Effect of laser heat treatment parameters on the microstructure and hardness of gas-nitrided layers

• Autorzy: Kulka M. , Panfil D. , Michalski J. , Wach P.

Identyfikatory

DOI

10.15199/28.2016.6.9

Warianty tytułu

PL

Wpływ parametrów laserowej obróbki cieplnej na mikrostrukturę i twardość warstw azotowanych gazowo

• Języki publikacji: EN

Abstrakty

EN

Nitriding is commonly used method of thermochemical treatment in order to produce surface layers of improved hardness and wear resistance. Using a gas nitriding with changeable nitriding potential, a nitrogen concentration at the surface could be controlled, influencing the phase composition and the growth kinetics of the layer. In this study, the hybrid surface treatment was applied. It consisted in gas nitriding and laser heat treatment (LHT) of 42CrMo4 steel. Two nitriding processes were carried out using changeable nitriding potential. Parameters on first process were as follows: temperature 570°C (843 K), time 4 h. The second process was performed at lower temperature 520°C (793 K) and longer duration 10 h. This resulted in various depths of the compound zone at the surface (20 and 8 μm, respectively). Next, the nitrided layers were laser heat-treated using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as the single tracks with various scanning rates (vl = 2.88 m/min and vl = 3.84 m/min). The laser beam power (P) ranged from 0.26 to 0.91 kW. The effects of the depth of compound zone as well as LHT parameters on the microstructure, dimensions and microhardness of laser tracks were analysed. In the majority of the produced laser tracks, remelted (MZ) and heat-affected (HAZ) zones were easily identified. Different microstructure was visible at low laser beam power (0.26 kW). The dimensions of MZ were limited, whereas the HAZ was clearly observed. The compound zone was still visible at the surface. Only the porous ε nitrides were slightly melted. Hardness increased significantly after LHT with complete and partial remelting of compound zone. Laser beam power and scanning rate influenced the depth and width of MZ and HAZ, so the thickness of hardened zone. The greater laser beam power or the smaller scanning rate, the larger hardened zone was observed.

PL

Azotowanie jest jedną z najpopularniejszych metod obróbki cieplno- chemicznej prowadzącą do wytwarzania warstw powierzchniowych o dużej twardości i odporności na zużycie. Stosując odpowiedni proces azotowania gazowego (ze zmiennym potencjałem azotowym), można kontrolować stężenie azotu na powierzchni, wpływając na kinetykę wzrostu strefy związków (azotków) oraz strefy dyfuzyjnej. Celem pracy była modyfikacja warstwy azotowanej za pomocą laserowej obróbki cieplnej. Badano wpływ parametrów laserowej obróbki cieplnej (mocy wiązki laserowej i szybkości skanowania) oraz grubości wytworzonej w wyniku azotowania strefy związków (azotków żelaza) na mikrostrukturę i twardość.

Słowa kluczowe

EN

gas nitriding; laser heat treatment; microstructure; hardness

PL

azotowanie gazowe; laserowa obróbka cieplna; mikrostruktura; twardość

• Wydawca: Wydawnictwo SIGMA-NOT
• Czasopismo: Inżynieria Materiałowa
• Rocznik: 2016
• Tom: Vol. 37, nr 6
• Strony: 328--334
• Opis fizyczny: Bibilogr. 21 poz., fig., tab.

Twórcy

autor

Kulka M.

• Instytut Inżynierii Materiałowej Politechniki Poznańskiej

autor

Panfil D.

• Instytut Inżynierii Materiałowej Politechniki Poznańskiej

autor

Michalski J.

• Instytut Mechaniki Precyzyjnej w Warszawie

autor

Wach P.

• 2Instytut Mechaniki Precyzyjnej w Warszawie

Bibliografia

• [1] Major B.: Chapter 7: Laser processing for surface modification by remelting and alloying of metallic systems in “Materials Surface Processing by Directed Energy Techniques”. Edited by Yves Paleau, Elsevier (2006).
• [2] Bojinović M., Mole N., Štok B.: A computer simulation study of the effects of tempearture change rate on austenite kinetic in laser hardening. Surface & Coatings Technology 273 (2015) 60÷76.
• [3] Safdar S., Li L., Sheikh M. A., Liu Z.: An analysis of the effect of laser beam geometry on laser transformation hardening. Journal of Manufacturing Science and Engineering 128 (2006) 659÷667.
• [4] Steen P. H., Ehrhard P., Schussler A.: Depth of melt-pool and heat-affected zone in laser surface treatments. Metallurgical and Materials Transactions A 25A (1994) 427÷435.
• [5] Sun P., Li S., Yu G., He X., Zheng C., Ning W.: Laser surface hardening of 42CrMo cast steel for obtaining a wide and uniform hardened layer by shaped beams. Int. J. Adv. Manuf. Technol. 70 (2014) 787÷796.
• [6] Mittemeijer E. J.: Fundamentals of nitriding and nitrocarburizing. In: Dossett J., Totten G. E., editors. ASM Handbook: Steel heat treating fundamentals and processes, Volume 4A, ASM International, Materials Park, OH (2013) 619÷646.
• [7] Roliński E.: Plasma-assisted nitriding and nitrocarburizing of steel and other ferrous alloys. In: Mittemeijer E. J., Somers M. A. J., editors. Thermochemical surface engineering of steels improving materials performance, Woodhead Publishing Series in Metals and Surface Engineering, Number 62, Elsevier (2015) 413÷457.
• [8] Conci M. D., Bozzi A. C., Franco A. R. Jr.: Effect of plasma nitriding potential on tribological behaviour of AISI D2 cold-worked steel. Wear 317 (2014) 188÷193.
• [9] Ogórek M., Skuza Z., Frączek T.: The efficiency of ion nitriding of austenitic stainless steel 304 using the “Active screen”. Metalurgija 54 (1) (2015) 147÷150.
• [10] Frączek T., Olejnik M., Tokarz A.: Evaluation of plasma nitriding efficiency of titanium alloys for medical applications. Metalurgija 48 (2) (2009) 83÷86.
• [11] Borowski T., Brojanowska A., Kost M., Garbacz H., Wierzchoń T.: Modifying the properties of the Inconel 625 nickel alloy by glow discharge assisted nitriding. Vacuum 83 (2009) 1489÷1493.
• [12] Yan M. F., Wang Y. X., Chen X. T., Guo L. X., Zhang C. S., You Y., Bai B., Chen L., Long Z., Li R. W.: Laser quenching of plasma nitrided 30CrMn- SiA steel. Material and Design 58 (2014) 154÷160.
• [13] Michalski J., Wach P., Tacikowski J., Betiuk M., Burdyński K., Kowalski S., Nakonieczny A.: Contemporary industrial application of nitriding and its modifications. Materials and Manufacturing Processes 24 (2009) 855÷858.
• [14] Sommers M., Mittemeijer E. J.: Layer-growth kinetics on gaseous nitriding of pure iron: evolution of diffusion coefficients for nitrogen in iron nitrides. Metallurgical and Materials Transactions A 26 (1995) 57÷74.
• [15] Małdziński L., Tacikowski J.: ZeroFlow gas nitriding of steels. In: Mittemeijer E. J., Somers M. A. J., editors. Thermochemical surface engineering of steels improving materials performance, Woodhead Publishing Series in Metals and Surface Engineering, Number 62, Elsevier (2015) 459÷483.
• [16] Michalski J., Tacikowski J., Wach P., Ratajski J.: Controlled gas nitriding of 40 HM and 38 HMJ steel grades with and without the surface compound layer, composed of iron nitrides. Maintenance Problems 2 (2006) 43÷52.
• [17] Schwartz B., Goehring H., Meka S. R., Schacherl R. E., Mittemeijer E. J.: Pore formation upon nitriding iron and iron-based alloys: The role of alloying elements and grain boundaries. Metallurgical and Materials Transactions A 45A (2014) 6173÷6186.
• [18] Kula P., Wołowiec E., Pietrasik R., Dybowski K., Januszewicz B.: Non-steady state approach to the vacuum nitriding for tools. Vacuum 88 (1) (2013) 1÷7.
• [19] Wołowiec E., Kula P., Januszewicz B., Korecki M.: Mathematical modelling the low-pressure nitriding process. Applied Mechanics and Materials 421 (2013) 377÷383.
• [20] Kulka M., Michalski J., Panfil D., Wach P.: Laser heat treatment of gasnitrided layer produced on 42CrMo4 steel. Inżynieria Materiałowa 5 (207) (2015) 301÷305.
• [21] Kulka M., Panfil D., Michalski J., Wach P.: The effects of laser surface modification on the microstructure and properties of gas-nitrided 42CrMo4 steel. Optics & Laser Technology 82 (2016) 203÷219.

Uwagi

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę.