welding, thus CO2 molecular lasers [6, 7, 11, 12, 19], but also diode ones [10] or YAG type [5].

Laser treatment is an effective method because in case of quick heating and cooling there is an increase in properties of the treated material thanks to fine-grained microstructure that is formed in the surface layer, with newly produced metastable phases (after bo-ronizing it is phase Fe3B [16, 19]), their defects and large compres-sive stresses that emerge in the process [1, 2].

The structure and properties of boronized layers obtained by la-ser are comparable to those achieved after conventional diffusive boronizing [3, 4, 14, 15] or after the laser remelting of diffusive layers of iron borides [4, 25]. It is found that laser boronizing can be an alternative to diffusive processes because it produces surface layers with similar microhardness and frictional wear resistance [14, 17, 20, 22], with lower brittleness, better cohesion, good low-cycle fatigue strength [19] and corrosion resistance [21]. Trial tests were conducted with the aim of applying laser-boronized layers on

machinery parts, including the elements of friction pairs in engines working with bearing steels [11], crankshaft pins made of spheroi-dal graphite cast iron [12, 13], piston pins made of low-alloy steel [24]. Some of the advantages of laser technology include its eco-friendliness and the possibility of perform local surface treatments.

In their publications to-date, the authors of this paper have exam-ined numerous factors influencing the results of laser alloying with boron [18, 19], namely, the structure, microhardness, brittleness, adhesion, tribological and anticorrosive properties of the obtained surface layers on the substrate of C45, 41Cr4 constructional steel [18, 19] as well as that of high strength steel with Hardox-type or boron B27 steel [23].

The purpose of the research presented in this paper is to sum-marize and generalize the results of the tests with the use of CO2 laser, and it is concerned with establishing the influence of carbon content in the Fe alloy and the treatment parameters, such as laser power, thickness and type of the alloying paste, on the mechanism of development, structure and thickness of the surface layer, its mi-crostructure, microhardness and tribological properties.

2. EXPERIMENTAL

The tests were carried out on the samples of Armco iron, C45 and C90 types of steels. The chemical composition of the materials is shown in Table 1. The samples were ring-shaped with the following dimensions: 20 mm in external diameter, 12 mm in internal diam-eter and 12 mm in height.

Before boronizing, the samples of C45 steel to be tested for fric-tional wear resistance were hardened from austenitization tempera-ture of 850°C in water and then tempered at 560°C for l hour.

For the laser heat treatment (LHT), a technological laser TRUMPF TLF 2600 Turbo CO2 with the nominal power 2.6 kW was used. The above mentioned laser is located at Laser Technology Laboratory of Mechanical Technology Institute of Poznan Technical University. Before proceeding with the laser heat treatment (LHT),

NR 6/2017 INŻYNIERIA MATERIAŁOWA MATERIALS ENGINEERING 267

amorphous boron or iron-boron with water glass and distilled water in the form of paste with a thickness of approx. 40, 80 and 120 µm was applied. Then, the samples were subject to laser irradiation with the power P = 30, 40, 50 and 70%, that is, P = 0.78, 1.04, 1.3, 1.82 kW, which corresponds to density q respectively: 24.84, 33.12, 41.40, 57.96 kW/cm2, with the constant laser beam scanning veloc-ity v = 2.88 m/min, at a constant beam diameter d = 2 mm, for the obtained single tracks. Earlier tests by the author of this paper [18, 19], which were performed within the range of v = 0.67÷5.76 m/min showed that with the increase in v, there is an increase in mi-crohardness of the remelted zone, but, at the same time, the depth of the tracks decreases, and that is why the selected v = 2.88 m/min is one of the most optimal scanning velocity. For the tests of fric-tional wear, a cylindrical friction surface was covered with multiple tracks with the use of iron-boron paste with a thickness of 40 µm at the constant power P = 1.04 kW with the distance between tracks f = 0.50 mm. The results of tribological tests were compared with those obtained for boron paste in the same conditions [18].

The observation of microstructure was made by the Metaval light microscope produced by Carl Zeiss Jena and equipped with Moticam camera.

The microhardness measurements of the samples were carried out by the Vickers method using ZWICK 3212 B microhardness tester under a load of 100 G (HV0.1).

The tests of resistance to frictional wear were carried out using a tribometer MBT-01 type AMSLER with the following settings: the sample — a rotating ring/plate and the counter-sample — sintered carbide S20S with a hardness of 1430 HV0.1. The wear resistance tests were made under a constant load of F = 147 N and at a sample rotation speed of v = 0.26 m/s (n = 250 rpm). Wear resistance was determined on the basis of the wear intensity coefficient calculat-ing the value of Iw from the following correlation: Iw = (Δm/S·t), mg/cm2·h, where: Dm – mass loss, mg, S – a friction surface, cm2, t – friction time, h.

Table 1. Chemical composition of Fe alloys, wt %Tabela 1. Skład chemiczny stopów Fe, % mas.

Fe alloys C Mn Si P S

Fe Armco 0.05 0.20 0.21 0.021 0.025

C45 steel 0.46 0.55 0.25 0.04 0.03

C90 steel 0.96 0.31 0.21 0.017 0.02

Fig. 1. Microstructure of laser-borided Fe Armco sample (a), C90 steel (b); an image of one track; LHT: P = 1.04 kW; boron paste of 40 μm thickness; 1 – MZ (remelted zone), 2 – HAZ (heat affected zone), 3 – substrate Rys. 1. Mikrostruktura po laserowym borowaniu próbki Fe Armco (a), stal C90 (b); widok pojedynczej ścieżki; LOC: P = 1.04 kW; pasta boru o gru-bości 40 μm; 1 – SP (strefa przetopiona), 2 – SWC (strefa wpływu ciepła), 3 – podłoże

3. RESULTS AND DISCUSSION

The results of the tests aimed at examining the microstructure of laser-boronized layers formed on Armco iron and C45, C90 types of steels are shown in Figures 1, 2. After boronizing the steel, the layer is consisting of the following zones: the remelted zone (MZ) and the heat affected zone (HAZ), under within there is the base ma-terials. The microstructure of the melted zone consists of eutectics, with a mixture of iron borides and martensite of highly fine-grained microstructure, and the heat affected zone demonstrates a marten-sitic structure [18, 19]. There is only a melted zone on Armco iron (Fig. 1a).

The dimensions of the laser tracks depend on the parameters of the treatment, namely, laser beam power and the amount of the al-loyed boron. Width a and depth b of the melted zone increase with the increase in the laser power (Fig. 3, 4).

Regardless of the iron base, the depth of the melted zone (MZ) increases from approx. 50 μm to approx. 350 μm along the axis of the laser tracks, and the width from approx. 520÷620 μm. The low-est power of 0.78 kW produces thin, hard and porous layers, which are not discussed any further in this paper. With the increase in the thickness of the boron paste, at the constant power level, the width of tracks a increases up from approx. 500 to 600 μm, and the depth b decreases from approx. 180 to 100 μm (Fig. 5, 6) for C45 steel. For the remeining materials there are similar correlations. Heat af-fected zones for the tested types of steels have similar dimensions — approx. 100 μm (Fig. 1b, 2a).

The results of measurements aimed to determine the microhard-ness of iron alloys after the laser boronizing are shown in Figures 7÷9. As Figure 7 indicates, for C45 steel, with the increase in the power of laser, microhardness gradually decreases to approx. 1500÷1000 HV0.1 in the melted zone, through 600÷800 HV0.1 in the heat affected zone to approx. 220 HV0.1 in the substrate of the steel. As result of the rapid mixing of melted boron with iron and carbon in the substrate, after solidification there might occur an non-uniform distribution of boron [4, 7, 25], which causes a disper-sion in hardness within the depth of the track. This phenomenon was confirmed by the test results found in other papers [10, 19]. For further tests, the calculated average values of microhardness were adopted for the melted zone. Figure 8 shows the results of mi-crohardness measurements for alloys with various carbon content and various thickness of the boron paste. As the obtained correla-tions indicate, average microhardness in the melted zone decreases along with the laser power from approx. 1500 HV0.1 for the pow-er of 1.04 kW to approx. 1000 HV0.1 for the power of 1.82 kW.

268 INŻYNIERIA MATERIAŁOWA MATERIALS ENGINEERING ROK XXXVIII

Fig. 2. Microstructure of laser-borided C45 steel with the use of: a) boron paste of 40 μm thickness, an image of one track, b) iron–boron paste of 40 μm thickness, an image of multiple tracks; LHT: P = 1.04 kWRys. 2. Mikrostruktura stali C45 po borowaniu laserowym z użyciem: a) pasty boru o grubości 40 µm, widok pojedynczej ścieżki SP, b) pasty Fe–B o grubości 40 μm, widok wielokrotnej ścieżki SP; LOC: P = 1.04 kW

Fig. 3. Influence of laser power P and boron paste layers B thickness on the width a of a single melted trackRys. 3. Wpływ mocy lasera P i grubości warstwy pasty boru B na szero-kość a pojedynczej ścieżki przetopionej

Fig. 4. Influence of laser power P and boron paste layers B thickness on the depth b of a single melted trackRys. 4. Wpływ mocy lasera P i grubości warstwy pasty boru B na głębo-kość b pojedynczej ścieżki przetopionej

Fig. 5. Influence of boron paste layers B thickness and type of Fe alloys on the width a of one melted trackRys. 5. Wpływ grubości warstwy pasty boru B i rodzaju stopu Fe na sze-rokość a pojedynczej ścieżki przetopionej

Fig. 6. Influence of boron paste layers B thickness and type of Fe alloys on the depth b of one melted trackRys. 6. Wpływ grubości warstwy pasty boru B i rodzaju stopu Fe na głę-bokość b pojedynczej ścieżki przetopionej

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The thickness of the boron paste layers and the type of steel base materials influence the average microhardness of the surface layer in an ambiguous way.

Tests were carried out to examine the process of the laser bo-ronizing of C45 steel with the use of the paste containing (Fe–B)iron-boron. On the basis of the test results presented in this paper and the author’s own earlier tests, aimed to examine the process of boronizing with the use of paste containing boron [17÷19], the advantageous parameters from the technological and economic standpoint were applied and they are as follows: paste layer with a thickness of 40 μm, average laser power P = 1.04 kW, laser beam scanning velocity v = 2.88 m/min, distance between the laser tracks f = 0.5 mm. With these parameters applied, multiple tracks with approx. 50% of overlapping were formed, with a maximum thick-ness of approx. 120÷150 μm in the axis, and their microstructure for C45 steel is shown in Figure 2b. For comparison, with the same conditions LHT and on the same C45 steel, but boron-alloyed, tracks with similar thickness, adjoining each other, with a micro-

hardness in the axis of the melted track approx. 1200 HV0.1 are obtained [18]. The profiles of microhardness after laser boronizing with iron-boron paste (Fig. 9) indicate that the microhardness in the melted zone is approx. 700÷800 HV0.1, in the heat affected zone 400÷600 HV0.1, and in the substrate approx. 350 HV0.1. The samples with the microstructure and microhardness from Figure 9, presented in Figure 2b, were subjected to frictional wear resistance tests, whose results are shown in Figure 10. From the tests it ap-pears that after a period of running in the surface, it shows linear wear. The determined wear intensity coefficient Iw is higher than the one calculated for the constructional steels which was laser-alloyed with the use of boron paste as well as for the steel which was diffusion boronized (Tab. 2).

4. CONCLUSIONS

The tests and analysis of laser boronizing treatment of Fe Armco, C45 and C90 steels by means of CO2 molecular laser with a power

Fig. 7. Microhardness profiles of laser-borided C45 steel of one track for different power P and 40 μm boron paste layer thickness Rys. 7. Profile mikrotwardości po borowaniu laserowym stali C45 w po-jedynczej ścieżce dla różnej mocy P i grubości warstwy pasty boru 40 μm

Fig. 8. Influence of power P and boron paste layer thickness on micro-hardness of laser-borided: Fe Armco, C45 and C90 steelsRys. 8. Wpływ mocy i grubości warstwy pasty boru na mikrotwardość warstw borowanych laserowo: żelazo Armco, stale C45 i C90

Fig. 9. Microhardness profiles of laser-borided C45 steel on multiple track for power P = 1.04 kW and the thickness of iron–boron paste layer of 40 μm; 1 – along the axis of the track, 2, 3 – along the contact of tracksRys. 9. Profile mikrotwardości po borowaniu laserowym stali C45 w ścieżce wielokrotnej dla mocy P = 1.04 kW i warstwy pasty żelazo–bor o grubości 40 μm; 1 – wzdłuż osi ścieżki, 2, 3 – wzdłuż styku ścieżek

Fig. 10. Frictional wear resistance of C45 steel after laser boriding with the use of iron–boron paste layer of 40 μm thickness and laser power P = 1.04 kW; multiple tracks distance f = 0.5 mmRys. 10. Odporność na zużycie przez tarcie borowanej laserowo stali C45 z użyciem pasty żelazo–bor o grubości warstwy 40 μm oraz mocy lasera P = 1.04 kW; odległość między ścieżkami f = 0,5 mm

270 INŻYNIERIA MATERIAŁOWA MATERIALS ENGINEERING ROK XXXVIII

of 2600 W made it possible to formulate conclusions of utilitar-ian importance.1. During the process of alloying with the use of paste containing

boron, the most advantageous results are obtained for the medi-um laser power within the range of 40÷50%, namely 1÷1.3 kW.

2. The obtained surface layers, independent of carbon content in the substrate of the iron alloy, for the constant power 1.04 kW, demonstrate large dimensions of the melted tracks: from approx. 180 μm (depth) and to 600 μm (width), high microhardness ap-prox. 1500 HV0.1, similar to the microhardness of the layers which were diffusion boronized. The martensitic heat affected zone for both types of steels reaches a thickness of approx. 100 μm and microhardness of 600÷800 HV0.1.

3. For lower laser powers than the ones mentioned above, thin, hard and brittle melted zones are obtained, and for higher laser powers the dimensions of the tracks increase, but microhardness decreases to approx. 1000 HV0.1.

4. The effects of the thickness of the alloying paste on the micro-hardness is not clearly visible. It only influences the dimensions of laser tracks. At higher thickness of alloying paste layer, the width of tracks increases, whereas their depth decreases.

5. The surface layer of Fe Armco can be considerably hardened, up to approx. 1400 HV0.1, with the use of boron alloying.

6. C45 steel which was laser boronized with the use of paste con-taining amorphous boron demonstrates more advantageous properties. The microhardness of the steel in the melted zone reaches approx. 1300 HV0.1 [18], and for alloying with the use of iron–boron paste, approx. 800 HV0.1. The frictional wear re-sistance after alloying with iron-boron is also lower (Tab. 2).

ACKNOWLEDGEMENTS

The authors would like to express thanks for cooperation during laser treatment to the following people: prof. Mieczysław Kawa-lec, Dr. Marian Jankowiak, Dr. Damian Przestacki and Mr. Ireneusz

Nowak from Institute of Mechanical Technology, Poznan Univer-sity of Technology.

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Table 2. The results of frictional wear resistance testsTabela 2. Wyniki badań odporności na zużycie przez tarcie

Steels Parameters of treatment

Iw mg/(cm2∙h)

Typeof boriding Literature

C45

LHT:P = 1.04 kW

v = 2.88 m/minf = 0.5 mm

1.72 laser boriding with iron–boron paste this paper

C45

LHT:P = 1.04 kW

v = 2.88 m/minf = 0.5 mm

1.37laser boriding with amorphous boron

paste[18]

41Cr4

LHT:P = 1.17 kW

v = 3.84 m/minf = 0.5 mm

1.40laser boriding with amorphous boron

paste[19]

C4541Cr4

temp. 950°Ctime 4 h 1.47

gas-contacte diffusion boriding with amorphous

boron

[20]

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Wpływ parametrów borowania laserowego na mechanizm tworzenia i właściwości warstw wierzchnich otrzymanych

na stopach żelaza o zróżnicowanej zawartości węglaAleksandra Pertek-Owsianna1*, Karolina Wiśniewska1,2, Aneta Bartkowska2

1Wydział Społeczno-Techniczny, Państwowa Wyższa Szkoła Zawodowa w Koninie, 2Instytut Inżynierii Materiałowej, Politechnika Poznańska, *aleksandra.pertek-owsianna@konin.edu.pl.

Inżynieria Materiałowa 6 (220) (2017) 266÷271DOI 10.15199/28.2017.6.3© Copyright SIGMA-NOT MATERIALS ENGINEERING

Słowa kluczowe: borowanie laserowe, mikrostruktura, mikrotwardość, odporność na zużycie przez tarcie..

1. CEL PRACY

W pracy przeanalizowano mechanizm procesu borowania z uży-ciem lasera molekularnego TRUMPF TLF 2600 Turbo CO2. Bor wprowadzano przez przetopienie laserem pasty zawierającej bor z materiałem podłoża w postaci żelaza Armco oraz stali C45 i C90. Badania miały na celu określenie wpływu zawartości węgla w sto-pie żelaza oraz parametrów obróbki (moc lasera, prędkość posuwu wiązki, rodzaj i grubość warstwy pasty borującej) na mikrostruktu-rę, mikrotwardość oraz odporność na zużycie przez tarcie wytwo-rzonej warstwy wierzchniej.

2. MATERIAŁ I METODYKA BADAŃ

Badania przeprowadzono na próbkach w kształcie pierścienia o składzie chemicznym przedstawionym w tabeli 1. Zastosowano pastę borującą o grubości ok. 40, 80 i 120 µm zawierającą bor amor-ficzny lub żelazo–bor. Do badań użyto laser o mocy P = 0,78; 1,04; 1,3; 1,82 kW, stałej prędkości skanowania wiązką v = 2,88 m/min i średnicy wiązki d = 2 mm. Próby zużycia przez tarcie przepro-wadzono na pokrytych wielokrotnymi ścieżkami powierzchniach cylindrycznych, otrzymanych przy stałej mocy P = 1,04 kW, odle-głości między ścieżkami f = 0,50 mm, z użyciem pasty borującej o grubości 40 µm. Przed procesem borowania próbki poddano ulep-szaniu cieplnemu.

Obserwacji mikrostruktury dokonano za pomocą mikroskopu świetlnego Metaval produkcji Carl Zeiss Jena wyposażonego w ka-merę Moticam. Pomiary mikrotwardości wykonano sposobem Vic-kersa HV0,1 z zastosowaniem mikrotwardościomierza typu Zwick 3212B. Badania odporności na zużycie przez tarcie przeprowa-dzono za pomocą tribometru MBT-01 typu AMSLER w układzie: próbka (obracający się pierścień)–przeciwpróbka (płytka z węglika spiekanego S20S o twardości 1430 HV). Określono zużycie przez tarcie na podstawie wskaźnika intensywności zużycia Iw = (Δm/S·t), mg/cm2·h, gdzie: Dm – ubytek masy, mg, S – powierzchnia tarcia, cm2, t – czas tarcia, h.

3. WYNIKI I ICH DYSKUSJA

Warstwa wierzchnia po borowaniu laserowym charakteryzuje się ścieżkami składającymi się ze strefy przetopionej SP, strefy wpły-wu ciepła SWC oraz rdzenia. Wyniki badań mikrostruktury warstw wytworzonych na żelazie Armco i stalach C45, C90 przedstawiono na rys. 1, 2. W strefie przetopionej występuje eutektyka borkowo-

-martenzytyczna, a poniżej w stalach C45 i C90 znajduje się strefa wpływu ciepła o strukturze martenzytycznej.

Wymiary ścieżek laserowych zależą od parametrów obróbki: mocy wiązki lasera oraz grubości warstwy pasty. Ze wzrostem mocy rośnie szerokość a oraz głębokość b strefy przetopionej dla wszystkich stopów żelaza i różnych grubości warstwy pasty boru amorficznego (rys. 3÷6), osiągając maksymalne wymiary: ok. 600 μm (szerokość) i ok. 350 μm (głębokość) dla stali C45. Wraz ze wzrostem grubości warstwy pasty, przy stałej mocy 1,04 kW, sze-rokość ścieżek zwiększa się od ok. 400 do ok. 600 μm, a głębokość maleje od ok.180 do ok. 100 μm (rys. 5, 6) dla stali C45. Pozostałe materiały wykazują podobne zależności.

Dla najmniejszej mocy lasera P = 0,78 kW otrzymuje się cienkie i porowate warstwy wierzchnie, które nie mają praktycznego zna-czenia. Wraz ze wzrostem mocy średnia mikrotwardość warstwy w strefie przetopienia maleje od ok. 1500 HV0,1 do ok. 1000 HV0,1 dla wszystkich stopów żelaza (rys. 7, 8). Martenzytyczna strefa wpływu ciepła dla obu badanych stali osiąga grubość ok. 100 μm (rys. 1b, 2a, b) i mikrotwardość 600÷800 HV0,1 (rys. 7, 9).

Stale po borowaniu z udziałem pasty żelazo–bor mają gorsze właściwości. Stal C45 borowaną laserowo z użyciem pasty za-wierającej bor amorficzny charakteryzuje mikrotwardość w strefie przetopionej ok. 1300 HV0,1 (rys. 7), a po stopowaniu żelazo–bo-rem ok. 800 HV0,1 (rys. 9). Odporność na zużycie przez tarcie stali borowanej pastą zawierającą żelazo–bor jest również mniejsza (rys. 10, tab. 2).

4. PODSUMOWANIE

Przeprowadzone badania i analiza procesu borowania żelaza Arm-co, stali C45 i C90 z użyciem lasera CO2 o mocy 2600 W pozwoliły na wytypowanie najkorzystniejszych z punktu widzenia technicz-nego i ekonomicznego parametrów procesu. Dla stopowania pastą o grubości ok. 40 μm zawierającą bor amorficzny jest to moc lasera w zakresie 1÷1,3 kW. Otrzymane warstwy wierzchnie niezależnie od zawartości węgla w podłożu stopu żelaza osiągają duże wymiary ścieżek przetopionych: głębokość do ok. 180 μm i szerokość do ok. 600 μm, dużą mikrotwardość ok. 1500 HV0,1, podobną do warstw borowanych dyfuzyjnie. Wzrost grubości warstwy pasty borującej nie wywiera jednoznacznego wpływu na zwiększenie twardości, jedynie szerokość ścieżek rośnie, a ich głębokość maleje. Warstwy borowane laserowo otrzymane z użyciem pasty zawierającej żela-zo–bor mają mniejszą twardość i odporność na zużycie przez tarcie od uzyskanych z zastosowaniem boru amorficznego.