Gr.17 is an alloy composed of Gr.1 (first-grade industrial pure titanium) + 0.04%~0.08% Pd. It belongs to α-type titanium alloy. Since Ti-Pd alloy not only retains the excellent corrosion resistance of industrial pure titanium in oxidizing media, but also has significantly improved corrosion resistance in reducing media, it is particularly important to resist localization in high temperature (above boiling point) chlorides. Ability to corrode. In addition, Pd is a slow eutectoid β-stable element. Increasing its content can reduce the susceptibility to hydrogen embrittlement. Therefore, Gr.17 titanium-palladium alloy is widely used in petroleum, chemical industry, metallurgy and other fields due to its strong corrosion resistance, hydrogen absorption resistance and crevice corrosion resistance.
This article mainly introduces the impact of the impurity elements Fe and O content and their heat treatment process and microstructure on the mechanical properties of Gr.17 titanium palladium alloy. It explores the corresponding rules and optimizes the reasonable heat treatment system, Fe, O content and its microstructure. The structure shape significantly reduces the yield strength and meets the requirements of technical standard 200629. It provides a technological basis for mass production of this alloy plate.


Experimental Method
The materials used for the test were Gr.17 alloy ingots melted in the vacuum electric arc furnace of the casting plant. They were opened and forged into square slabs in the forging plant. After grinding, the slabs were hot-rolled twice on a 3300 mm four-roller reversible rolling mill until the thickness reached the desired thickness. It is 8.0 mm hot rolled plate. The phase transformation point of the alloy is 880°C.
(1) Conduct mechanical property testing on 8.0 mm plates with impurity element Fe and O contents of 0.02%, 0.05%; 0.03%, 0.06%; 0.04%, and 0.08% respectively.
(2) 8.0 mm plates with the same chemical composition and the same processing technology were annealed at 680°C, 710°C, 740°C, 770°C, and 790°C for 1 hour respectively, and the mechanical properties were tested after annealing.
(3) Conduct mechanical property testing on 8.0 mm plates with different grain equiaxed structures (same chemical composition, same processing technology, annealing at different temperatures).

As the Fe and O content increases, the strength gradually increases and the elongation gradually decreases. The impurity elements Fe and O can form interstitial solid solutions with titanium, causing severe lattice distortion, strongly hindering dislocation movement, increasing strength, reducing plasticity, and also affecting fatigue performance, creep resistance, thermal stability, and notch sensitivity. Very harmful. Therefore, the contents of impurity elements Fe and O should be strictly controlled. In this study, due to the harsh yield strength σ 0.2 index, in order to further reduce the yield strength of the plate to meet the requirements of the technical standard 200629, the Fe and O content of the ingot and the oxidation and oxygenation during processing should be strictly controlled. , annealed in the range of 680~740°C. As the temperature increases, the strength decreases slightly, but the change amplitude is small. Between 680 and 740°C, the elongation gradually increases, but when the temperature increases to 770°C, the elongation decreases. This is the result of grain growth and coarsening, and should be avoided. On this basis, the preferred heat treatment temperature is 680~740°C. Under the same holding time, as the annealing temperature increases, the equiaxed α structure grains gradually increase. When the temperature increases to above 770°C, the grains coarsen significantly and product performance deteriorates. The yield strength of the plate corresponding to the equiaxed structure d does not meet the standard. This is because the higher the annealing temperature, the greater the degree of recovery. As a result, the stored energy after deformation is reduced and the grains are coarsened. The isometric structure a bc has a good match of strength and plasticity. The reason is that the difference in strain degree inside the fine grains and near the grain boundaries is small, which causes small stress concentration and can withstand large deformation. And the finer the grains, the more tortuous the grain boundaries are, which is not conducive to the propagation of cracks. It can be concluded that a uniform and fine equiaxed α structure is beneficial to the reduction of the yield strength and the improvement of the plasticity of the sheet. Therefore, a reasonable thermal processing process should be formulated to make the sheet have a uniform and fine equiaxed structure. In order to obtain better comprehensive mechanical properties.

Conclusion
(1) The content of impurity elements Fe and O is the main influencing factor on the yield strength of Gr.17 titanium-palladium alloy plate. The Fe and O content of the ingot and the oxidation and oxygenation during the processing must be strictly controlled.
(2) The preferred heat treatment temperature is 680~740℃.
(3) Uniform and fine equiaxed α structure is beneficial to reducing the yield strength and improving plasticity of the plate. Through the above analysis of factors affecting the yield strength of Gr.17 titanium-palladium alloy plates, the relevant relationships and rules were obtained. Based on this, the parameters were optimized and the reasonable chemical composition, thermal processing technology and heat treatment system were determined to make the finished product The yield strength of the plate is significantly reduced and the plasticity is improved. The mechanical properties of the plate meet the standard requirements of technical standard 200629. It provides a technological basis for mass production of this alloy plate in the future.