CN103045978B - Preparation method of TCl8 titanium alloy plate - Google Patents

Abstract

The invention discloses a preparation method of a TC18 titanium alloy plate, comprising: (1) forging an ingot; (2) solution treatment; (3) hot rolling; (4) stress relief and α-phase quenching and tempering heat treatment; 5) surface treatment; (6) cold rolling; (7) aging heat treatment. Through the control of process conditions such as rolling and heat treatment, the present invention can obtain TC18 plates of various toughness levels to meet different performance requirements, among which the strength of high-strength level plates reaches above 1300MPa; the strength of low-strength and high-toughness level plates reaches above 1100MPa , while the fracture toughness remains above 60MPa·m ^1/2 .

Description

Preparation method of TC18 titanium alloy plate

technical field

The invention relates to a preparation method of a TC18 titanium alloy plate, in particular to a preparation technology of an ultra-high strength and toughness titanium alloy plate.

Background technique

TC18 titanium alloy is a high-strength and high-toughness near-β titanium alloy, which has the advantages of high strength (≥1100MPa), good fracture toughness (K _1C ≥50MPa·m ^1/2 ), and small difference between yield strength and tensile strength. Large load-bearing structural parts have been widely used in the aerospace field.

However, due to the high deformation resistance and high deformation difficulty of TC18 alloy, especially in the solid solution state, the cold rolling deformation is small (≤ 25%), so the traditional titanium and titanium alloy hot rolling-cold rolling-heat treatment-finished system is adopted. It is difficult to realize the processing of TC18 alloy sheet. The application of TC18 alloy is limited.

Contents of the invention

The purpose of the present invention is to provide a preparation method for preparing TC18 plate.

In order to achieve the above object, the technical solution adopted in the present invention comprises the following steps:

(1) Ingot reforging:

The TC18 alloy forging billet is re-forged, the re-forging temperature is 780-850°C, the thickness of the slab after re-forging is 40-60mm, the fire times are 3-25, and the α phase content is controlled at 35-50%;

(2) Solution treatment:

Solid solution temperature 750℃~850℃, holding time 1~3h;

(3) Hot rolling:

The hot rolling temperature is 650~850°C, the deformation of each pass is 10~20%, and the total deformation is greater than 50~80%, and then air-cooled to 0~50°C;

(4) Stress relief and α-phase quenching and tempering heat treatment:

The heat treatment temperature is 650~800°C, the holding time is 1~3h, and after the holding is completed, cool to 0~50°C;

(5) Surface treatment:

Steel balls, zirconia or alumina shot peening is used to remove the scale on the surface of the plate, and then pickling is carried out. The volume ratio of the pickling solution is HF:HNO ₃ :H ₂ O=6~8:10~12:80~85, The purity of HF and _HNO3 is industrial pure, and the pickling temperature is 55~65°C;

(6) Cold rolling:

The pass deformation is 3~8%, and the total deformation is 15~40%;

(7) Aging heat treatment:

The heat treatment temperature is 400~620°C, the time is 4~10h, and cooled to 0~50°C.

Compared with the prior art, the present invention has the advantages of:

①For the first time, the heat treatment is integrated into the whole hot rolling and cold rolling process, in which the spherical α phase with a size of 2μm~5μm and a content of 15%~20% is obtained through step (2) solution treatment, which is beneficial to hot rolling deformation; (4) Quenching and tempering treatment further forms a thick needle-like α phase with a content of about 10%, which is beneficial to cold rolling deformation; through step (7) aging treatment, an ultra-fine acicular α phase with a content of about 10% is further precipitated, which is conducive to improving the alloy ultimate strength. The corresponding adjustment of the phase structure at different process stages can ensure the smooth rolling and deformation of the TC18 thin plate, and is conducive to the matching adjustment of the mechanical properties of the alloy.

②The process is simple and easy, the processing window is wide, the process stability is strong, and it is easy to realize the regulation of the microstructure and the matching of the mechanical properties of the corresponding alloy.

③Through the control of process conditions such as rolling and heat treatment, TC18 plates of various toughness levels can be obtained to meet different performance requirements. Among them, the strength of high-strength level plates reaches more than 1300MPa; the strength of low-strength and high-toughness plates reaches more than 1100MPa, At the same time, the fracture toughness remains above 60MPa·m ^1/2 .

Detailed ways

The present invention will be further described below in conjunction with implementation examples.

Example 1

(1) Ingot reforging:

The TC18 billet with a cross-sectional size of 110mm×200mm was re-forged on a 3000T hydraulic fast forging machine, heated by a natural gas furnace, and the re-forging was completed in 12 fires: the first to sixth fires were carried out at 850°C, kept for 2 hours and then out of the furnace for forging, after 4 times Upsetting is completed after 4 times of elongation; the 7th to 12th fire is carried out at 800 ° C, and it is forged after holding for 2 hours. Size 20mm×300mm×450mm;

(2) Solution treatment:

Put the reforged slab into a natural gas heating furnace at a heating temperature of 840°C and keep it warm for 1h.

(3) Hot rolling:

Hot rolling is carried out on a hot rolling mill with a roll diameter of 550mm. The reduction in the first pass is 10%, and the reduction in the second pass is 15%. After 6 passes, the final rolling thickness is Approx. 4.5mm sheet.

(4) Stress relief and α-phase quenching and tempering heat treatment:

Put the hot-rolled sheet into a natural gas heating furnace at a heating temperature of 800°C, keep it warm for 1 hour, and then air-cool it to 30°C.

(5) Surface treatment:

Use 3~5mm alumina balls for shot peening to remove the scale on the surface of the board, and then pickle. The volume ratio formula is HF:HNO ₃ :H ₂ O=6:11:83, and the purity of HF and HNO ₃ is industrial pure. , pickling temperature is 55 ℃.

(6) Cold rolling:

The cold rolling is carried out on a multi-roll cold rolling mill with a specification of 420mm, and the pass reduction is 4%. After 4 passes of rolling, the plate is finally rolled into a plate with a thickness of about 2.8mm.

(7) Aging heat treatment:

The aging temperature is 620°C, the time is 4h, and cooled to 30°C.

The final mechanical properties and fracture toughness at room temperature are shown in Table 1.

Table 1 Mechanical properties of TC18 sheet at room temperature in Example 1

Example 2

(1) Ingot reforging:

The TC18 billet with a cross-sectional size of 110mm×200mm was re-forged on a 3000T hydraulic fast forging machine, and the re-forging was completed in 12 fires: the first to sixth fires were carried out at 840°C, kept for 2 hours and then out of the furnace for forging, after 4 times of upsetting 4 times Finished after elongation; the 7th to 12th fires are carried out at 800°C, heat for 2 hours and then out of the furnace for forging, after 4 times of upsetting and 4 times of elongation, it is completed, and then forged into a slab at the 12th fire, the size of the slab is 50mm×200mm ×300mm.

(2) Solution treatment:

Put the reforged slab into a natural gas heating furnace at a heating temperature of 800°C, and conduct subsequent hot rolling directly after holding for 2 hours.

(3) Hot rolling:

Hot rolling is carried out on a 550mm hot rolling mill. The reduction in the first pass is 10%, and the reduction in the second pass is 15%. After 12 passes, the final rolling thickness is about 10mm. of plates.

(4) Stress relief and α-phase quenching and tempering treatment:

Put the hot-rolled sheet into a natural gas heating furnace at a heating temperature of 720°C, keep it warm for 2 hours, and then air-cool it to 30°C.

(5) Surface treatment:

Use 3~5mm zirconia balls for shot blasting to remove the scale on the surface of the plate, and then pickle. The volume ratio formula is HF:HNO ₃ :H ₂ O=6:12:82, and the purity of HF and HNO ₃ is industrial pure. , pickling temperature is 55 ℃.

(6) Cold rolling:

The cold rolling is carried out on a 420mm multi-roll cold rolling mill with a reduction of 2.5% per pass. After 6 passes of rolling, the plate is finally rolled into a plate with a thickness of about 6.2mm.

(7) Aging treatment:

The aging temperature is 550°C, the time is 6h, and cooled to 30°C.

The final room temperature mechanical properties and fracture toughness are shown in Table 2.

Mechanical properties of the TC18 sheet at room temperature in Table 2 Example 2

Example 3

(1) Ingot reforging:

The TC18 billet with a cross-sectional size of about 110mm×200mm is re-forged on a 3000T hydraulic fast forging machine, and the re-forging is completed in 12 fires: the first to sixth fires are carried out at 830°C, and the furnace is forged after 2 hours of heat preservation. After 4 times of upsetting 4 It is completed after the first drawing; the 7th to 12th fires are carried out at 810°C, and the furnace is forged after holding for 2 hours. After 4 times of upsetting and 4 times of drawing, it is completed, and it is changed into a slab at the 12th fire, and the size of the slab is about 8mm. ×200mm×300mm.

(2) Solution treatment:

Put the reforged slab into a natural gas heating furnace at a heating temperature of 750°C, and conduct subsequent hot rolling directly after holding for 3 hours.

(3) Hot rolling:

Hot rolling is carried out on a 550mm hot rolling mill. The reduction in the first pass is 10%, and the reduction in the second pass is 15%. After 8 passes, the final rolling thickness is about 2mm. of plates.

(4) Stress relief and α-phase quenching and tempering treatment:

Put the hot-rolled sheet into a natural gas heating furnace at a heating temperature of 650°C, keep it warm for 3 hours, and then air-cool it to 30°C.

(5) Surface treatment:

3~5mm steel balls are used for shot blasting to remove scale on the surface of the plate, and pickling is carried out. The volume ratio formula is HF:HNO ₃ :H ₂ O=6:10:84, and the purity of HF and HNO ₃ is industrial pure. The pickling temperature is 55°C.

(6) Cold rolling:

Cold rolling is carried out on a multi-roll cold rolling mill with a specification of 420mm, and the reduction in each pass is about 2.5%. After 10 passes of rolling, the plate is finally rolled into a plate with a thickness of about 1.2mm.

(7) Aging treatment:

The aging temperature is 450°C, the time is 10h, and cooled to 30°C.

The final mechanical properties and fracture toughness at room temperature are shown in Table 3.

Mechanical properties of TC18 sheet at room temperature in Table 3 Example 3

Claims (1)

1. a preparation method for TC18 titanium alloy plate, is characterized in that: comprise the following steps

(1) ingot blank changes forging:

TC18 alloy forging stock is changed to forging, change to forge and divide 12 fire to complete: the 1st to 6 fire carry out at 830～850 ℃, the forging of coming out of the stove after insulation 2h completes after 4 pullings of 4 jumping-ups; The 7th to 12 fire carry out at 780～810 ℃, and the forging of coming out of the stove after insulation 2h completes, and is forged into slab at the 12nd fire after 4 pullings of 4 jumping-ups, changes and forges rear slab thickness 40～60mm, and α phase content is controlled at 35～50%;

(2) solution treatment:

750 ℃ ~ 850 ℃ of solid solubility temperatures, soaking time 1 ~ 3h;

(3) hot rolling:

650 ~ 850 ℃ of hot-rolled temperatures, pass deformation 10 ~ 20%, total deformation is greater than 50 ~ 80%, then air cooling to 0～50 ℃;

(4) destressing and the mutually modified thermal treatment of α:

650 ~ 800 ℃ of thermal treatment temps, soaking time 1 ~ 3h, is cooled to 0～50 ℃ after being incubated;

(5) surface treatment:

After adopting steel ball or zirconium white or aluminum oxide shot peening to remove plate surface oxide skin, carry out pickling, pickle solution volume ratio formula is HF:HNO ₃: H ₂o=6 ~ 8:10 ~ 12:80 ~ 85, HF and HNO ₃purity be technical pure, pickling temperature is 55 ~ 65 ℃;

(6) cold rolling:

Pass deformation is 3 ~ 8%, and total deformation is 15 ~ 40%;

(7) timeliness thermal treatment:

400 ~ 620 ℃ of thermal treatment temps, time 4 ~ 10h, is cooled to 0～50 ℃.