| Titanium alloy is widely used in aerospace,shipbuilding,marine engineering,chemical,metallurgical and defense industry because it is with low density,high specific strength,excellent high temperature,low temperature performance,wear resistance and other properties.TC4(Ti-6Al-4V)which is the earliest development,is the most widely used titanium alloy in the world.Its production accounts for about half of the world's total output of titanium semi-finished products,exceeding 80%in the aerospace industry.The main features of the TC4 titanium alloy are developed at overall performance,good process characteristics and excellent superplasticity.Hence,it is suitable for forming with a variety of pressure processing methods,and the use of various methods of welding.The alloy which is mainly used in the annealed state can also be used to strengthen the aging solution,but the quenching surface cannot exceed 25?30mm.Solid solution aging is not suitable for thick work piece because A1 and V alloy elements are costly,the wide application of TC4 is limited.At present,for different conditions of using and processing requirements,countries have emerged in a number of TC4 titanium alloy modification.Ti-Al-V-Fe-O alloy is a new type of double-phase titanium alloy that is developed by ATI Corporation in the United States.It not only has high strength,but also has excellent comprehensive performance such as wear resistance,corrosion resistance and ductility.Low cost,so in the aerospace,military and other high-tech fields have been widely used.The alloy is added with an inexpensive Fe element instead of part V as a ?-stabilizing element,and O element instead of part A1 is added as a a-stabilizing element to reduce the cost of the alloy.The addition of Fe and O reduces the-thermodynamic stability of the ?-phase to obtain more ?-phase,improving the plasticity and strength of the alloy.Currently,Ti-Al-V-Fe-O titanium alloy is also utilized for military and aerospace industry research and development in the foreign.The annealed tissue of the alloy was coaxial,the other enhanced heat treatment process,alloying elements to strengthen the mechanical properties Mechanism and organizational evolution are not disclosed.In this experiment,smelting was carried out using ISM smelting technology and rolling was carried out to obtain a 5 mm thick hot rolled sheet,and the solution was subjected to solid solution aging treatment.The effects of solution temperature and aging temperature on microstructure,morphology,mechanical properties and wear resistance were studied.The mechanism of the solution was analyzed in details.Based on this experiment,the conclusion was made:The alloy is composed of a and ? before and after heat treatment.During the solution treatment,the transformation of a-phase to ?-phase transformation structure occurs and microscopic morphology changes from equiaxed tissue to lamina propria.After aging treatment,?-transformed microstructures decompose to produce secondary a-phase and lamellar tissue disappears.Besides,micro-morphology changes from chaotic bimodal to equiaxed tissue.After annealing at 910 ?,the strength decreased and the elongation after breaking was improved.When the temperature reached 940 ? the strength increased and the elongation decreased.When the solution temperature exceeds the transformation point,the sample appeared"? brittle" phenomenon,the performance dropped sharply,the strength and elongation decreased at the same time.After the aging treatment,the strength and plasticity of the lamellar metastable ?-structure were enhanced by the decomposition of the microstructures and the precipitation of the secondary a-phase.With the aging temperature increasing,the secondary a-phase gradually grew and the diffusion strengthening effect gradually decreased,so the strength decreased and the elongation gradually increased.940 ? × 15min/AC + 500 ? × 6h/AC heat treatment after the plate strength and elongation reached 1260MPa,8.5%,with better overall performance.Compared with the hot-rolled state,the hardness and wear resistance of the solution after aging were improved.As the aging temperature increased,the hardness of the sample decreased and the wear resistance decreased. |
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