High-strength high elasticity Cu-Ti alloy and its preparing process

[0023] The technical scheme of the invention is to use inert gas protection for melting and casting to avoid the effect of alloy elements on oxygen and nitrogen in the air; gas protection is provided in the melting and pouring process to realize the continuous production of Cu-Ti alloy. In the rolling process, the final rolling temperature of hot rolling and the intermediate annealing temperature in the cold rolling process are slightly higher than the solid solution line of the alloy, which can effectively prevent the alloy from forming lamellar structure in this process. The particle size is controlled at 2-10 μm. Through a suitable aging process, the diameter of the Cu-Ti intermetallic compound phase on the section perpendicular to the rolling direction is controlled between 0.02 and 0.2 μm. By adding an appropriate amount of the third element group, the occurrence of overaging can be delayed, the occurrence of cellular reactions can be suppressed, and the electrical conductivity of the alloy can be improved without reducing the strength of the alloy.

[0024] 1) Non-vacuum melting

[0025] Since the Cu-Ti alloy contains 3.0-4.0wt% Ti, when titanium is above 650°C, oxygen will diffuse into titanium to form a hard oxide layer; in addition, at above 700°C, nitrogen and titanium will react violently to form TiN. If it is smelted in the atmosphere, problems such as inhalation, oxygen absorption, and non-metallic inclusions will occur; similar problems are likely to occur in the open casting process, which affects the performance of the material. The invention adopts the submerged Cu-Ti alloy horizontal continuous casting technology. On the basis of the traditional horizontal continuous casting technology, the submerged copper replenishing process is used to completely seal the launder and the furnace, and inert gas is filled to ensure the melt and air Complete isolation to avoid defects such as inhalation and slag inclusion in the melt during smelting, laundering and pouring; during the production process, the material can be fed at any time through the feeding hole to adjust the alloy composition.

[0026] 2) Solution treatment during rolling

[0027] The Cu-Ti alloy forms a supersaturated solid solution through solution treatment. When it is aged at low temperature in this state, a metastable amplitude modulation structure will be formed. During a certain period of this process, the alloy will be significantly hardened, and over-aging will occur when the aging continues. After aging, stable TiCu is finally precipitated 3 phase, which softens the alloy. On the other hand, under the condition of insufficient solid solution, the titanium that is not completely solid solution will be replaced by TiCu 3 The state remains in the parent phase. In order to maximize the hardening under aging treatment, it is necessary to make TiCu in the solution treatment in the previous process. 3 The phase disappears completely, so that the titanium is completely dissolved in the parent phase. Therefore, it is necessary to heat to a temperature at which the solid solution temperature of titanium exceeds the content of titanium. In addition, the Cu-Ti alloy can improve its yield strength by fine grains in the annealing process, and the grain size on the cross section perpendicular to the rolling direction is between 2 and 10 μm; If it is less than 2 μm, the incompletely recrystallized part may remain, which will deteriorate the workability of the alloy. In the process of producing Cu-Ti alloys, the final recrystallization annealing process is equivalent to solution treatment. In the solution treatment, the grains are miniaturized and the yield strength is improved. In copper containing about 3wt% of titanium, the temperature is 750°C. Perform solution treatment or recrystallization annealing treatment between ~850°C.

[0028] 3) Aging treatment

[0029] The aging temperature should be selected at 350℃~450℃. Below 350°C, the Cu-Ti intermetallic compound phase is not sufficiently precipitated, and high strength and electrical conductivity cannot be obtained; if it is higher than 450°C, the Cu-Ti intermetallic compound phase is prone to coarsening and over-aging, resulting in Alloy strength decreases. The aging time is 5 to 20 hours. In addition, in the aging cooling process, in order to induce sufficient precipitation of the Cu-Ti intermetallic compound phase, the cooling rate from the aging temperature to 200 °C should not be higher than 50 °C/hour.

[0030] 4) Addition of the third element group

[0031] In order to delay the grain growth during the recrystallization annealing process, the TiCu 3 The precipitation of the phase, adding an appropriate amount of the third element group to form the second phase particles, the particles have thermal stability, can be formed during the solution treatment or the annealing process before the solution treatment, in the process of cold rolling and aging. , its shape hardly changes. The third element group is one or more of Cr, Co, V, Zr, B, Ni, and P, and the content is 0.01 to 0.5 wt %. The addition of these elements does not affect the formation of the AM structure, and the formed second phase particles are not for the purpose of precipitation hardening, but for the purpose of inhibiting the growth and over-aging of grains.

[0032] 【Example】

[0033] Using industrial electrolytic copper, sponge titanium and other trace alloy elements as raw materials, it is smelted in a gas-protected non-vacuum intermediate frequency induction furnace using graphite crucibles.

[0034] The 20 kg ingot was kept at 850°C for 24 hours, and the alloy composition was shown in Table 1 by ICP analysis. Then, the ingot was hot-rolled at 850°C, and solution treatment was performed at 860°C for 1 h after the hot-rolling. Some samples were taken out from the solid solution and annealed at different temperatures and at different times to observe the TiCu 3 The precipitation law of the phase, the TTT curve is shown in Figure 1.