The Comparison of the Effects of Nodular Cast Iron Laser Alloying with Selected Substances

Abstract

The aim of this research was to compare the effects of laser treatment, with the same heating conditions, using four selected alloying substances (silicon, cobalt, silicon nitride and titanium), in the surface layer of nodular cast iron. The treatment was performed with a molecular laser. As the microstructure observation revealed, the greatest amount of implemented elements was diluted during the treatment in a solid solution. In all cases (except during the alloying process with cobalt), in the alloying zone, a fine and homogeneous microstructure was found. In the alloying zone, cobalt counteracted the formation of the martensitic microstructure so effectively that austenite turned into exclusively fine perlite (or bainite at most). The size of the obtained alloyed zone was different, despite the same laser heat treatment parameters. A 30% smaller depth of zone after laser alloying with silicon nitride, as compared with alloying with cobalt or silicon, was observed. The highest strengthening of the alloyed zone could be expected when silicon (hardness was approx. 980HV0.1 and the modulus of elasticity was 208 GPa) and titanium (hardness was approx. 880HV0.1 and the modulus of elasticity was 194 GPa) were used. The lowest hardness (700HV0.1) was observed for the zone alloyed with cobalt due to pearlite (or bainite) existence.

The effect on wear resistance of laser alloying with chromium and titanium of grey iron parts

“…A nearly threefold increment in the hardness of the surface layer was noted. Fourfold growth in hardness after titanium incorporation into nodular iron was noticed in the author's previous own research [18] although XRD did not indicate TiC in the surface layer. Near the surface, locally, only TiN or Ti(N,C) were visible in the microstructure as a result of interaction with nitrogen from the atmosfere.…”

“…C The chromium as well as titanium was in the form of powder with a particle size of 325 mesh and 99.0% of purity. Those elements were chosen as the alloying elements for laser remelting also because of their ability to enrich the remelting zone during this treatment, which was confirmed during previous research [18,19] by EDS and AES analysis. After covering the surface, heating using a laser beam was conducted with a diode laser.…”

Laser Remelting of Ductile Cast Iron to Achieve a Graphite-Free Surface Layer for Enabling a Manual High-Gloss Finish

“…An approach to increase the hardness of GJS is laser heat treatment [7,8] or laser remelting [5,[9][10][11][12][13]. The laser remelting of metals involves the remelting of a thin surface layer, typically ranging from 1 to 100 µm, using laser radiation.…”

Properties of Laser-Alloyed Stainless Steel Coatings on the Surface of Gray Cast Iron Discs

“…The hardness and other properties of laser-alloyed coatings have also been investigated [26][27][28][29][30][31][32]. Paczkowska [26] reported that the hardness of Si coatings was higher than that of the Ti, SiN and Co coatings at more than 900 HV 0.1 . Lont et al [27] found that titanium coatings can improve the surface hardness and erosion resistance of ductile iron.…”