Surface improvement of 42CrMo4 low alloy steel via nitrocarburization and electroless Ni-P plating: enhancing the surface hardness

Authors : Uğur Temel Yıldız, Temel Varol, Burak Berk Day, Büşra Kandemir, Furkan Alptekin, Ahmet Fuat Günaçar

Pages : 18-21

View : 44 | Download : 53

Publication Date : 2024-06-30

Article Type : Research

Abstract :This investigation endeavors to enhance the surface characteristics of 42CrMo4 low alloy steel, a material of considerable prominence within the defense industry, and particularly in the context of handgun production. The augmentation is pursued through the implementation of nitrocarburization and electroless Ni-P plating processes. Commencing with 42CrMo4 steel samples characterized by an initial hardness of 303.4±12.3 HV0.1, the specimens underwent a meticulous nitrocarburization procedure. The resultant nitrocarburized surface was subject to characterization via microhardness measurements adhering to the DIN 50190 standard, revealing pertinent hardness and diffusion depth values of 566 HV0.1 and 132.60 µm, respectively. The electroless Ni-P plating was executed over a 45-minute duration at 90⁰C, employing proprietary chemicals. Post-plating, the samples underwent heat treatment at 250⁰C for durations of 4 and 8 hours, strategically designed to optimize the hardness of the electroless Ni-P plating. Coating thickness and microhardness assessments were conducted leveraging a metallurgical microscope and a Vickers hardness tester. Observed coating thicknesses ranged from 10.91 µm to 14.81 µm. The initial hardness of the electroless Ni-P plating, as measured, stood at 563±33 HV0.01. Subsequent heat treatments at 250⁰C for 4 and 8 hours resulted in an appreciable augmentation of the coating hardness to 715±24 HV0.01 and 852±42 HV0.01, respectively. In summation, the electroless Ni-P plating process manifested a notable elevation in the initial hardness of 42CrMo4 low alloy steel from 303.4±12.3 HV0.1 to 852±42 HV0.01 on the surface. Concurrently, the nitrocarburization process engendered a gradual decline in hardness from 566 HV0.1 to core hardness, spanning a distance of 132.60 µm from the surface. This symbiotic integration results in a composite structure characterized by a resilient and wear-resistant surface superimposed with a subsurface conducive to sustaining the hardened coating.
Keywords : Materials Science, Nitrocarburization, Electroless Ni-P Plating, Surface Hardness, Steel