Hardening and Roughness Reduction of Carbon Steel by Laser Polishing
Abstract
Laser polishing (LP) is a non-contact method to smooth surfaces. Its benefits are a fast and automated surface modification. The high-quality tempered steel 1.7225 refined by electro-slag remold is investigated. Laser polishing studies were carried out with a shielding gas enclosure to ensure an oxidation free condition. The roughness of the initial and laser polished surface have been determined by microscopy, roughness spectroscopy and white light interferometry (WLI). Finite element method (FEM) simulation is carried out to determine the heating and cooling rates of the steel surface. Scanning electron microcopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) has been used to analyze irregularities on the treated surface. The results show an overall roughness reduction by laser remelting by 47 % from Rz,i = 5.42 to Rz,f = 2.87 µm. Roughness spectroscopy results show smooth, polished surface with values of Rz = 0.5 µm for wavelengths smaller than 100 µm. At wavelengths above 200 µm the surface structure is dominated by a few small craters. The composition inside the craters has been analyzed. SEM results show small droplets inside the irregularities. EDX analysis of the impurities indicates a composition comparable to slag. The slag might origin from the electro slag remold process during steel production.
Keywords
Laser polishing Laser remold Electro slag remold steel Surface hardening Laser gradingReferences
- 1.Hafiz, A.M.K., Bordatchev, E.V., Tutunea-Fatan, R.O.: Influence of Overlap Between the Laser Beam Tracks on Surface Quality in Laser Polishing of AISI H13 Tool Steel. J. Manuf. Process. 14, 425–434 (2012)CrossRefGoogle Scholar
- 2.Pfefferkorn, F.E., Duffie, N.A., Li, X., Vadali, M., Ma, C.: Improving surface finish in pulsed laser micro polishing using thermocapillary flow. CIRP Ann.—Manuf. Tech. 62(1), 203–205 (2013)Google Scholar
- 3.Ukar, E., Lamikiz, A., de López Lacalle, L.N., del Pozo, D., Arana, J.L.: Laser polishing of tool steel with CO2 laser and high-power diode laser. Int. J. Mach. Tools Manuf. 50, 115–125 (2010)CrossRefGoogle Scholar
- 4.Kiedrowski, T.: Oberflächenstrukturbildung beim Laserstrahlpolieren von Stahlwerkstoffen. Shaker, Aachen (2009)Google Scholar
- 5.Liebing, C.: Beeinflussung funktioneller Oberflächeneigenschaften von Stahlwerkstoffen durch Laserpolieren, Aachen Techn Hochsch (2010)Google Scholar
- 6.Willenborg, E.: Polieren von Werkzeugstählen mit Laserstrahlung—Berichte aus der Lasertechnik. Shaker, Aachen (2006)Google Scholar
- 7.Willenborg, E.: Polishing with laser radiation. In: Poprawe, R. (ed.) Tailored Light 2—Laser Application Technology. Springer, Berlin (2011)Google Scholar
- 8.Kac, S., Kusinski, J.: SEM structure and properties of ASP2060 steel after laser melting. In: Proceedings of Symposium G on Protective Coatings and Thin Films-03 of the E-MRS 2003 Spring Conference: 180–181 and 611–615 (2004)Google Scholar
- 9.Martínez, S., Lamikiz, A., Tabernero, I., Ukar, E.: Laser Hardening Process with 2D Scanning Optics. Laser Assist. Net Shape Eng. 6 Proc. LANE 2010 Part 2, 39, 309–317 (2012)Google Scholar
- 10.Avilés, R., Albizuri, J., Lamikiz, A., Ukar, E., Avilés, A.: Influence of laser polishing on the high cycle fatigue strength of medium carbon AISI 1045 steel. Int. J. Fatigue 33, 1477–1489 (2011)CrossRefGoogle Scholar
- 11.Giesserei Lexikon, http://www.giessereilexikon.com/index.php?option=com_content&view=article&id=1157%3Aschlacke&catid=19%3As&lang=de Accessed 30 Oct 2013