F. Souza Neto

Bio: F. Souza Neto is an academic researcher from Instituto Tecnológico de Aeronáutica. The author has contributed to research in topics: Heat-affected zone & Filler metal. The author has an hindex of 2, co-authored 2 publications receiving 17 citations.

Influence of microstructures and wear behaviors of the microalloyed coatings on TC11 alloy surface using laser cladding technique

Abstract: Microalloyed coatings were fabricated on a forged TC11 titanium alloy surface by adding different amount of ZrN powders using laser cladding technique. Microstructures of coatings and heat affect zone were systematically investigated with the study of microhardness as well as wear property. Results indicated that all coatings have very uniform equiaxial grains with very fine α + β two-phase microstructure (the thickness of α lamellar is 0.8 μm), and nearly no change of microstructure for coatings was observed with the increase contents of ZrN from 3 wt% to 12 wt%. The changes of microstructure from coating to substrate are: fine α + β two-phase structure, super fine α + β two-phase structure (α lamellar of 0.2 μm), αp + αs + β structure, and α + β (forged). By increasing the contents of Zr and N, the hardness of coatings increased accordingly with no suddenly change at the interfacial region. Due to the strong solid-solution strengthening, coatings maintain high hardness even coarsening their microstructures. The enhanced hardness of coatings largely improves the wear properties of alloys to only more than twice of the TC11 matrix when addition of 12 wt% ZrN.

Surface hardening of laser melting deposited 12CrNi2 alloy steel by enhanced plasma carburizing via hollow cathode discharge

Abstract: Plasma carburizing of 12CrNi2 alloy steel fabricated by laser melting deposition was carried out in a propane-containing atmosphere at temperature of 930 °C with and without hollow cathode discharge (HCD). The generation of the HCD in the carburizing process was achieved by adding an auxiliary cathode opposite the alloy steel sample. The carburized samples were characterized by analysis of microstructure, microhardness and wear performance. The assistance of HCD increased the carbon concentration in the carburized layer and the case depth without changing the carburizing atmosphere and discharge voltage, indicating the improvement of carburizing kinetics. This leads to an increased volume fraction of acicular martensite and an increased the microhardness of the carburized layer as well as the improvement of the wear resistance of alloy steel.