The Diffusion Coatings for Industrial Tool Application

Abstract

The diffusion boriding process allows increasing the abrasion and corrosion resistance of the majority of steel grades. The aim of this study was to determine the influence of the chemical composition of the substrate of various steel grades on the microstructure of boride coatings produced using two diffusion methods: pack cementation boriding using EKABOR-2 and paste-pack boriding using EKABOR-PASTE on the substrate of tool and structural steels:. The boriding processes were carried out at 1000 o C in an argon atmosphere for 4h. Microstructural investigations of the obtained coatings indicate that a high content of alloying elements increasing the FeB (Cr, Mo, W) phase, results in the formation of an external, continuous layer of FeB borides. It was found that with increasing alloying element and carbon concentration, the total thickness of the boride coatings decreases. In particular, chromium content below about 1%, with a carbon content below about 0.4%, significantly limits or prevents the formation of the FeB phase. Increasing the content of alloying elements and carbon, results in a change in the morphology of the iron borides.

Study on the Tribological Properties of DIN 16MnCr5 Steel after Duplex Gas-Nitriding and Pack Boriding

“…Conversely, gas-nitriding and pack boriding showed greater wear resistance compared to the quenched and tempered DIN 16MnCr5 steel, resulting in reduced volumetric wear. This behavior aligns with findings in the literature, attributing the wear resistance to hardened surfaces influenced by compound layers and the diffusion nitriding zone [16,18,19] as well as the presence of iron borides and the formation of a solid solution of boron in iron [23][24][25][26]. In comparison, the surface treated with duplex gas-nitriding and pack boriding displayed the highest wear resistance due to the combined effect of enhanced mechanical properties, including increased hardness and elastic modulus.…”

“…The XRD analysis of DIN 16MnCr5 steel with thermal treatment of quenching and tempering at 870 °C for 15 min, diffusion treatments of gas-nitriding at 560 °C for 6 h, pack For nitriding and boriding patterns, the microstrain affects the width of the reflections but not their position in the diffractogram, as reported by Boca et al [30]. [23][24][25][26][27]. Finally, the diffraction patterns for duplex gas-nitriding and pack boriding were ε-Fe3N, γ'-Fe4N, FeB, Fe2B, MnB, and Cr2B.…”

“…The formation of a boriding layer with chemical composition elemental mapping of boriding layers with a thickness of ~70 µm and ~80 µm on DIN 16MnCr5 is shown in Figure 2b. It has been reported [23,26] that the boriding layer's FeB and Fe 2 B phases increase the hardness and improve the wear resistance. The surface's cross-section analysis by SEM and the elemental composition EDS mapping of layers formed by gas-nitriding and pack boriding layers with a thickness of ~80 µm and ~100 µm are shown in Figure 2c.…”

“…boron in iron [23][24][25][26]. In comparison, the surface treated with duplex gas-nitriding and pack boriding displayed the highest wear resistance due to the combined effect of enhanced mechanical properties, including increased hardness and elastic modulus.…”

“…Kováč et al [25] investigated the influence of the boronizing process on the wear properties of 16MnCr5 steels, observing increases in hardness and wear resistance. Moreover, Drajewicz et al [26] analyzed the microstructure within the diffusion pack boriding process, showing the potential to improve mechanical properties. The impact of temperature and duration of boriding on the nanohardness and modulus of elasticity of DIN 16MnCr5 steel was studied by Calik et al [27].…”