Laser Surface Modification of Borochromizing C45 Steel

Abstract

In this study the test results for borochromized C45 steel after laser surface modification were presented. Influence of laser heat treatment on the microstructure and microhardness of surface layer was investigated. The process of borochromizing consisted of chromium plating followed by diffusion boronizing. The laser heat treatment (LHT) of multiple tracks in the helical line was carried out with CO 2 laser beam. The technological laser TRUMPF TLF 2600 Turbo CO 2 of the nominal power 2.6 kW was applied. Borochromizing was carried out with laser power density q = 41.40 kW/cm 2 and at laser beam scanning rate v = 0.67 m/min and v = 2.016 m/min. Measurements of microhardness were conducted using the Vickers' method and Zwick 3212 B hardness tester. Microstructure observations were performed by means of an optical microscope Metaval Carl Zeiss Jena and scanning electron microscope Tescan VEGA 5135. After laser heat treatment with re-melting a three-zone layer was obtained, which included: re-melted zone, heat affected zone and a core. Influence of laser treatment parameters on thickness of melted zone and microstructure of the surface layer was tested. The microhardness tested along the axis of track of the surface layer after laser modification was about 800-850 HV. The results of tests showed influence of laser power density and scanning rate on microstructure and properties of borochromized layers.Keywords: chromium plating, diffusion boriding, laser heat treatment, microstructure, microhardness W pracy przedstawiono wyniki badań borochromowanej stali C45 po laserowej modyfikacji. Badano wpływ laserowej obróbki cieplnej na mikrostrukturę i mikrotwardość warstwy wierzchniej. Proces borochromowania składał się z obróbki galwanicznej, następnie dyfuzyjnego borowania. Laserowa obróbka cieplna dla ścieżek wielokrotnych po linii śrubowej była wykonana przy użyciu lasera technologicznego CO 2 firmy TRUMPF TLF 2600 Turbo o mocy nominalnej 2,6 kW. Borochromowanie przeprowadzono przy użyciu gęstości mocy lasera q = 41,40 kW/cm 2 i prędkości skanowania wiązki laserowej v = 0,67 m/min oraz v = 2,016 m/min. Pomiar mikrotwardości wykonano metodą Vickersa na twardościomierzu Zwick 3212B. Natomiast badania mikrostruktury przeprowadzono przy użyciu mikroskopu Metaval produkcji Carl Zeiss Jena jak również skaningowego mikroskopu elektronowego Tescan VEGA 5135. Po laserowej obróbce cieplnej z przetopieniem otrzymana warstwa składała się z trzech stref: przetopionej, wpływu ciepła i rdzenia. Badano wpływ parametrów laserowej obróbki na grubość i mikrostrukturę strefy przetopionej. Mikrotwardość w osi ścieżki warstwy wierzchniej po laserowej modyfikacji wynosiła ok. 800-850 HV. Wyniki badań wykazały wpływ oddziaływania gęstości mocy lasera i prędkości posuwu na mikrostrukturę oraz właściwości warstw borochromowanych.

Microstructure, chemical composition, wear, and corrosion resistance of FeB–Fe2B–Fe3B surface layers produced on Vanadis-6 steel using CO2 laser

“…As a result of combination of several different technological processes, the layers are enriched in various chemical elements, which in final effect, gives the improvement of the operational properties. Increasing of wear and corrosion resistance, as well as reduction the brittleness of boronized layers can be obtained by modification of these layers using chromium [1,6,7], nickel [8][9][10], and copper [6]. To achieve this purpose, the diffusion methods [1,6,8]; laser methods (e.g., laser hardening [11][12][13], laser remelting [4,7,14], laser alloying [15][16][17], laser cladding [18][19][20][21]); as well as the electroplating [8][9][10] or thermal spraying methods [22] can be applied.…”

Microstructure, phase composition and corrosion resistance of Ni2O3 coatings produced using laser alloying method

“…The influence of a laser beam on the modification of a surface layer containing elements such as Cr [2], Si [3], C [4], N [5], Ni [6], Mo [7], has been analyzed by researchers in mentioned papers. Lasers are widely used in surface engineering.…”

“…The modification of surface layers has been discussed in numerous publications. The authors modify the layer by using the laser beam [1][2][3][4][5][6][7][9][10][11] as well as using the plasma jet [8,12].…”

“…Surface and heat treatment using a laser beam is advantageous because it results in beneficial microhardness, high wear resistance and good corrosion resistance [1-7, 9-11, 13]. The appropriate selection of the surface material and the treatment parameters lead to the extension of the life cycle of the product [1][2][3][4][5][6][7][8][9][10][11][12] In the paper [7] authors presented analysis of corrosion and wear resistance of NiTi surface after the modification by Mo and ZrO2 using a laser beam. The modified layers were free from microcracks and porosity.…”

“…B, C, N, Si, Cr, Ni, Mo) [1][2][3][4][5][6][7], intermetallic phases [8] or ceramic powders [7,9] enable shaping characteristics of materials, giving them new properties, including increased durability and reliability as well as corrosion resistance. The modification of surface layers has been discussed in numerous publications.…”