Novel titanium alloy partitioned beta heat treatment process

A titanium alloy and process technology, which is applied in the field of titanium alloy partition β heat treatment process, to achieve the effect of ensuring uniform structure, good comprehensive performance and low fatigue crack growth rate

Active Publication Date: 2014-02-26
AVIC BEIJING INST OF AERONAUTICAL MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to propose a titanium alloy zoned β heat treatment process that solves the microstructure uniformity and batch-to-batch stability of large complex variable-section titanium alloy forgings

Method used

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  • Novel titanium alloy partitioned beta heat treatment process
  • Novel titanium alloy partitioned beta heat treatment process
  • Novel titanium alloy partitioned beta heat treatment process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] TC4-DT titanium alloy is a large complex variable cross-section free forging after forging in the α + β zone (the maximum size of the outer shape is 2400 (L) mm × 590 mm (T) × 260 mm (ST), the maximum thickness is 260 mm, and the minimum thickness is 100 mm. The weight of the forging is up to 800kg). After adopting the above-mentioned divisional β heat treatment process, it is then kept at 730°C for 4 hours and air-cooled. The results of chemical anatomy analysis show that the microstructure uniformity of different parts of the forging is good ( figure 1 ), the uniformity of mechanical properties is good (Table 2 and Table 3), and the strength-plasticity-toughness matching is good.

[0027] Table 1 Tensile properties of different parts of free forgings

[0028]

[0029]

[0030] Table 2 Fracture toughness of different parts of free forgings

[0031]

Embodiment 2

[0033] TC4-DT titanium alloy is a large and complex variable cross-section die forging after forging in the α+β zone (the maximum size of the outer shape is 1720mm×1120mm×217mm, the maximum thickness is 217mm, the minimum thickness is 113mm, and the weight of a single piece is nearly 500Kg), using the above-mentioned partition β After the heat treatment process, the microstructure after being kept at 730°C for 4 hours and air-cooled is as follows: figure 2 As shown, it can be seen that the organization is a lamellar organization with good uniformity. The mechanical properties are shown in Table 3 and Table 4. Good strength-plasticity-toughness matching and low da / dN values ​​can be obtained after zoned β heat treatment.

[0034] Table 3 Tensile properties of different parts of die forgings

[0035]

[0036]

[0037] Table 4 Fracture toughness and crack growth rate of different parts of die forgings

[0038]

Embodiment 3

[0040] TC4-DT titanium alloy is a large and complex variable cross-section die forging after forging in the α+β zone (the maximum size of the outer profile is 1900mm×1375mm×160mm, the maximum thickness is 160mm, the minimum thickness is 130mm, and the weight of a single piece is nearly 500Kg), using the above-mentioned partition β After the heat treatment process, the microstructure after being kept at 730°C for 4 hours and air-cooled is as follows: image 3 As shown, it can be seen that the organization is a uniform lamellar organization. The mechanical properties are shown in Table 5 and Table 6. It can be seen from the table that the tensile properties and fracture toughness are higher than the standard requirements, and a good strength-plasticity-fracture toughness matching is obtained.

[0041] Table 5 Tensile properties of different parts of die forgings

[0042]

[0043] Table 6 Fracture toughness of die forgings

[0044]

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Abstract

The invention discloses an accuracy control-based novel titanium alloy partitioned beta heat treatment process. The process includes: first subjecting alpha+beta area forged alpha type and alpha-beta type titanium alloys to preheating at Tbeta-(20DEG C-40DEG C), calculating the heat preservation time according to t(min)=eta*delta max, with the delta max being the largest section thickness of a forged piece and the heating coefficient eta ranging from 0.5 to 0.8; then raising the temperature to (Tbeta-5DEG C)-(Tbeta+5DEG C) along with a furnace, and calculating the heat preservation time t(min) according to the above calculation formula, with the heating coefficient eta ranging from 0.2 to 0.6; and then raising the temperature to (Tbeta+5DEG C)-(Tbeta+30DEG C) along with the furnace again, and calculating the heat preservation time t(min) according to the above calculation formula, with the heating coefficient eta ranging from 0.2 to 0.5; and subjecting the forged piece discharged from the furnace to air cooling or cooling at certain cooling rate. The process is suitable for heat treatment of large, complex, variable section alpha type and alpha-beta type titanium alloy forged pieces, so that required high comprehensive performance lamellar structures with high ductility, high toughness and low fatigue crack propagation ability can be obtained, thus meeting the requirements of airplane and aero-engine manufacturing for large and complex variable section forged pieces or parts with uniform structure performance.

Description

technical field [0001] The invention relates to a precise control-based titanium alloy partition β heat treatment process. Background technique [0002] With the gradual adoption of advanced durability / damage tolerance design principles for large aircraft at home and abroad, titanium alloy forgings are required not only to have good strength and plasticity matching, but also to have high fracture toughness (K IC ) and low fatigue crack growth rate (da / dN). Compared with other types of titanium alloy microstructures (basket structure, two-state structure, and equiaxed structure), the lamellar structure has a certain width of bundled sheet-like distribution of the α phase, which makes the crack propagation form a tortuous path, so it can obtain a lot of High K IC value and lower da / dN. However, the disadvantage of the lamellar structure is that the grain boundaries of the β grains are continuous and straight α phases, which significantly reduces the plasticity of the alloy....

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22F1/18
Inventor 朱知寿王新南商国强费跃李军祝力伟
Owner AVIC BEIJING INST OF AERONAUTICAL MATERIALS
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