Forging method for improving anisotropy and strength-toughness match of ultra-high strength and toughness beta titanium alloy

Abstract

The application belongs to the field of novel beta titanium alloy hot working, and particularly relates to a forging method for improving anisotropy and strength-toughness matching of super-high strength and toughness beta titanium alloy. The method comprises the following steps: homogenizing a rod, wherein the heating temperature is (Tbeta+30)~(Tbeta+100) DEG C, and high-temperature homogenization treatment is performed for 15-30 hours; high-temperature reversing upsetting and drawing forging, the heating temperature of each fire is reduced by 20-50 DEG C in turn, and the range of the heating temperature is (Tbeta+30)~(Tbeta+100) DEG C; blank forging to obtain a blank; and isothermal forging on the blank to obtain a forged piece. The beta titanium alloy forging process specification is formulated, the problem of anisotropy of TB17 titanium alloy is greatly improved, and the strength and plasticity and toughness are well matched.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new type of beta titanium alloy hot working, and particularly relates to a forging method for improving anisotropy and strength-toughness matching of super high strength and toughness beta titanium alloy. BACKGROUND

[0002] Metastable beta titanium alloy has high specific strength, deep quenching property, good corrosion resistance, excellent cold and hot forming property, and excellent strength-plasticity-toughness matching obtained through heat treatment strengthening, and is an ideal structural titanium alloy material. In recent years, metastable beta titanium alloy has been widely applied to important fields such as military and aerospace at home and abroad.

[0003] TB17 titanium alloy is a new type of metastable beta titanium alloy independently researched and developed by China, and has independent intellectual property rights. The strength of the alloy after heat treatment can reach more than 1260 MPa, and the alloy has good strength-plasticity-toughness matching, and is a super high strength and toughness titanium alloy with good development prospect for aviation structure. However, in actual production, the TB17 titanium alloy frequently has problems of strong mechanical property anisotropy and poor strength-toughness matching, and cannot meet the needs of aircraft manufacturing for titanium alloy forgings or parts, so it is an important factor to improve the anisotropy and strength-toughness matching of super high strength and toughness beta titanium alloy to reasonably formulate the main process and hot working parameters. SUMMARY

[0004] The technical problem to be solved by the application is to provide a forging method for improving anisotropy and strength-toughness matching of super high strength and toughness beta titanium alloy, and the problems of strong mechanical property anisotropy and poor strength-toughness matching of TB17 titanium alloy are solved through the modes of homogenization treatment, high-temperature reversing upsetting and drawing forging, blank forging and isothermal forging.

[0005] The technical scheme of the application is as follows:

[0006] A forging method for improving anisotropy and strength-toughness matching of super high strength and toughness beta titanium alloy, comprising the following steps:

[0007] Homogenization treatment of the rod material, wherein the heating temperature is (Tbeta+30)~(Tbeta+100) DEG C, and high-temperature homogenization treatment is performed for 15~30h;

[0008] High-temperature reversing upsetting and drawing forging, and the heating temperature of each fire is reduced by 20~50 DEG C in turn, and the range of the heating temperature is (Tbeta+30)~(Tbeta+100) DEG C;

[0009] Blank forging to obtain a blank;

[0010] Isothermal forging is performed on the blank to obtain a forged piece.

[0011] The high-temperature reversing upsetting and drawing forging comprises:

[0012] First heating: heating according to the heating specification of (Tβ+30)~(Tβ+100)℃×(0.4~0.8)min / mm, upsetting and then reversing and elongating, upsetting deformation being controlled at 45%, chamfering to octagon;

[0013] Second heating: heating according to the heating specification of (Tβ+30)~(Tβ+80)℃×(0.4~0.8)min / mm, upsetting and then reversing and elongating, upsetting deformation being controlled at 40%, chamfering to octagon;

[0014] Third heating: heating according to the heating specification of (Tβ+30)~(Tβ+50)℃×(0.4~0.8)min / mm, upsetting and then elongating, upsetting deformation being controlled at 35%, chamfering to octagon.

[0015] Blanking forging, comprising:

[0016] If there is no hot material recycling problem, each heating is according to the heating specification of (Tβ+30)~(Tβ+50)℃×(0.4~0.8)min / mm; deformation in each heating is controlled at 35%, and elongating to the size of a blank;

[0017] If there is a hot material recycling problem, first heating is according to the heating specification of (Tβ+30)~(Tβ+50)℃×(0.4~0.8)min / mm; other heating is according to the heating specification of (Tβ+30)~(Tβ+50)℃×(0.2~0.4)min / mm, deformation in each heating is controlled at 35%, and elongating to the size of a blank.

[0018] The heating specification for isothermal forging is:

[0019] (Tβ+30)~(Tβ+50)℃×(0.4~0.8)min / mm is executed, upsetting along the thickness direction, deformation being controlled at about 30%, and the pressing speed being controlled at 0.1~5mm / s.

[0020] During homogenization treatment, the surface needs to be coated with an antioxidant coating.

[0021] All heating processes are through electric furnace heating.

[0022] Blank transfer time is less than or equal to 60s, the forging deformation process is less than or equal to 5min, and the final forging temperature is not less than 750℃ after the forging deformation is completed.

[0023] The forging mode is free forging.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] 1. The traditional forging blank is forged according to the heating coefficient of 0.4-0.8 after heat preservation. The present application is to pre-treat the forging blank by high-temperature and long-time homogenization treatment, so that the elements are fully diffused, the micro-area composition uniformity is improved, the internal structure of the forging is statically recrystallized and grows to be consistent, and the TB17 titanium alloy structure uniformity is improved.

[0026] 2. The forging blank obtained by the traditional process at low temperature ((Tβ-40)~(Tβ+30)℃) has large difference in longitudinal and transverse (chord) mechanical properties, and has the problems of plasticity (transverse) not meeting the standard value, low fracture toughness value, and poor strength-toughness matching. The present application is to increase one heat isothermal forging on the basis of high-temperature reversing upsetting and drawing forging. The stress field and temperature field of the forging tend to be uniform during isothermal forging, the internal structure of the forging is fully dynamically recrystallized and formed into a net basket structure, the forging structure uniformity is ensured, the anisotropy of the mechanical properties of the forging is improved, and the forging has good strength-plasticity-toughness matching.

[0027] 3. The process of the present application is simple and feasible, and has strong operability, and is particularly suitable for improving the anisotropy and strength-toughness matching of the super-high strength and toughness β-type titanium alloy forging to meet the demand of aircraft manufacturing for titanium alloy forgings or parts. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The microstructure diagram of the forging blank in the embodiment.

[0029] Figure 2 The microstructure diagram of the final forging in the embodiment. DETAILED DESCRIPTION

[0030] The present application provides a forging method for improving the anisotropy and strength-toughness matching of super-high strength and toughness β-type titanium alloy, which comprises:

[0031] Homogenization treatment

[0032] The heating temperature is performed at (Tβ+30)~(Tβ+100)℃ for 24h high-temperature homogenization treatment (the surface needs to be coated with an anti-oxidation coating).

[0033] High-temperature reversing upsetting and drawing forging

[0034] First heat: the heating specification is performed at (Tβ+30)~(Tβ+100)℃×(0.4-0.8)min / mm, one upsetting and one drawing (reversing), the upsetting deformation amount is controlled at 45%, and the chamfering is to eight sides;

[0035] Second heating: heating specification is (Tβ+30)~(Tβ+80)℃×(0.4~0.8)min / mm, one upsetting and one drawing (reversing), upsetting deformation is controlled in 40%, chamfering to eight sides;

[0036] Third heating: heating specification is (Tβ+30)~(Tβ+50)℃×(0.4~0.8)min / mm, one upsetting and one drawing, upsetting deformation is controlled in 35%, chamfering to eight sides.

[0037] Blanking forging

[0038] Heating specification is (Tβ+30)~(Tβ+50)℃×(0.4~0.8)min / mm (hot material reheat can not be low temperature stage insulation, high temperature insulation time is calculated according to (0.2~0.4)min / mm), deformation is controlled in 35% per heating, drawing to the size of the forging blank.

[0039] Isothermal forging

[0040] Heating specification is (Tβ+30)~(Tβ+50)℃×(0.4~0.8)min / mm, thickness direction upsetting, deformation is controlled in about 30%, the reduction rate is controlled in 5mm / s;

[0041] The embodiment of the application discloses a kind of forging methods for improving the anisotropy and tough matching of super high strength and toughness TB17 titanium alloy, mainly includes the following steps:

[0042] Step one: the surface of bar material is coated with antioxidant paint, heated to (Tβ+80)~(Tβ+100) ℃, and subjected to 24h high temperature homogenization treatment;The organization of bar material before homogenization treatment is as shown in Figure 1 , and the performance is as shown in Table 1.

[0043] Table 1

[0044]

[0045] Step two: the blank is heated to (Tβ+80)~(Tβ+100)℃×0.4min / mm, and is upset to ~∅260×189±5 reversing square and drawn to ∅190±5×~278, chamfered to nearly eight sides.

[0046] Step three: the blank is heated to (Tβ+50)~(Tβ+80)℃×0.4min / mm, and is upset to ~∅260×189±5 reversing square and drawn to ∅190±5×~278, chamfered to nearly eight sides.

[0047] Step four: heat the blank to (Tβ+30)~(Tβ+50)℃×0.4min / mm (hot material can not be recycled low temperature stage, high temperature holding time according to 0.4min / mm), 190±5×278 inverted edge to 145±5×474, inverted edge to near eight;

[0048] Step five: heat the blank to (Tβ+30)~(Tβ+50)℃×0.4min / mm (hot material can not be recycled low temperature stage, high temperature holding time according to 0.4min / mm), 145±5×474 inverted edge to 105±3×145±3×670;

[0049] Step six: heat the blank to (Tβ+30)~(Tβ+50)℃×0.4min / mm, put into isothermal flat die, isothermal forging along the blank thickness 145(ST) direction to size 100(ST), pressing speed 5mm / s;

[0050] Step seven: heat treatment of the forging blank obtained in step six, to obtain the final forging, the microstructure of the final forging is as shown in Figure 2 , and the mechanical properties are as shown in table 2.

[0051] Table 2

[0052]

[0053] Further, the high temperature upsetting and drawing forging and blank making forging deformation process is carried out on a 1600T or 2500T fast forging machine, and the isothermal forging deformation process is carried out on a 100MN or 200MN oil press.

Claims

1. A forging method for improving anisotropy and strength-ductility balance of an ultra-high strength and toughness β-type titanium alloy, characterized by, The method comprises the following steps: homogenizing the rod, wherein the heating temperature is (Tβ+30)~(Tβ+100) ℃, and the high-temperature homogenization treatment is performed for 15~30 h; high-temperature alternate upsetting and drawing forging, the heating temperature of each heating process is reduced by 20~50 ℃ in turn, the range of the heating temperature is (Tβ+30)~(Tβ+100) ℃, and the specific heating process is as follows: the first heating process is heating according to the heating specification of (Tβ+30)~(Tβ+100) ℃×(0.4~0.8) min / mm, then upsetting and drawing, the upsetting deformation is controlled to be 45%, and the edge is chamfered to an octagon; the second heating process is heating according to the heating specification of (Tβ+30)~(Tβ+80) ℃×(0.4~0.8) min / mm, then upsetting and drawing, the upsetting deformation is controlled to be 40%, and the edge is chamfered to an octagon; the third heating process is heating according to the heating specification of (Tβ+30)~(Tβ+50) ℃×(0.4~0.8) min / mm, then upsetting and drawing, the upsetting deformation is controlled to be 35%, and the edge is chamfered to an octagon; blank forging, and a blank is obtained, and the specific blank forging process is as follows: if there is no hot material re-melting problem, each heating process is heating according to the heating specification of (Tβ+30)~(Tβ+50) ℃×(0.4~0.8) min / mm; the deformation of each heating process is controlled to be 35%, and the blank is drawn to the size of a forging blank; if there is a hot material re-melting problem, the first heating process is heating according to the heating specification of (Tβ+30)~(Tβ+50) ℃×(0.4~0.8) min / mm; the other heating processes are heating according to the heating specification of (Tβ+30)~(Tβ+50) ℃×(0.2~0.4) min / mm, the deformation of each heating process is controlled to be 35%, and the blank is drawn to the size of a forging blank; isothermal forging is performed on the blank to obtain a forging piece, and the heating specification of the isothermal forging is as follows: (Tβ+30)~(Tβ+50) ℃×(0.4~0.8) min / mm is executed, upsetting is performed along the thickness direction, and the deformation is controlled to be about 30%, and the pressing speed is controlled to be 0.1~5 mm / s.

2. The method of claim 1, wherein, During the homogenization treatment, the surface needs to be coated with an antioxidant coating.

3. The method according to claim 1 or 2, characterized in that, All the heating processes are performed by using an electric furnace.

4. The method according to claim 1 or 2, characterized in that, All the blank transfer times are less than or equal to 60 s, the forging deformation process is less than or equal to 5 min, and the final forging temperature is not less than 750 ℃ after the completion of the forging deformation.

5. The method of claim 1, wherein, The forging mode is free forging.

Images