A forging process for a hip joint femoral stem made of TMZF material

Abstract

The present invention provides a forging process for a hip joint femoral stem made of TMZF material, which can solve the problem of TMZF material grain growth during the forging process, thereby improving the strength and structural reliability of the forged part. The process comprises the following steps: Step 1: heating the TMZF blank, then performing a top forging and bending it according to the part shape, and cooling it to obtain a blank; Step 2: cleaning the blank and spraying a lubricating coating on it; Step 3: pre-forging the sprayed blank; Step 4: cleaning the pre-forged part and spraying a lubricating coating on it; Step 5: final forging the sprayed pre-forged part; and Step 6: heat treating the final forged blank.

Description

Technical Field

[0001] The present invention relates to the technical field of hip joint femoral stem forging, in particular to a forging process of a hip joint femoral stem made of TMZF material. Background Art

[0002] Hip joint femoral stems are artificial joint implants. Currently, most hip joint femoral stems are made of Ti-6Al-4V material. Compared with Ti-6Al-4V alloy, TMZF (Ti-12Mo-6Zr-2Fe) alloy has higher strength, lower elastic modulus, higher fracture toughness and better wear resistance. It is a metastable β titanium alloy. After cooling from the β transformation temperature of 754℃ or higher, the alloy can maintain a full β structure. This full β structure will precipitate fine α phase during the subsequent aging process. However, when using this material to replace Ti-6Al-4V material to make hip joint femoral stems, there are problems such as grain growth during heating and poor mechanical properties during the forging process. Summary of the Invention

[0003] In response to the problem that the grain size of a hip joint femoral stem made of TMZF (Ti-12Mo-6Zr-2Fe) alloy easily grows during the forging process, resulting in a decrease in the mechanical properties of the forging, the present invention provides a forging process for a hip joint femoral stem made of TMZF material, which can solve the problem of grain growth of TMZF material during the forging process, thereby improving the strength and structural reliability of the forging.

[0004] The technical solution is as follows: a TMZF material hip joint femoral stem forging process, characterized in that it includes the following steps: step 1, heating the TMZF blank to 780 ° C - 850 ° C, then performing upsetting forging and bending according to the shape of the part, and obtaining a blank after cooling;

[0005] Step 2: Clean the blank and spray lubricating paint;

[0006] Step 3: Pre-forging the sprayed blank, heating it to 780°C-850°C during the pre-forging process, and cooling it after the pre-forging is completed to obtain a pre-forged part, which has a certain amount of deformation and no deformation dead zone;

[0007] Step 4: Clean the pre-forged parts and spray lubricating paint;

[0008] Step 5: Heat the sprayed pre-forged piece to 780-850°C and perform final forging. After cooling, the final forging piece is obtained. The final forging piece has deformation and no deformation dead zone.

[0009] Step 6: heat treat the blank after final forging at a temperature of 700-770°C, keep it at that temperature for 60-72 minutes, and then place it in a room temperature medium to rapidly cool it at a rate greater than the critical cooling rate;

[0010] The heating time in step 1, step 3 and step 5 is t min ~t max , where t min =k*h max +(1-5) min, where k is the thermal conductivity of the heated part, which is 0.4-0.8 min / mm, h max The thickest dimension of the heated part, in mm, t max =t min + (3-8) min.

[0011] It is further characterized by:

[0012] In step 1, cooling is performed by air cooling, and graphite is used for lubrication during the blank forming process;

[0013] In steps 2 and 4, the coating is a glass lubricant, and after spraying the coating, it is kept at a temperature of 100°C-200°C for 30-240 minutes, and the coating thickness is controlled at 0.08-0.15mm;

[0014] In step 3, the deformation of the pre-forging in the thickness direction is 10%-28%, cooling is carried out by air cooling, and graphite is used for lubrication during the forming process;

[0015] In step five, the deformation of the final forging in the thickness direction is 20%-45%, and the deformation in the width direction is 15%-38%. Cooling is carried out by air cooling, and graphite is used for lubrication during the forming process.

[0016] The beneficial effects of the present invention are as follows: the grain size of the final forgings produced by this scheme can reach level 5 or above, the tensile strength can reach above 1020 MPa, the specified non-proportional elongation strength can reach above 995 MPa, the elongation after fracture is above 17%, the stress performance of the forging along the thickness direction is above 67%, and it has good forging strength and organizational reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a metallographic diagram for grain size assessment at the cross section of the blank after forging heat treatment in Example 1;

[0018] Figure 2 This is a metallographic diagram for grain size assessment at the cross section of the blank after forging heat treatment in Example 2;

[0019] Figure 3 This is the metallographic diagram for grain size assessment at the cross section of the blank after forging heat treatment in Example 3. DETAILED DESCRIPTION

[0020] A forging process for a hip joint femoral stem made of TMZF material is characterized in that it includes the following steps: Step 1, heating the TMZF blank to 780°C-850°C, then performing upsetting forging on it and bending it according to the shape of the part, using graphite for lubrication during the upsetting and bending process, and placing it in room temperature air for cooling to obtain a blank.

[0021] Step 2: Clean the blank and spray lubricating coating. The coating uses glass lubricant. After spraying the coating, keep it at 100℃-200℃ for 30-240min. The coating thickness is controlled at 0.08-0.15mm.

[0022] Step 3: Pre-forge the sprayed blank. During the pre-forging process, heat it to 780℃-850℃. After the pre-forging is completed, air cool it to obtain the pre-forged part. Graphite lubrication is used during the pre-forging process. The deformation of the pre-forged part in the thickness direction is 10%-28%, and there is no deformation dead zone.

[0023] Step 4: Clean the pre-forged parts and spray lubricating coating. The coating uses glass lubricant. After spraying the coating, keep it at 100℃-200℃ for 30-240min. The coating thickness is controlled at 0.08-0.15mm.

[0024] Step 5: Heat the sprayed pre-forged piece to 780-850°C and perform final forging. Graphite is used for lubrication during the final forging process. The final forging piece is placed in room temperature air for cooling to obtain the final forging piece. The final forging piece has deformation. The deformation in the thickness direction of the final forging piece is 20%-45%, and the deformation in the width direction is 15%-38%, and there is no deformation dead zone.

[0025] Step 6: Heat treat the blank after final forging at a temperature of 700-770°C. After holding for 60-72 minutes, place it in a room temperature medium for rapid cooling. The purpose is to allow the final forging to cool rapidly at a rate greater than the critical cooling rate. For example, it can be directly placed in room temperature water (20 degrees) after the insulation is completed.

[0026] Wherein, the heating time in step 1, step 3 and step 5 is t min ~t max , where t min =k*h max +(1-5)min, where k is the thermal conductivity of the heated part, which is 0.4-0.8min / mm, h max The thickest dimension of the heated part, in mm, t max =t min + (3-8) min.

[0027] The following examples demonstrate the performance of forgings:

[0028] Example 1

[0029] 1. Upsetting and bending: A flat forging machine is used to heat, upsetting and bend the TMZF blank according to the shape of the femoral stem. The heating temperature is 780℃-850℃, and the blank is cooled by air cooling at room temperature. Graphite is used for lubrication during the forming process.

[0030] 2. Spray coating: Spray coating on the blank. Before spraying, clean the surface of the blank to ensure that there is no pollutant on the surface; keep it at 150℃ for 100 minutes, use glass lubricant for coating, and the coating thickness is 0.15mm.

[0031] 3. Pre-forging: The forging heating temperature is 780℃-850℃, the heating coefficient is 0.4-0.8min / mm, and the deformation in the thickness direction is 20%.

[0032] 4. Spray coating: Spray coating on the blank. Before spraying, clean the surface of the blank to ensure that there is no pollutant on the surface; keep it warm at 150℃ for 100 minutes, use glass lubricant for coating, and the coating thickness is 0.15mm.

[0033] 5. Final forging: The forging heating temperature is 780℃-850℃, the heating coefficient is 0.4-0.8min / mm, the deformation in the thickness direction is 26%, and the deformation in the width direction is 15%.

[0034] 6. Heat treatment: Heat in a box furnace at a temperature of 700°C-770°C, keep warm for 60min-72min, and then cool by water cooling.

[0035] The metallographic diagram of the grain size evaluation at the cross section of the product obtained after heat treatment is shown in Figure 1 The product performance parameters are shown in Table 1, where Rm refers to tensile strength, Rp0.2 refers to the specified non-proportional extension strength, A refers to the elongation after fracture, and Z refers to the stress performance of the forging along the thickness direction (which can be obtained by doing a tensile test on the specimen, generally measured by the section shrinkage rate).

[0036]

[0037] Example 2

[0038] 1. Upsetting and bending: A flat forging machine is used to heat, upsetting and bend the TMZF blank according to the shape of the femoral stem. The heating temperature is 780℃-850℃, and the blank is cooled by air cooling at room temperature. Graphite is used for lubrication during the forming process.

[0039] 2. Spray coating: Spray coating on the blank. Before spraying, clean the surface of the blank to ensure that there is no pollutant on the surface; keep it at 150℃ for 100 minutes, use glass lubricant for coating, and the coating thickness is 0.08mm.

[0040] 3. Pre-forging: The forging heating temperature is 780℃-850℃, the heating coefficient is 0.4-0.8min / mm, and the deformation in the thickness direction is 27%.

[0041] 4. Spray coating: Spray coating on the blank. Before spraying, clean the surface of the blank to ensure that there is no pollutant on the surface; keep it warm at 150°C for 100 minutes, use glass lubricant for coating, and the coating thickness is 0.08mm.

[0042] 5. Final forging: The forging heating temperature is 780℃-850℃, the heating coefficient is 0.4-0.8min / mm, the deformation in the thickness direction is 22%, and the deformation in the width direction is 38%.

[0043] 6. Heat treatment: Heat in a box furnace at a temperature of 700°C-770°C, keep warm for 60min-72min, and then cool by water cooling.

[0044] The metallographic diagram of the grain size evaluation at the cross section of the product obtained after heat treatment is shown in Figure 2 , product performance parameters are shown in Table 2.

[0045]

[0046] Example 3

[0047] 1. Upsetting and bending: A flat forging machine is used to heat, upsetting and bend the TMZF blank according to the shape of the femoral stem. The heating temperature is 780℃-850℃, and the blank is cooled by air cooling at room temperature. Graphite is used for lubrication during the forming process.

[0048] 2. Spray coating: Spray coating on the blank. Before spraying, clean the surface of the blank to ensure that there are no pollutants on the surface; keep it warm at 150°C for 100 minutes, use glass lubricant for coating, and the coating thickness is 0.11mm.

[0049] 3. Pre-forging: The forging heating temperature is 780℃-850℃, the heating coefficient is 0.4-0.8min / mm, and the deformation in the thickness direction is 10%.

[0050] 4. Spray coating: Spray coating on the blank. Before spraying, clean the surface of the blank to ensure that there is no pollutant on the surface; keep it warm at 150℃ for 100 minutes, use glass lubricant for coating, and the coating thickness is 0.11mm.

[0051] 5. Final forging: The forging heating temperature is 780℃-850℃, the heating coefficient is 0.4-0.8min / mm, the deformation in the thickness direction is 45%, and the deformation in the width direction is 24%.

[0052] 6. Heat treatment: Heat in a box furnace at a temperature of 700°C-770°C, keep warm for 60min-72min, and then cool by water cooling.

[0053] The metallographic diagram of the grain size evaluation at the cross section of the product obtained after heat treatment is shown in Figure 3 , product performance parameters are shown in Table 3.

[0054]

Claims

1. A forging process for a hip joint femoral stem made of TMZF material, characterized in that: It includes the following steps: Step 1: heating the TMZF blank to 780°C-850°C, then performing upsetting and bending according to the shape of the hip joint femoral stem, and obtaining a blank after cooling; Step 2: Clean the blank and spray lubricating paint; Step 3: Pre-forging the sprayed blank, heating it to 780°C-850°C during the pre-forging process, and cooling it after the pre-forging is completed to obtain a pre-forged part, which has a certain amount of deformation and no deformation dead zone; Step 4: Clean the pre-forged parts and spray lubricating paint; Step 5: Heat the sprayed pre-forged piece to 780-850°C and perform final forging. After cooling, the final forging piece is obtained. The final forging piece has deformation and no deformation dead zone. Step 6: heat-treat the blank after final forging at a temperature of 700-770°C, keep the temperature for 60-72 minutes, and then cool it rapidly at a rate greater than the critical cooling rate; The heating time in step 1, step 3 and step 5 is t min ~t max , where t min =k*h max +(1-5) min, where k is the thermal conductivity of the heated part, which is 0.4-0.8 min / mm, h max The thickest dimension of the heated part, in mm, t max =t min + (3-8) min; The TMZF billet is a metastable β titanium alloy, which can maintain a full β structure after cooling from a β transformation temperature of 754°C or higher. The full β structure will precipitate a fine α phase during the subsequent aging process; In step 3, the deformation of the pre-forging in the thickness direction is 10%-28%, cooling is carried out by air cooling, and graphite is used for lubrication during the forming process; In step five, the deformation of the final forging in the thickness direction is 20%-45%, and the deformation in the width direction is 15%-38%. Cooling is carried out by air cooling, and graphite is used for lubrication during the forming process.

2. A forging process for a TMZF hip joint femoral stem according to claim 1, characterized in that: In step 1, cooling is performed by air cooling, and graphite is used for lubrication during the blank forming process.

3. The forging process of a TMZF hip joint femoral stem according to claim 1, characterized in that: In step 2 and step 4, the coating uses glass lubricant, and after spraying the coating, it is kept at a temperature of 100° C.-200° C. for 30-240 minutes, and the coating thickness is controlled at 0.08-0.15 mm.

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