Forming method for increasing effective size of square billet forge piece and improving deformation uniformity

Abstract

The invention belongs to the technical field of titanium alloy material preparation, and relates to a forming method for increasing the effective size of a square billet forge piece and improving deformation uniformity. According to the method, prefabrication forming is conducted through free forging above the phase transformation point, arc-shaped edges can be eliminated through multiple times of shape modification, lamellar structures uniform in thickness can also be formed through large deformation, and the lamellar structures have good fracture toughness. Longitudinal and transverse interchange of the cuboid blank can be achieved through reversing forging and drawing, the longitudinal and transverse total deformation is balanced, and the uniformity of longitudinal and transverse structures and performance is guaranteed. By pressing the arc-shaped grooves, arc-shaped edges can be prevented from being formed when the next heating number of forgings is formed, the flowability of blanks is improved, the effective size of the forgings is increased, and the yield is increased. By controlling the deformation of the two-phase region, the continuous crystal boundary alpha phase can be broken, the recrystallization degree can be controlled, the short rod-shaped alpha phase is reserved, and good matching of fracture toughness and strength is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy material preparation, and relates to a forming method for increasing the effective size of a square billet forging and improving deformation uniformity. Background Art

[0002] Forgings are in the forming process. As the height decreases, the metal continues to flow around. Due to the friction between the billet and the die, the corners of the billet will be concave, and the center of the edge will protrude, forming an arc edge. During free forging, the arc edge can be trimmed by repeated upsetting, but free forging deformation has the problem of uneven deformation temperature and deformation speed, resulting in the forging structure and performance not meeting the requirements. Flat die isothermal forging can solve the problem of uneven deformation temperature and deformation speed, but during the deformation process, the arc edge cannot be repeatedly trimmed, which reduces the effective size of the square billet forging and increases the feed weight. In order to meet the organizational performance requirements and increase the effective size of the forging, a forming method for increasing the effective size of the square billet and improving deformation uniformity is proposed. Summary of the invention

[0003] The object of the present invention is to provide a forming method for increasing the effective size of a square billet forging, which can improve the arc edge and the unevenness of the structure and performance formed by the uneven deformation during the forging process of the square billet forging.

[0004] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0005] A forming method for increasing the effective size of a square billet forging and improving deformation uniformity, comprising: the size of the square billet forging is: L / B ≥ 1.5, B / H ≥ 1.3, 50 mm ≤ H ≤ 150 mm, wherein L, B and H are the length, width and height dimensions of the forging respectively, and the forming of the square billet forging comprises the following steps:

[0006] Step 1: respectively design anvil surfaces with arcs, the arc radius of the arc anvil surface a is R1, the arc height is W1=4L(H1-H) / (L+B), the arc radius of the arc anvil surface b is R2, and the arc height is W2=4B(H1-H) / (L+B);

[0007] Step 2: Heat the bar in an electric heating furnace, open forge and repeatedly upset and trim it into a prefabricated square billet, and air cool it;

[0008] Step 3: Place the prefabricated billet obtained in step 1 at (T β -20)℃ heating, T β The phase transition point of the alloy is the square billet subjected to reversing upsetting in the longitudinal and transverse directions;

[0009] Step 4: Align the center of the arc anvil surface a with the center of the long side of the prefabricated square billet, press into an arc groove and then cool; align the center of the arc anvil surface b with the center of the short side of the prefabricated square billet, press into an arc groove and then cool to obtain a rectangular billet with arc grooves on four sides.

[0010] Step 5: The rectangular blank obtained in step 4 is heated below the phase transformation point and is pressed down in the height direction for isothermal forging.

[0011] The heating temperature in the electric heating furnace is T β +(10~15)℃.

[0012] The size characteristics of the prefabricated square billet are: L1 / B1=(0.9-1.1)L / B, H1=(1.3-1.55)H, L1, B1, H1 are the length, width and height dimensions of the prefabricated square billet respectively.

[0013] The number of reversing upsetting and drawing in step 3 is 1 to 3 times.

[0014] The reversing upsetting and drawing in step three is to upset and draw the long side of the rectangular blank into the short side, and upset and draw the short side into the long side, while the height direction remains unchanged.

[0015] The anvil arc radius R1 is (L1 / 2) 2 +(H1-H) 2 / 2(H1-H); the radius of the anvil arc R2 is (B1 / 2) 2 +(H1-H) 2 / 2(H1-H).

[0016] The heating temperature below the phase transition point in step 5 is (T β -20)℃.

[0017] The deformation amount of the isothermal forging in step 5 is between 30% and 55%.

[0018] Technical effects of the present invention: Free forging prefabrication above the phase transformation point can eliminate arc edges through multiple shaping, and large deformation can also form a lamellar structure with uniform thickness, and the lamellar structure has good fracture toughness. Reversing forging and drawing can realize the longitudinal and transverse interchange of the rectangular billet, balance the total longitudinal and transverse deformation, and ensure the uniformity of the longitudinal and transverse organization and performance. By pressing the arc-shaped groove, the formation of arc edges during the next forging can be avoided, the fluidity of the billet can be improved, the effective size of the forging can be increased, and the success rate can be improved. By controlling the deformation amount of the two-phase zone, the continuous grain boundary α phase can be broken, and the degree of recrystallization can be controlled, the short rod-shaped α phase can be retained, and a good match between fracture toughness and strength can be obtained. DETAILED DESCRIPTION

[0019] In order to more clearly understand the purpose, technical solutions and advantages of the present invention, the present invention is further described in detail below in conjunction with embodiments.

[0020] A forming method for increasing the effective size of a square billet forging and improving deformation uniformity, comprising:

[0021] The dimensions of the square billet forgings to be characterized are: L / B ≥ 1.5, B / H ≥ 1.3, 50mm ≤ H ≤ 150mm, where L, B and H are the length, width and height dimensions of the forgings respectively. The forming of the square billet forgings includes the following steps:

[0022] Step 1: Design anvil surfaces with arcs respectively, the arc radius of the arc anvil surface a is R1, the arc height W1=4L(H1-H) / (L+B), the arc radius of the arc anvil surface b is R2, the arc height is W2=4B(H1-H) / (L+B); the anvil surface arc radius R1 is (L1 / 2) 2 +(H1-H) 2 / 2(H1-H); the radius of the anvil arc R2 is (B1 / 2) 2 +(H1-H) 2 / 2(H1-H).

[0023] Step 2: Heat the rod in an electric heating furnace at a temperature of T β +(10~15)℃; free forging and repeatedly upsetting and drawing to form a prefabricated square billet, the size characteristics of the prefabricated square billet are: L1 / B1=(0.9~1.1)L / B, H1=(1.3~1.55)H, L1, B1, H1 are the length, width and height dimensions of the prefabricated square billet respectively; then air cooling;

[0024] Step 3: Place the prefabricated billet obtained in step 1 at (T β -20)℃ heating, T β The phase transition point of the alloy is reached, and the billet is subjected to longitudinal and transverse reversing upsetting and drawing, and the number of upsetting and drawing is 1 to 3 times; the reversing forging and drawing can realize the longitudinal and transverse interchange of the rectangular billet, balance the total longitudinal and transverse deformation, and ensure the uniformity of the longitudinal and transverse organization and performance. The reversing upsetting and drawing is to upset the long side of the rectangular billet into the short side, and upset the short side into the long side, and the height direction remains unchanged.

[0025] Step 4: Align the center of the arc anvil surface a with the center of the long side of the prefabricated square billet, press into an arc groove and then cool; align the center of the arc anvil surface b with the center of the short side of the prefabricated square billet, press into an arc groove and then cool to obtain a rectangular billet with arc grooves on four sides.

[0026] Step 5: Heat the cuboid blank obtained in step 4 below the phase transition point. The heating temperature below the phase transition point is (T β-20)℃; press down along the height direction to perform isothermal forging, and the deformation of the isothermal forging is between 30% and 55%.

[0027] Embodiment 1:

[0028] The method is used to form a square billet with dimensions of L=602 mm, B=340 mm, H=70 mm. The steps are as follows:

[0029] Step 1: Heat the Ф320mm bar in an electric heating furnace at a temperature of 815℃, and repeatedly forge and draw to form a prefabricated square billet. The size of the prefabricated square billet is L1 = 475mm.

[0030] B1=280mm, H1=107.7mm and air cooled after forging.

[0031] Step 2: Heat the prefabricated billet obtained in step 1 at 780℃, and perform reverse forging and drawing on the billet, upsetting and drawing the long side of the rectangular billet into the short side, and upsetting and drawing the short side into the long side, while the height direction remains unchanged. Reversing forging and drawing can realize the longitudinal and transverse interchange of the rectangular billet, balance the total longitudinal and transverse deformation, and ensure the uniformity of the longitudinal and transverse organization and performance.

[0032] Step 3: Design anvil surfaces with arcs respectively, the radius of arc anvil surface a is R1=766mm, the arc height is W1=96mm, the radius of arc anvil surface b is R2=278mm, the arc height is W2=54mm, align the center of arc anvil surface a with the center of the two long sides of the prefabricated square billet, press into an arc groove. Align the center of arc surface b with the center of the two short sides of the prefabricated square billet, press into an arc groove and then cool.

[0033] Step 4: Heat the rectangular blank obtained in step 3 to 780° C., press it down in the height direction for isothermal forging, and control the deformation of the two-phase region to 35%. The forming is completed.

[0034] Embodiment 2:

[0035] The method is used to form a square billet with dimensions of L = 700 mm, B = 420 mm, H = 100 mm. The steps are as follows:

[0036] Step 1: Heat the Ф320mm bar in an electric heating furnace at a temperature of 815℃, and repeatedly forge and draw to form a prefabricated square billet. The size of the prefabricated square billet is L1=550mm.

[0037] B1=320mm, H1=167mm and air cooled after forging.

[0038] Step 2: Heat the prefabricated billet obtained in step 1 at 780℃, and perform reverse forging and drawing on the billet, upsetting and drawing the long side of the rectangular billet into the short side, and upsetting and drawing the short side into the long side, while the height direction remains unchanged. Reversing forging and drawing can realize the longitudinal and transverse interchange of the rectangular billet, balance the total longitudinal and transverse deformation, and ensure the uniformity of the longitudinal and transverse organization and performance.

[0039] Step 3: Design anvil surfaces with arcs respectively, the radius of arc anvil surface a is R1=597mm, the arc height is W1=168mm, the radius of arc anvil surface b is R2=224mm, the arc height is W2=100mm, align the center of arc anvil surface a with the center of the two long sides of the prefabricated square billet, press into an arc groove. Align the center of arc surface b with the center of the two short sides of the prefabricated square billet, press into an arc groove and then cool.

[0040] Step 4: Heat the rectangular blank obtained in step 3 to 780° C., press it down in the height direction for isothermal forging, and control the deformation of the two-phase region to 40%. The forming is completed.

Claims

1. A forming method for increasing the effective size of a square billet forging and improving deformation uniformity, comprising: The dimensions of the square billet forgings to be characterized are: L / B ≥ 1.5, B / H ≥ 1.3, 50mm ≤ H ≤ 150mm, where L, B and H are the length, width and height dimensions of the forgings respectively. The forming of the square billet forgings includes the following steps: Step 1: respectively design anvil surfaces with arcs, the arc radius of the arc anvil surface a is R1, the arc height is W1=4L(H1-H) / (L+B), the arc radius of the arc anvil surface b is R2, and the arc height is W2=4B(H1-H) / (L+B); Step 2: Heat the bar in an electric heating furnace, open forge and repeatedly upset and trim it into a prefabricated square billet, and air cool it; Step 3: Place the prefabricated billet obtained in step 1 at (T β -20)℃ heating, T β The phase transition point of the alloy is the square billet subjected to reversing upsetting in the longitudinal and transverse directions; Step 4: Align the center of the arc anvil surface a with the center of the long side of the prefabricated square billet, press into an arc groove and then cool; align the center of the arc anvil surface b with the center of the short side of the prefabricated square billet, press into an arc groove and then cool to obtain a rectangular billet with arc grooves on four sides. Step 5: The rectangular blank obtained in step 4 is heated below the phase transformation point and is pressed down in the height direction for isothermal forging.

2. The method according to claim 1, characterized in that The heating temperature in the electric heating furnace is T β +(10~15)℃.

3. The method according to claim 1, characterized in that The dimensional characteristics of the prefabricated square billet are: L1 / B1=(0.9~1.1)L / B, H1=(1.3~1.55)H, L1, B1, H1 are the dimensions of the prefabricated square billet in length, width and height directions respectively.

4. The method according to claim 1, characterized in that The number of reversing upsetting and drawing in step 3 is 1 to 3 times.

5. The method according to claim 1, characterized in that The reversing upsetting and drawing described in step 3 is to upset and draw the long side of the rectangular blank into the short side, and upset and draw the short side into the long side, while the height direction remains unchanged.

6. The method according to claim 1, characterized in that The radius of the anvil arc R1 is (L1 / 2) 2 +(H1-H) 2 / 2(H1-H); the radius of the anvil arc R2 is (B1 / 2) 2 +(H1-H) 2 / 2(H1-H).

7. The method according to claim 1, characterized in that The heating temperature below the phase transition point in step 5 is (T β -20)℃.

8. The method according to claim 1, characterized in that The deformation amount of the isothermal forging in step 5 is between 30% and 55%.