Titanium alloy and dissimilar metal fusion welding material and preparation method and application thereof

Abstract

The invention is applicable to the technical field of welding, and provides a titanium alloy and dissimilar metal fusion welding material and a preparation method and application thereof, and the material comprises the following raw materials in percentage by weight: 68.5-71.5% of Pd, 28.0-31.5% of Ag, 0.1-0.5% of Zr and less than or equal to 0.5% of inevitable impurities. The high melting point of the alloy is guaranteed through the proportion of Pd and Ag, so that the high-temperature service requirement is met; silver preferentially forms a TiAg phase when reacting with titanium, and the TiAg phase is more plastic than a TiPd2 phase and can be used as a buffer layer to effectively inhibit or delay formation and overgrowth of the brittle TiPd2 phase, and the thickness of an interface brittle layer is controlled to be 1.5 microns or below; zr is added to preferentially react with interface oxygen in the welding process, the interface is purified, the wettability of the brazing filler metal is improved, meanwhile, the Zr element can be dissolved in palladium-silver alloy and an interface reaction layer in a solid mode, grains are refined, and the obdurability and creep resistance of the interface layer are further improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of welding, and particularly relates to a material for fusion welding of titanium alloy and dissimilar metals and a preparation method and application thereof. BACKGROUND

[0002] Titanium and its shape memory alloy are widely used in high-end watches, jewelry, medical devices and aerospace fields due to their excellent specific strength, biocompatibility and unique functional characteristics. However, the inherent high chemical activity, easy oxidation of titanium metal and poor compatibility with other metals in physical properties (such as thermal expansion coefficient, melting point) and metallurgy make it one of the most difficult materials to be welded with dissimilar metals in the world.

[0003] The existing technical bottlenecks include:

[0004] Brittle phase problem: titanium is extremely easy to react with common alloying elements such as Fe, Cu, Cr and Co at high temperature to generate hard and brittle intermetallic compound (IMC) phases such as TiFe2, TiCu2 and TiCr2, resulting in a sharp decrease in joint plasticity and brittle fracture under stress;

[0005] Oxidation contamination: titanium will absorb oxygen, nitrogen and hydrogen at more than 400℃, resulting in weld contamination, porosity and performance degradation, and the welding process must be carried out in a very high purity protective atmosphere or vacuum;

[0006] Thermal stress cracks: the thermal expansion coefficients of titanium and most metals differ significantly, resulting in huge residual stress during cooling and causing cracks;

[0007] Functional characteristic destruction: for titanium memory alloy, excessive heat input and incompatible interface reaction will change its phase transition temperature, destroying its shape memory effect and superelasticity.

[0008] In the prior art, only tantalum or niobium metal is known to be fusionable with titanium without repulsion, but the melting point of tantalum or niobium reaches 2500-3000℃, the material processing process is greatly limited, and the production cost is high, which cannot be mass-produced. Other metals are incompatible, brittle and cracked, and the structural bearing capacity and tensile strength drop sharply; at present, no material or technology can simultaneously solve the problems of interface brittleness, high tensile strength, high torsional strength, high temperature performance and memory function retention. SUMMARY

[0009] The purpose of the embodiments of the application is to provide a material for fusion welding of titanium alloy and dissimilar metals, which aims to solve the problems proposed in the background.

[0010] The material for fusion welding of titanium alloy and dissimilar metal according to the embodiment of the present application comprises the following raw materials in percentage by weight: Pd 68.5-71.5%, Ag 28.0-31.5%, Zr 0.1-0.5%, and unavoidable impurities ≤0.5%.

[0011] Another object of the embodiment of the present application is to provide a preparation method of the material for fusion welding of titanium alloy and dissimilar metal, comprising the following steps:

[0012] Smelting: high-purity palladium, silver and zirconium are smelted in a vacuum induction smelting furnace or an electric arc smelting furnace, the vacuum degree is not less than 5*10 -3 Pa, the smelting temperature is 1600-1700℃;

[0013] Plastic processing: the ingot is hot forged and hot rolled at 800-900℃, and then cold rolled to prepare a foil strip sheet;

[0014] Heat treatment: recrystallization annealing treatment is carried out at 750-850℃ in vacuum or a protective atmosphere, the time is 1-2 hours, and a uniform equiaxed crystal structure is obtained.

[0015] Another object of the embodiment of the present application is to provide the application of the material for fusion welding of titanium alloy and dissimilar metal in connecting titanium memory alloy and dissimilar metal.

[0016] The material for fusion welding of titanium alloy and dissimilar metal provided by the embodiment of the present application guarantees high melting point (~1450-1520℃) of the alloy by the proportioning of Pd 68.5-71.5% and Ag 28.0-31.5% to meet the high-temperature service requirement, meanwhile, the overall melting point of the material is effectively reduced (compared with pure palladium) by the addition of silver, the heat input required for welding is reduced, and the damage to the heat-affected zone of the titanium memory alloy is reduced; the introduction of silver preferentially forms TiAg phase when reacting with titanium, the phase is more plastic than TiPd2 phase, can act as a buffer layer, effectively inhibits or delays the formation and excessive growth of the more brittle TiPd2 phase, and controls the thickness of the interface brittle layer to be less than 1.5μm; the Zr added preferentially reacts with the interface oxygen during the welding process, purifies the interface, improves the wettability of the filler metal, meanwhile, the Zr element can be solid-solved in the palladium-silver alloy and the interface reaction layer, refines the grains, and further improves the strength and toughness and the creep resistance of the interface layer.

[0017] Compared with the prior art, the following significant advantages are obtained:

[0018] Fundamentally inhibit brittle phase: by the unique composition and proportioning design of palladium and silver and Zr micro-alloying, the thickness of the interface brittle layer (TiAg+trace TiPd2) is accurately controlled in the safe range of 0.5-2.0μm, and strong and tough metallurgical bonding is achieved.

[0019] Excellent joint performance: high joint strength, tensile strength ≥ 350 MPa, reaching more than 85% of the titanium memory alloy matrix, while having good fatigue performance and corrosion resistance;

[0020] Protection memory function: lower process temperature and precise pulsed laser heat input minimize the heat-affected zone of the titanium memory alloy, with a phase change temperature offset (ΔAs) of less than 5℃, perfectly preserving its shape memory effect and superelasticity;

[0021] Perfect color matching: the alloy is silver-white, highly consistent with platinum and K white gold color, achieving aesthetic invisibility (color difference ΔE < 1.5) in connection with K gold jewelry, which is not achievable with traditional yellow solder;

[0022] Strong process adaptability: the alloy can be used to connect titanium memory alloy with various dissimilar metals, such as 18K gold, 950 platinum, 316L stainless steel, silver-copper alloy, etc., covering multiple high-value-added fields such as watches, jewelry, glasses and medical devices. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Mechanical property test process and results diagram provided for embodiment 1 of the present application;

[0024] Figure 2 End-of-material real object diagram provided for embodiment 2 of the present application;

[0025] Figure 3 Flowchart of application provided for embodiment 2 of the present application;

[0026] Figure 4 Application results diagram provided for the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0028] The specific implementation of the present application is described in detail below in combination with specific embodiments.

[0029] Embodiment 1, a material for titanium alloy and dissimilar metal fusion welding, the preparation method comprising the following steps:

[0030] Melting: high-purity palladium (Pd, ≥99.95%), silver (Ag, ≥99.99%) and zirconium (Zr) are melted in a vacuum induction melting furnace or an electric arc melting furnace, with a vacuum degree not less than 5×10 -3Pa, smelting temperature 1600-1700℃, wherein Pd 70%, Ag 29.7%, Zr 0.3%, repeated smelting at least 3 times to ensure uniform composition;

[0031] Plastic processing: hot forging and hot rolling of the ingot at 800-900℃, followed by cold rolling to prepare foil strip sheet, finally to prepare foil strip sheet with thickness of 0.1-0.3mm;

[0032] Heat treatment: recrystallization annealing treatment at 750-850℃ under vacuum or protective atmosphere for 1-2 hours to obtain uniform equiaxed crystal structure.

[0033] Mechanical property test was performed on the material prepared in Example 1, as shown in Figure 1 the tensile force was 23.86kgf, greater than 350MPa, significantly higher than the strength of other metal joints <200MPa.

[0034] Example 2, a material for fusion welding of titanium alloy and dissimilar metal, the preparation method comprising the following steps:

[0035] Smelting: high-purity palladium (Pd), silver (Ag) and zirconium (Zr) were smelted in a vacuum induction melting furnace or an arc smelting furnace, the vacuum degree was not less than 5×10 -3 Pa, smelting temperature 1600-1700℃, wherein Pd 70%, Ag 29.7%, Zr 0.3%, repeated smelting at least 3 times to ensure uniform composition;

[0036] Plastic processing: hot forging and hot rolling of the ingot at 800-900℃, followed by cold rolling to prepare foil strip sheet, finally to prepare foil strip sheet with thickness of 0.1-0.3mm;

[0037] Heat treatment: recrystallization annealing treatment at 750-850℃ under vacuum or protective atmosphere for 1-2 hours to obtain uniform equiaxed crystal structure, as shown in Figure 2 .

[0038] The material prepared in Example 2 was applied to the connection of 1mm diameter titanium memory alloy and 14K / 18K gold, and the process included the following steps, as shown in Figure 3 .

[0039] Surface treatment: fine grinding and polishing of the surfaces to be connected of titanium memory alloy and dissimilar metal, and ultrasonic cleaning and pickling activation to remove oxide film and oil stains;

[0040] Assembly: the material for fusion welding of titanium alloy and dissimilar metal was used as an intermediate layer connecting sleeve between the surfaces to be connected;

[0041] Vacuum micro-beam pulsed laser fusion: in a vacuum chamber, vacuum degree ≤ 5*10 -3 Pa, completely eliminate gas pollution, pulse welding with a pulsed laser, laser power 30-50W, pulse width 1-5ms, frequency 50-200Hz, spot diameter 0.1-0.3mm, scanning speed 1-5mm / s;

[0042] Post-welding treatment: slowly cooled to below 300℃ in a vacuum environment, then filled with high-purity argon and cooled to room temperature to release residual stress;

[0043] The process successfully suppresses the formation of Ti-Fe brittle phase; the thickness of the interface reaction layer is 1.2μm; the mechanical bearing and sealing requirements are met, the joint tensile strength is 350 MPa (about 85% of the TiNi matrix), and the fatigue test is >100,000 cycles without damage (far exceeding the industry standard).

[0044] The material prepared in Example 2 is applied in jewelry welding, and the finished product is as shown in Figure 4 .

[0045] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A material for fusion welding of a titanium alloy to a dissimilar metal, characterized by, The material comprises the following raw materials in weight percentage: Pd 68.5-71.5%, Ag 28.0-31.5%, Zr 0.1-0.5%, unavoidable impurities ≤0.5%.

2. The titanium alloy fusion weld to dissimilar metal material of claim 1, wherein, The material comprises the following raw materials in weight percentage: Pd 70%, Ag 29.7%, Zr 0.3%.

3. The titanium alloy fusion weld to dissimilar metal of claim 1, wherein, The dissimilar metal is one of K gold, platinum, stainless steel, and silver copper alloy.

4. A method of producing a fusion welded material of a titanium alloy and a dissimilar metal according to any one of claims 1 to 3, characterized by, The method comprises the following steps: Smelting: high purity palladium, silver and zirconium are smelted in a vacuum induction smelting furnace or an electric arc smelting furnace, the vacuum degree is not less than 5x10 -3 Pa, smelting temperature 1600-1700°C; Plastic processing: hot forging and hot rolling of the ingot at 800-900℃, followed by cold rolling to prepare foil strip sheet; Heat treatment: recrystallization annealing treatment at 750-850℃ for 1-2 hours in vacuum or protective atmosphere to obtain uniform equiaxed crystal structure.

5. The method of producing a titanium alloy and dissimilar material fusion welded material according to claim 4, wherein The step of melting is repeated for more than 3 times.

6. The method of producing a titanium alloy and dissimilar material fusion welded material according to claim 4, wherein In the step of plastic processing, the thickness of the strip sheet is 0.1-0.3mm.

7. Use of the material of titanium alloy and dissimilar metal fusion welded as claimed in any one of claims 1-3 in connecting titanium memory alloy and dissimilar metal.

8. Use according to claim 7, characterized in that, The method comprises the following steps: Surface treatment: fine grinding and polishing of the surfaces to be connected of titanium memory alloy and dissimilar metal, and ultrasonic cleaning and pickling activation to remove oxide film and oil stains; Assembly: the material of titanium alloy and dissimilar metal fusion welded is used as an intermediate layer connecting sleeve between the surfaces to be connected; Vacuum micro-beam pulsed laser fusion: in the vacuum chamber, vacuum degree ≤ 5 × 10 -3 Pa, completely eliminate gas pollution, using pulsed laser for pulse welding, laser power 30-50W, pulse width 1-5ms, frequency 50-200Hz, spot diameter 0.1-0.3mm, scanning speed 1-5mm / s; Post-welding treatment: slow cooling to below 300℃ in vacuum environment, then filling with high-purity argon to cool to room temperature to release residual stress.

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