The reaction of titanium alloy materials such as titanium rods and titanium tubes in air is closely related to temperature.

Titanium alloys are widely used because of its series of excellent properties. However, titanium alloys have high friction coefficients, are very sensitive to adhesive wear and fretting wear, have poor wear resistance, are easy to ignite at high temperature and high speed friction, and have relatively poor resistance to high temperature oxidation. The shortcomings seriously affect the safety and reliability of its structure and greatly limit its application. Therefore, improving the surface properties of titanium alloys such as wear resistance, high temperature oxidation resistance and corrosion resistance is an urgent problem to be solved. In addition to improving the composition and preparation process of the alloy, surface modification of titanium alloy is currently the most effective method.

In recent years, electron beam surface treatment technology has developed rapidly. When the electron beam with high energy density acts on the surface of the material, the surface of the material has physical, chemical or mechanical properties that are difficult to achieve by conventional methods, and the wear resistance and corrosion resistance of the material surface are significantly improved. And high temperature oxidation resistance. A domestic engineering technology company used pulsed high-current low-energy electron beams for surface treatment of titanium alloys and achieved good results.

The material used in the experiment is TA15 titanium alloy (Ti-6.5Al-2Zr-1Mo-1V). After the surface of the sample is polished, the surface is modified with a high-current pulsed electron beam. The electron beam acceleration voltage is 27kV, the target distance is 80mm, and the pulse The number of times is 10, and the pulse interval is 45s.

The hardness test of the obtained sample shows that as the depth increases, the hardness value first decreases and then increases, and finally tends to a fixed value. This special oscillating curve distribution can be explained as: under the pulsed high-energy rapid irradiation, a heating shock wave will sprout in the energy absorbing layer of the material, and it will be reflected back when it encounters the interface. Multiple irradiations cause interference and superposition of stress waves with each other, presenting a complex stress distribution state, resulting in a special distribution of cross-section microhardness.

The wear volume of the sample after electron beam treatment is 3 times higher than that of the original sample, indicating that the wear resistance of TA15 titanium alloy after electron beam treatment is improved. The reasons may be the following three aspects:

(1) The high energy of the electron beam is instantly deposited in a small area of ​​the subsurface layer of the material, so that the material quickly rises to the phase transition temperature or the melting temperature, and then the substrate heat conduction to achieve ultra-high-speed cooling (about 109K/s) to make the surface of the material The quenching effect occurs, which plays a role of solid solution strengthening, so the wear resistance of the surface is improved;

(2) The electron beam rapid solidification process will refine the grains of the surface layer of the material, thereby improving the wear resistance of the material;

(3) When the electron beam pulse acts on the surface of the material, the temperature begins to rise rapidly, and the inwardly propagating compressive thermal stress wave is generated due to the restraint of the rapid outward thermal expansion of the material surface. The residual stress forms a compressive stress distribution, which is beneficial to improve wear resistance.

The corrosion performance test showed that the corrosion potential of the original sample increased from -258.3mV to -107.5mV after the electron beam surface treatment, and the polarization resistance increased from 0.796k/cm2 of the original sample to 2.424k/cm2. At the same time, the self-corrosion current was higher than that of the original sample. Significant decline. This shows that the corrosion resistance of the sample is significantly improved. The main reasons for the improvement of corrosion performance are:

(1) The high temperature caused by the strong current pulsed electron beam irradiation on the surface of the sample can vaporize or desolute the adsorbed or adhered impurities on the surface of the material, and play a cleaning role;

(2) The surface of the material melts quickly, and then solidifies at the same high speed. This process inhibits equilibrium crystallization, and can obtain a dense non-equilibrium structure with uniform composition, which also inhibits the occurrence of self-corrosion to a certain extent;

(3) The rapid cooling of the surface layer of the material refines the surface grains, which leads to a reduction in the area ratio of the cathode and anode and reduces the corrosion rate.
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