The Effect of Thermal Inputs on Microstructure and Corrosion Resistance of WC Particle-Reinforced High Chromium Wear-Res

    
    Wear-resistant and corrosion-resistant high chromium steels have been extensively studied due to their potential application in severe environments. Their properties depend on the microstructural evolution and the changes in the microstructure that these steels undergo due to thermal inputs. One particular type of high chromium wear-resistant steel, WC particle-reinforced steel, was developed to have superior wear and corrosion-resistant properties. This type of steel is composed of a matrix of ferrite, chromium-rich veins, and small WC particles located at hardening particles of the matrix.
    
    The main objective of this study was to evaluate the effect of various thermal inputs on the microstructure and corrosion resistance of WC particle-reinforced high chromium wear-resistant steel. To do so, the precipitation sequence, microstructure evolution, and corrosion rate of the steel were evaluated.
    
    For the precipitation experiments, two different annealing treatments were used. The first one consisted of an oxide dispersion hardening process, which involved a cooling from 900°C (1652°F) to 700°C (1292° F ) and then heating to 700°C (1292° F ) again. The second one was a different thermal cycle, consisting of a cooling from 950°C (1742° F ) to 550°C (1022° F ).
    
    Results obtained during the thermal cycle showed that the morphological effects of the WC particles were maintained during the entire thermal cycle. However, a considerable evolution in the microstructure was observed, mainly due to the precipitation of chromium-rich phases. In particular, the precipitation of M3C carbides was observed to increase considerably after the two annealing treatments. As a consequence, the hardness values increased from 500 VHN to 750 VHN.
    
    The corrosion resistance of the steel was evaluated through the potentiodynamic polarization technique. This technique tested the materials for both corrosion potential and corrosion rate. The steel showed an excellent resistance to corrosion with a corrosion rate under 0.3 mm/year in solutions with pH ranging from 3 to 8.
    
    WC particle-reinforced high chromium wear-resistant steels are materials with great potential for applications in harsh environments. The results of this study show that thermal inputs play a critical role in the microstructural evolution and corrosion resistance of these steels. The steel showed excellent hardness, good microstructural stability, and excellent corrosion resistance. These findings can be used to design better thermal cycle treatments and improve the wear-resistance and corrosion-resistance properties of WC particle-reinforced high chromium wear-resistant steels.

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