Study On The Process And Properties Of Titanium Alloy After Surface Strengthen

Titanium alloys are widely used in the fields of aerospace etc due to its excellent properties including corrosion resistance and specific strength. But their application area is limited due to its bad wear resistence. In this thesis,A new process was explored to TC4, which was treated with carburizing and multi-component thermochemical treatment, to improve the performance of TC4alloy’s wear resistance.Samples were treated by two different processes.One was carburizing treatment,and the other was carburizing+multi-component thermochemical treatment. They were analyzed by metallographic microstructure analysis and XRD phase analysis. And severed properties were tested including microhardness, wear resistance, electrochemical polarization curve and tensile property.The metallurgical and XRD results showed that the surface layer of the sample through carburizing was mainly constituted with AlTi3C and Ti6O, and the layer’s depth reached45μm. The surface layer of the sample treated by carburizing+multi-component thermochemical treatment was mainly constituted with AlTi3C、AlTi3N and TiO2, and the layer’s depth reached65μm. The curve of microhardness results showed that highest hardness value in the layer after the carburizing reaches1400HV0.025, and the other reaches1050HV0.025., but the deeper the layer was. And the trend of the curve was more gradual. The friction wear testing showed that the friction coefficient of raw materials was0.4under the load of1N with SiC,3.3times higher than the samples treated by the two processes approximately. The untreated sample’s abrasion loss was21.5and113times higher than the samples carburized and carburizing+multi-component thermochemical treatment respectively.The analyse of electrochemical polarization curve showed that the treated samples had a higher corrosion potential so that the corrosion inclination was lower. But the corrosion current was higer indicated their corrosion speed was faster. The stress-strain curve and percentage of elongation indicated the samples’tensile strength was kept by both processes, but the plasticity declined a little, whereas the strain hardening was improved.The experiments and analyses showed the process of carburizing+multi-component thermochemical treatment improved TC4titanium alloy’s wear resistence. Besides, its corrosion resistence and strength were kept simultaneously.