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Carbon-boron steels are widely used as components in ground engaging tools and agriculture components, being subject to different forms of tribological wear. The use of treatments to produce hard layers and wear resistance can significantly increase the time to failure and reduce operating costs. In this work, boriding and thermo-reactive deposition (TRD) treatments for the production of boride and carbide layers were performed on the substrates of AISI 15B30 steel to improve tribological characteristics of the surface. The compound phases present in the layers and properties such as hardness, adhesive wear resistance, and layer adhesion were characterized by optical microscope, x-ray diffraction, Knoop microhardness, microadhesive wear test and Rockwell C indentation adhesion according to VDI 3198. The results showed layers with high hardness (1400-2500 HK), greater microadhesive wear resistance (between approximately 10 and 14 times higher than the substrate) and excellent delamination resistance. [ABSTRACT FROM AUTHOR]

Abstract The modified layers were prepared on the Ti-6Al-4V surface using plasma-pulsed detonation (PPD) treatment. The effects of number of pulses on the microstructure, phase composition, microhardness and wear resistance of the modified layers were studied, and the strengthening mechanism of the modified layers was discussed. The results show that the modified layers are composed of TiN, Ti x O y and Ti phases. The grains of the modified layers are refined to nanoscale (≤100 nm) or near-nanometer (100–300 nm). The increase of the Ti-6Al-4V surface microhardness is mainly attributed to the second phase strengthening and the fine grain strengthening. The average microhardness of the modified layers increases with increasing the number of pulses, and the maximum microhardness value of the all modified layers is at 10 μm near the surface. In addition, the maximum microhardness value of the all modified layers can be up to 561 ± 9 HK 0.01 , which is about 69% higher than that of the substrate. After PPD treatment, the wear mechanism changes from typical abrasive wear and adhesive wear to three-body abrasive wear. Compared with the substrate, the wear volume decreases by about 70%, 79% and 87%, when number of pulses are 1, 2 and 3, respectively, indicating that the wear resistance of Ti-6Al-4V can be greatly improved after PPD treatment. Highlights • Plasma-pulsed detonation is used to improve wear resistance of Ti-6Al-4V. • The modified layers are composed of TiN, TixOy and Ti phases. • The second phase strengthening and the fine grain strengthening are the main mechanism. • The wear mechanism changes from abrasive wear and adhesive wear to three-body abrasive wear. [ABSTRACT FROM AUTHOR]

The production of vanadium and niobium carbides (VC and NbC) layers on AISI 8620, 8640, and 52100 steels may increase hardness and wear resistance of substrates. Thermochemical treatments were performed at 1000 °C for 2 and 4 h. The characterization of the treated samples was carried out by means of Knoop microhardness tests, "calotest" type microadhesive wear test, layer adhesion test according to VDI 3198 standard, and X-ray diffraction. Compact and uniform layers of VC and NbC were obtained in all treatments, with hardness up to 2500 HK and microadhesive wear resistance far superior to that of the substrates, indicating the great efficiency of these treatments for tribological applications. [ABSTRACT FROM AUTHOR]