A defect control method for titanium alloy linear friction welding joint

Abstract

The present invention belongs to the technical field of linear friction welding, and in particular, relates to a method for controlling defects in linear friction welding joints of titanium alloys. According to the shape of the blade welding section, the reserved welding processing amount is expanded outward to form a preliminary welding surface contour line; the preliminary designed welding surface contour line is checked to see whether there is a part of the contour line within the concave range of the straight line connecting the two points; if not, the welding surface design is qualified and a process test is carried out; if so, it is necessary to connect the relevant contour line parts by straight lines, and perform curve fitting on the node parts at both ends to achieve a smooth transition, ensuring that between any two points on the edge of the welding surface, the welding surface contour line should protrude outside the straight line between the two points; after the contour line is corrected, a process test is carried out. The present invention ensures that the linear friction welding of the titanium alloy test piece will not produce unwelded defects by designing and controlling the shape of the welding surface of the titanium alloy test piece, thereby improving the welding quality of the product.

Description

Technical Field

[0001] The invention belongs to the technical field of linear friction welding, and in particular relates to a method for controlling defects of a titanium alloy linear friction welding joint. Background Art

[0002] Linear friction welding technology has become one of the mainstream manufacturing technologies for the fourth-generation fighter jets abroad due to its advantages of saving raw materials, shortening processing cycles, and good weld quality. Aircraft engine companies such as GE and PW in the United States, SNECMA in France, and RR in the United Kingdom have all adopted linear friction welding technology for the manufacture of integral blade disc parts.

[0003] Chinese patent publication number CN109175673A proposes a method for quality control of blade linear friction welding joints, which includes: intercepting a blade section at the height of the welding position; offsetting the two sides of the position where the thickness of the blade section is the largest; drawing a circle with the maximum distance between the two sides after the offset as the diameter, and the center of the circle is the midpoint of the maximum distance line segment between the two sides after the offset; moving the center of the circle along the center line of the blade section to form a contour trajectory; connecting the farthest points of all circles on both sides of the blade section in the contour trajectory, and the area enclosed by the two connected line segments and the circles at both ends of the blade section is the welded cross-sectional area.

[0004] like Figure 1 As shown in the figure, the linear friction welding welding surface of the titanium alloy integral blade is a plane cut at the position of the blade close to the disk body. This welding surface is related to the blade twist angle and is an irregular shape. When the welding surface design is unreasonable, it is easy to produce some areas of unwelded defects, resulting in unqualified welded joints. Summary of the invention

[0005] The purpose of the present invention is to provide a titanium alloy linear friction welding joint defect control method, by designing and controlling the shape of the welding surface of the titanium alloy test piece, thereby ensuring that the linear friction welding of the titanium alloy test piece will not produce unwelded defects and improving the product welding quality.

[0006] The technical solution of the present invention is:

[0007] A method for controlling defects of a titanium alloy linear friction welding joint is provided. Between any two points on the edge of the welding surface, the welding surface contour line should protrude outside the straight line between the two points.

[0008] The titanium alloy linear friction welding joint defect control method is to design the integral blade linear friction welding surface according to the blade cross-section shape, reserve processing allowance in the blade cross-section, and finally form the welding surface contour line.

[0009] The defect control method of the titanium alloy linear friction welding joint is to check the contour line. Between any two points on the edge of the welding surface, the welding surface contour line should protrude outside the straight line between the two points. If there is a point that is not outside the direct straight line connecting the contour line points, curve modification and fitting are performed to ensure that it protrudes outside the straight line connecting the two points.

[0010] The titanium alloy linear friction welding joint defect control method comprises the following steps:

[0011] (1) According to the shape of the blade welding section, the welding reserved processing amount is expanded outward to form a preliminary welding surface contour line;

[0012] (2) Check the preliminary design of the welding surface contour line to see if there is a part of the contour line that is concave within the straight line connecting the two points;

[0013] (3) If there is no part of the contour line that is within the concave range of the straight line connecting the two points, the welding surface design is qualified and the process test is carried out;

[0014] (4) If a part of the contour line is within the concave range of the straight line connecting the two points, it is necessary to connect the relevant contour line parts with straight lines and perform curve fitting on the node parts at both ends to achieve a smooth transition and ensure that the contour line of the welding surface should protrude outside the straight line between the two points between any two points on the edge of the welding surface;

[0015] (5) After the contour line is corrected, the process test is carried out.

[0016] The design idea of ​​the present invention is:

[0017] During the linear friction welding process, the welding temperature at different places on the welding surface is not exactly the same. The temperature is higher where the friction work is more, and the temperature is lower near the edge. If the welding temperature does not reach the welding temperature, metallurgical bonding will not be achieved in some areas, resulting in unwelded defects.

[0018] Increasing the welding energy input is a solution. The present invention starts from the design of the welding surface structure and tries to make the welding surface temperature uniform, thereby avoiding the occurrence of unwelded defects. The specific welding surface design principle method is: between any two points on the edge of the welding surface, the welding surface contour line should protrude outside the straight line between the two points. The present invention controls the shape of the welding surface of the titanium alloy test piece by design, thereby ensuring that the linear friction welding of the titanium alloy test piece will not produce unwelded defects and improving the welding quality of the product.

[0019] The beneficial effects brought by the technical solution of the present invention are:

[0020] 1. The present invention designs and controls the shape of the welding surface, eliminates the unwelded defects of linear friction welding, and reduces the number of welding process optimization tests.

[0021] 2. Linear friction welding technology is mainly used in the manufacture and repair of titanium alloy integral blades, and is also suitable for the welding of some structural parts. The world's advanced aircraft engine integral blades mostly use linear friction welding technology. Therefore, the titanium alloy linear friction welding joint defect control method can well ensure the production quality of aircraft engine parts and improve economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 .Schematic diagram of the linear friction welding surface of the integral blade.

[0023] Figure 2 . Schematic diagram of unreasonable design of linear friction welding surface of integral blisk.

[0024] Figure 3 .Schematic diagram of the modified design of the linear friction welding surface of the integral blade. DETAILED DESCRIPTION

[0025] When designing the linear friction welding surface of the integral blade, the blade section shape is designed, and the processing amount is reserved in the blade section to finally form the contour line of the welding surface. Check the contour line. Between any two points on the edge of the welding surface, the contour line of the welding surface should protrude outside the straight line between the two points. If there is a point that is not outside the direct straight line connecting the contour line points, perform curve modification fitting to ensure that it protrudes outside the straight line connecting the two points. Figure 2 As shown in the figure, if the contour line between points AB is designed to be within the straight line connecting the two points, it is not the optimal welding surface and needs to be corrected.

[0026] like Figure 1-Figure 3 As shown, the defect control method of titanium alloy linear friction welding joint of the present invention is as follows:

[0027] 1. First, according to the shape of the blade welding section, a certain amount of welding reserve processing is expanded outward to form a preliminary welding surface contour line. The reserve amount depends on the welding process. Generally, the reserve amount is 1 to 3 mm.

[0028] 2. Check the preliminary design welding surface contour line to see if there is any Figure 2 In the case shown, a portion of the contour line is concave within the range of the straight line connecting the two points.

[0029] 3. If it does not exist, the welding surface design is qualified and the process test can be carried out.

[0030] 4. If it exists Figure 2 In this case, it is necessary to connect the relevant contour lines with straight lines and perform curve fitting on the nodes at both ends to achieve a smooth transition. Figure 3 As shown, ensure that between any two points on the edge of the welding surface, the welding surface contour line should protrude outside the straight line between the two points.

[0031] 5. After the contour line is corrected, process tests can be carried out.

[0032] The implementation results show that the present invention controls the shape of the welding surface by design, eliminates the defect of linear friction welding, and reduces the number of welding process optimization tests. The welding surface design is more reasonable, which can reduce the welding heat input and improve the quality of the welding joint. According to the calculation of reducing 5 welding optimization tests for welding one part, one welding optimization test costs 10,000 yuan, and one welded part can save 10,000 yuan × 5 = 50,000 yuan.

Claims

1. A titanium alloy linear friction welding joint defect control method, characterized in that: Between any two points on the edge of the weld surface, the weld surface contour line should protrude outside the straight line between the two points; When designing the linear friction welding surface of the integral blade, the blade section shape is designed according to the blade section shape, and the processing amount is reserved in the blade section to finally form the welding surface contour line; Check the contour line. Between any two points on the edge of the welding surface, the contour line of the welding surface should protrude outside the straight line between the two points. If it is not outside the direct straight line connecting the contour points, perform curve modification and fitting to ensure that it protrudes outside the straight line connecting the two points. The titanium alloy linear friction welding joint defect control method comprises the following steps: (1) According to the shape of the blade welding section, the welding reserved processing amount is expanded outward to form a preliminary welding surface contour line; (2) Check the preliminary design of the welding surface contour line to see if there is a part of the contour line that is concave within the straight line connecting the two points; (3) If there is no part of the contour line that is within the concave range of the straight line connecting the two points, the welding surface design is qualified and the process test is carried out; (4) If a part of the contour line is within the concave range of the straight line connecting the two points, it is necessary to connect the relevant contour line parts with straight lines and perform curve fitting on the node parts at both ends to achieve a smooth transition and ensure that the contour line of the welding surface should protrude outside the straight line between the two points between any two points on the edge of the welding surface; (5) After the contour line is corrected, the process test is carried out.

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