Tuning of mechanical and structural properties of 20 MC 5 steel using N ion implantation and subsequent annealing

In the present work, effect of 50 keV nitrogen ion implantation on the structure and mechanical properties of as-implanted and annealed 20 MC 5 steel samples is investigated. XRD measurements confirmed the formation of alpha-FeN phase. The crystallite size and stress of the nitride samples is found to increase with the ion fluence. The calculated value of crystallite size and stress is similar to 29.21 nm and similar to 9.826 x 10(8) Pa, respectively, for 1 x 10(16) ions/cm(2) implanted sample. An increase in crystallite size (similar to 31.26 nm) and phase transformation from FeN phase to Fe2-3N and Fe4N phase is observed on annealing at 500 degrees C for 2 h. Atomic force microscopy results show that surface roughness and particle size are increasing with ion fluence. Mechanical properties studied using Micro-Vicker hardness tester showed that hardness of the annealed sample increases initially with ions fluences (similar to 8.4 GPa at 1 x 10(15) ions/cm(2)) and then it starts decreasing to similar to 4.66 GPa when sample is exposed to an ion fluence of 1 x 10(16), due to limited solubility of nitrogen in steel. Finally, we have performed simulations using TRIM software to investigate the impurity profile in the samples under the influence of 50 keV ions. Our results show that the ion implantation technique is very good tool for controlled modification of mechanical properties of 20 MC 5 steel, and it can be used in various applications such as crankshafts, gears, engines and machinery parts. (C) 2017 Elsevier B.V. All rights reserved.