Non-consumable electrode arc additive manufacturing method for refining titanium alloy grains through double-wire synchronous feeding

Abstract

The invention discloses a non-consumable electrode electric arc additive manufacturing method for refining titanium alloy grains through double-wire synchronous feeding, which comprises the following steps of: 1, fully cleaning the surface of a titanium alloy substrate, clamping and fixing in a to-be-welded area, and adjusting the tip position of a tungsten electrode to the initial position of an additive; 2, the tip of the welding wire is adjusted to be under the tungsten electrode to make contact with the titanium alloy substrate; thirdly, welding shielding gas is introduced in advance, and after the electric arc is stable, layer-by-layer stacked additive manufacturing is conducted on the titanium alloy substrate through a double-wire synchronous feeding method; and fourthly, the titanium alloy component obtained after additive manufacturing is completed is cooled and then taken down from the clamp, and electric arc additive manufacturing is completed. According to the method, through synchronous feeding of the double wires, the stability of the welding process at the high wire feeding speed can be effectively controlled, the energy of a unit welding wire is reduced, flowing of a molten pool is promoted, and then grain size refinement and distribution uniformity of the titanium alloy additive manufacturing component are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy arc additive manufacturing, and relates to a titanium alloy additive manufacturing method, and specifically to a non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding double wires. Background Art

[0002] Titanium alloys have great application potential in the aerospace field because of their advantages such as high specific strength, corrosion resistance, high temperature resistance and good creep resistance. For example, structures such as aircraft engine casings, turbine blades, and compressor blades all use titanium alloys in large quantities to reduce weight and improve mechanical properties.

[0003] Additive manufacturing technology is a technology that produces three-dimensional structures by stacking materials layer by layer. Compared with traditional casting and forging technologies, additive manufacturing technology does not require complex molds, improves production efficiency and flexibility, reduces production costs, and has huge economic benefits.

[0004] In the additive manufacturing process of titanium alloys, it is easy to produce coarse columnar grains that grow continuously along the additive direction, resulting in uneven mechanical properties of additively manufactured components: the strength in the horizontal direction is better than that in the vertical direction. Therefore, how to control the uniformity of grain size and mechanical properties of additively manufactured titanium alloy components is an important issue in the field of additive manufacturing technology. Summary of the invention

[0005] In order to solve the technical problems of coarse grains and uneven mechanical properties of titanium alloy components in additive manufacturing, the present invention provides a non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires, which achieves grain size control and mechanical property improvement of titanium alloy additive manufactured components.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires, such as Figure 2 As shown, the following steps are included:

[0008] Step 1: fully clean the surface of the titanium alloy substrate, place it on the welding positioner and clamp it in the area to be welded, and adjust the position of the tungsten electrode tip to the starting position of the additive material, wherein: the thickness of the titanium alloy substrate is 5 to 100 mm; the tungsten electrode tip is 2 to 10 mm (preferably 3 to 5 mm) away from the substrate surface;

[0009] Step 2: Figure 3 As shown, adjust the double-wire synchronous feeding fixture so that the angle between the two welding wires is 30-60°, the angle between the welding wire and the titanium alloy substrate is 10-30°, and the tip of the welding wire is directly below the tungsten electrode and in contact with the titanium alloy substrate;

[0010] Step 3, introduce welding shielding gas into the gas shielding hood 1 to 10 seconds (preferably 5 to 10 seconds) in advance, then turn on the welding power supply, and after the arc is stable for 1 to 5 seconds (preferably 1 to 2 seconds), use a double-wire synchronous feeding method to perform layer-by-layer additive manufacturing on the titanium alloy substrate cleaned in step 1 until the size of the titanium alloy component meets the use requirements, wherein: the welding mode of the welding machine is DC tungsten inert gas arc welding, and the working current is 100 to 200A; the wire feeding speed of the wire feeder is 1000 to 3000 mm / min; the welding speed of the welding positioner is 120 to 200 mm / min;

[0011] Step 4: Cool the titanium alloy component after the additive manufacturing in step 3, and then remove it from the fixture to complete the additive manufacturing process, wherein: the cooling method is natural cooling in the air.

[0012] The manufacturing mechanism of the present invention is as follows:

[0013] Additive manufacturing uses an electric arc as a heat source, which mainly relies on the electric arc to melt the additive material and evenly spread it on the base material, and finally forms an additive manufacturing component by stacking layer by layer. In the additive manufacturing process, due to the large temperature difference between the electric arc and the base material, during the solidification process of the additive material, coarse grains tend to grow along the direction of the temperature difference, resulting in directional grain growth, thereby reducing the mechanical properties of the additive manufacturing component. Therefore, it is necessary to control the growth process of the grains during the additive process. In the present invention, in the additive manufacturing process of titanium alloy, under the condition that the total heat input remains unchanged, more welding wires to be melted are introduced into the melting area of ​​the substrate by a double-wire synchronous feeding method, which can reduce the line energy acting on the welding wire per unit time, and the excessive unmelted welding wire enters the molten pool, which can promote the flow and heat and mass transfer of the molten pool. At the same time, the welding wire that is not fully melted plays a role in promoting heterogeneous nucleation of grains during the solidification process, thereby destroying the growth trend of grains in the same direction. Therefore, by using the additive manufacturing method of the present invention, it is possible to ensure that the grain size of the additively manufactured component is small and uniform.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. Compared with the existing arc additive manufacturing method, the present invention can effectively control the stability of the welding process at a higher wire feeding speed through the synchronous feeding of double wires, reduce the unit welding wire energy, promote the flow of the molten pool, and thus achieve the grain size refinement and distribution uniformity of titanium alloy additive manufacturing components, strengthen titanium alloy additive components, and is of great significance to titanium alloy arc additive manufacturing.

[0016] 2. The coaxial ultrasonic equipment in the present invention has low cost, simple process method and is easy to implement, and is suitable for the arc additive manufacturing field of titanium alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of double-wire synchronous feeding titanium alloy arc additive manufacturing, 1-tungsten electrode, 2-first wire feeder, 3-first welding wire, 4-second wire feeder, 5-second welding wire, 6-welding power supply, 7-titanium alloy substrate, 8-welding positioner switch, 9-gas shielding hood;

[0018] Figure 2 Workflow diagram for arc additive manufacturing of titanium alloy with dual wire synchronous feeding;

[0019] Figure 3 It is a schematic diagram of double wire synchronous feeding;

[0020] Figure 4 This is a comparison diagram of the macroscopic grain morphology of titanium alloy additive components prepared by the method of the present invention and the conventional arc additive manufacturing method. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0022] Embodiment 1:

[0023] This embodiment provides a non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires, the method comprising the following steps:

[0024] Step 1: Thoroughly clean the surface of the titanium alloy substrate. Figure 1 As shown, the titanium alloy substrate is placed on a welding positioner and clamped in the area to be welded, and the position of the tungsten electrode tip is adjusted to the starting position of the additive material, wherein: the thickness of the titanium alloy substrate is 10 mm, and the tungsten electrode tip is 5 mm away from the surface of the titanium alloy substrate.

[0025] Step 2: Adjust the dual-wire synchronous feeding fixture so that the angle between the two welding wires is 45°, the angle between the welding wire and the titanium alloy substrate is 15°, and the tip of the welding wire is directly below the tungsten electrode and in contact with the titanium alloy substrate.

[0026] Step 3: 5s in advance, introduce welding shielding gas into the gas shielding hood, then turn on the welding power supply, wait for 1s for the arc to stabilize, turn on the two wire feeder switches and the welding positioner switch simultaneously, and use the double wire synchronous feeding method to perform layer-by-layer additive manufacturing on the titanium alloy substrate cleaned in step 2, and stop when the additive manufacturing sample reaches 100mm in height. Among them: the welding mode of the welding machine is DC tungsten inert gas arc welding, the working current is 120A; the wire feeding speed of the wire feeder is 2000mm / min; the welding speed of the welding positioner is 180mm / min.

[0027] Step 4: Cool the titanium alloy component after the additive manufacturing in step 3, and then remove it from the fixture to complete the arc additive manufacturing, wherein: the cooling method is natural cooling in the air.

[0028] Figure 4 This is a comparison chart of the macroscopic morphology of the samples added by the conventional single-wire titanium alloy additive method and the additive method of the present invention. Figure 4 It can be seen that the conventional single-filament additive sample (left picture) is a macroscopic coarse columnar grain that grows continuously from bottom to top, and the average grain size is 4.65mm 2 The sample (right picture) produced by the additive manufacturing method of the present invention is fine, uniform, equiaxed crystals and short columnar crystals, with an average grain size of 0.59 mm. 2 The method of the present invention significantly improves the problem of coarse grains in additively manufactured titanium alloy components, and is beneficial to improving the performance of titanium alloy additively manufactured components.

[0029] Embodiment 2:

[0030] This embodiment provides a non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires, the method comprising the following steps:

[0031] Step 1: Thoroughly clean the surface of the titanium alloy substrate. Figure 1 As shown, the titanium alloy substrate is placed on a welding positioner and clamped in the area to be welded, and the position of the tungsten electrode tip is adjusted to the starting position of the additive material, wherein: the thickness of the titanium alloy substrate is 50 mm, and the tungsten electrode tip is 3 mm away from the surface of the titanium alloy substrate.

[0032] Step 2: Adjust the dual-wire synchronous feeding fixture so that the angle between the two welding wires is 60°, the angle between the welding wire and the titanium alloy substrate is 20°, and the tip of the welding wire is directly below the tungsten electrode and in contact with the titanium alloy substrate.

[0033] Step 3: 8s in advance, introduce welding shielding gas into the gas shielding hood, then turn on the welding power supply, wait for 2s for the arc to stabilize, and then turn on the two wire feeder switches and the welding positioner switch simultaneously. Use the double wire synchronous feeding method to perform layer-by-layer additive manufacturing on the titanium alloy substrate cleaned in step 2, and stop when the additive manufacturing component reaches a height of 50mm. Among them: the welding mode of the welding machine is DC tungsten inert gas arc welding, the working current is 150A; the wire feeding speed of the wire feeder is 3000mm / min; the welding speed of the welding positioner is 150mm / min.

[0034] Step 4: Cool the titanium alloy component after the additive manufacturing in step 3, and then remove it from the fixture to complete the arc additive manufacturing, wherein: the cooling method is natural cooling in the air.

Claims

1. A non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires, characterized in that The method comprises the following steps: Step 1: Fully clean the surface of the titanium alloy substrate, place it on the welding positioner and clamp it in the area to be welded, and adjust the position of the tungsten electrode tip to the starting position of the additive; Step 2: Adjust the double-wire synchronous feeding fixture so that the angle between the two welding wires is 30-60°, the angle between the welding wire and the titanium alloy substrate is 10-30°, and the tip of the welding wire is directly below the tungsten electrode and in contact with the titanium alloy substrate; Step 3: 1 to 10 seconds in advance, the welding shielding gas is introduced into the gas shielding hood, and then the welding power source is turned on. After the arc is stable for 1 to 5 seconds, a double-wire synchronous feeding method is used to perform additive manufacturing layer by layer on the titanium alloy substrate cleaned in step 1, until the size of the titanium alloy component meets the use requirements; Step 4: Cool the titanium alloy component after the additive manufacturing in step 3, and then remove it from the fixture to complete the additive manufacturing process, wherein: the cooling method is natural cooling in the air.

2. The non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires according to claim 1, characterized in that In the step 1, the tip of the tungsten electrode is 2 to 10 mm away from the surface of the substrate.

3. The non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires according to claim 2, characterized in that The tip of the tungsten electrode is 3 to 5 mm away from the surface of the substrate.

4. The non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires according to claim 1, 2 or 3, characterized in that The thickness of the titanium alloy substrate is 5 to 100 mm.

5. The non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires according to claim 1, characterized in that In the step 3, the welding shielding gas is introduced 5 to 10 seconds in advance.

6. The non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires according to claim 1, characterized in that In the step 3, the arc stabilization time is 1 to 2 seconds.

7. The non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires according to claim 1, characterized in that In the step three, the welding mode of the welding machine is DC tungsten inert gas arc welding, and the working current is 100-200A; the wire feeding speed of the wire feeder is 1000-3000mm / min; and the welding speed of the welding positioner is 120-200mm / min.

8. The non-melting electrode arc additive manufacturing method for titanium alloy grain refinement by synchronously feeding two wires according to claim 1, characterized in that In the step 4, the cooling method is natural cooling in the air.

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