A high-strength and toughness stainless steel wire for ophthalmic scalpels and its preparation method

Abstract

The present invention belongs to the technical field of stainless steel, and specifically relates to a high-strength and toughness stainless steel wire for ophthalmic surgical knives and a preparation method thereof. The content of the precious element Ni is reduced, and the contents of the elements Cu and Ca are increased. By adopting a production process of hot rolling, solid solution, cold rolling, annealing, cold drawing, annealing, cold drawing and low-temperature liquid nitrogen treatment, the stainless steel wire having a precipitated nano-scale copper-rich phase and a fibrous microstructure is produced. The resulting stainless steel wire has a yield strength of 1130 MPa or greater, a tensile strength of 1550 MPa or greater, and an elongation of 35% or greater, meeting the processing requirements of ophthalmic surgical knives.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel, in particular to a high-strength and toughness stainless steel wire for ophthalmic scalpels and a preparation method thereof. Background Art

[0002] Disposable ophthalmic scalpels are essential tools for ophthalmic microsurgery. Their quality plays a critical role in the postoperative outcome, as the sharpness and incision size of the scalpel affect the degree of surgically induced astigmatism. However, these surgical instruments currently on the market suffer from numerous issues, including crude design, poor quality, and insufficient toughness, which create significant inconvenience for physicians. Furthermore, most ophthalmic scalpels are currently made of martensitic stainless steel, resulting in an inefficient and high-cost manufacturing process. This creates significant cost challenges for both manufacturers and patients.

[0003] Austenitic stainless steel, such as 304 stainless steel, which is cheaper than martensitic stainless steel, has high toughness and plasticity, but low strength and cannot be strengthened by phase transformation. It can only be strengthened by cold working. 304 austenitic stainless steel has a strong tendency to work hardening and excellent corrosion resistance. It can be used to make high-strength stainless steel wire. However, after the stainless steel wire is subjected to large deformation during drawing, the high-density grain boundaries, dislocations and other defects produced by the severe plastic deformation seriously limit the subsequent plastic deformation capacity. Shear fracture will occur quickly after the material yields, and the toughness is insufficient. In addition, 304 austenitic stainless steel contains a large amount of Cr elements and has a strong cutting sticking property. When the ophthalmic scalpels made of it are sharpened, built-up edge is generated, making processing difficult and affecting the performance of the ophthalmic scalpels. Therefore, the development of a high-strength and toughness stainless steel wire for ophthalmic scalpels and its preparation method has important practical value. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a high-strength and toughness stainless steel wire for ophthalmic scalpels and a preparation method thereof.

[0005] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0006] A method for preparing a high-strength and high-toughness stainless steel wire for an ophthalmic scalpel comprises the following steps:

[0007] S1. Smelting to obtain a stainless steel ingot; the stainless steel has a Cu content of 1.0-1.5 wt%, a Ca content of ≤1.0 wt%, and a Ni content of 7.0-8.0 wt%;

[0008] S2. After the ingot is kept at 1230-1250℃ for 2-3h, it is immediately hot-rolled in multiple passes to obtain a bar;

[0009] S3, the bar is subjected to solution treatment at a temperature of 1050-1100°C for 2-3 hours, and is immediately cooled after the treatment, and then the surface oxide scale is removed;

[0010] S4, the solution treated bar is subjected to multiple cold rolling passes to obtain a cold rolled bar;

[0011] S5, annealing the cold-rolled bar, and then air-cooling it to room temperature; the annealing temperature is 700-750°C, and the annealing time is 10-100 minutes;

[0012] S6, the annealed bar is subjected to multiple drawing passes to obtain a cold drawn wire;

[0013] S7, annealing the cold drawn wire, and then air cooling to room temperature; the annealing temperature is 200-250°C, and the annealing time is 100-180 minutes;

[0014] S8, the annealed wire is then drawn multiple times to obtain a cold-drawn wire;

[0015] S9. The cold-drawn wire is subjected to ultra-low temperature liquid nitrogen treatment, with the treatment temperature being ≤-100°C and the treatment time being ≥12h, to obtain a stainless steel wire with high strength and toughness for ophthalmic scalpels.

[0016] As a preferred embodiment of the method for preparing a high-strength and toughness stainless steel wire for an ophthalmic scalpel according to the present invention, in step S1, the raw materials are melted in a vacuum induction furnace and then cast to obtain a stainless steel ingot, and the ingot is air-cooled to room temperature before riser removal and surface peeling.

[0017] As a preferred embodiment of the method for preparing a high-strength and toughness stainless steel wire for ophthalmic scalpels according to the present invention, in step S2, the starting rolling temperature is ≥1150°C, and the finishing rolling temperature is ≥950°C.

[0018] As a preferred embodiment of the method for preparing a high-strength and toughness stainless steel wire for ophthalmic scalpels described in the present invention, in step S2, the deformation of a single hot rolling pass is less than 30%, and the total deformation is above 50%. Preferably, the total deformation is 50-60%.

[0019] As a preferred embodiment of the method for preparing a high-strength and toughness stainless steel wire for ophthalmic scalpels described in the present invention, in step S4, the single-pass cold rolling deformation is less than 20%, and the total deformation is above 50%. Preferably, the total deformation is 50-60%.

[0020] As a preferred embodiment of the method for preparing a high-strength and toughness stainless steel wire for ophthalmic scalpels described in the present invention, in step S6, the single-pass cold drawing deformation is less than 15%, and the total deformation is above 60%. Preferably, the total deformation is 60-70%.

[0021] As a preferred embodiment of the method for preparing a high-strength and toughness stainless steel wire for ophthalmic scalpels described in the present invention, in step S8, the single-pass cold drawing deformation is less than 15%, and the total deformation is above 70%. Preferably, the total deformation is 70-80%.

[0022] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0023] A high-strength and toughness stainless steel wire for ophthalmic scalpels is prepared by adopting the above-mentioned method for preparing the high-strength and toughness stainless steel wire for ophthalmic scalpels.

[0024] As a preferred embodiment of the high-strength and toughness stainless steel wire for ophthalmic scalpels described in the present invention, the high-strength and toughness stainless steel wire for ophthalmic scalpels has a yield strength of ≥1130 MPa, a tensile strength of ≥1550 MPa, and an elongation of ≥35%.

[0025] As a preferred embodiment of the high-strength and toughness stainless steel wire for ophthalmic scalpels described in the present invention, the composition of the high-strength and toughness stainless steel wire for ophthalmic scalpels, in terms of mass percentage, includes: C≤0.18wt%, Si≤1.0wt%, S≤0.03wt%, P≤0.02wt%, Mn 2.0-3.0wt%, Cr 17.0-18.0wt%, Ni 7.0-8.0wt%, Cu 1.0-1.5wt%, Ca 0.5-1.0wt%, and the remainder is Fe and unavoidable impurities.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention provides a high-strength and toughness stainless steel wire for ophthalmic surgical knives and a preparation method thereof. The content of the precious element Ni is reduced, and the contents of the elements Cu and Ca are increased. By adopting a production process of hot rolling, solid solution, cold rolling, annealing, cold drawing, annealing, cold drawing and low-temperature liquid nitrogen treatment, the stainless steel wire having a precipitated nano-scale copper-rich phase and a fibrous microstructure is produced. The resulting stainless steel wire has a yield strength of 1130 MPa or greater, a tensile strength of 1550 MPa or greater, and an elongation of 35% or greater, which can meet the processing and application requirements of ophthalmic surgical knives. DETAILED DESCRIPTION

[0028] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0030] A method for preparing a high-strength and high-toughness stainless steel wire for an ophthalmic scalpel comprises the following steps:

[0031] S1. Smelting to obtain a stainless steel ingot; the stainless steel has a Cu content of 1.0-1.5 wt%, a Ca content of ≤1.0 wt%, and a Ni content of 7.0-8.0 wt%;

[0032] S2. After the ingot is kept at 1230-1250℃ for 2-3h, it is immediately hot-rolled in multiple passes to obtain a bar;

[0033] S3, the bar is subjected to solution treatment at a temperature of 1050-1100°C for 2-3 hours, and is immediately cooled after the treatment, and then the surface oxide scale is removed;

[0034] S4, the solution treated bar is subjected to multiple cold rolling passes to obtain a cold rolled bar;

[0035] S5, annealing the cold-rolled bar, and then air-cooling it to room temperature; the annealing temperature is 700-750°C, and the annealing time is 10-100 minutes;

[0036] S6, the annealed bar is subjected to multiple drawing passes to obtain a cold drawn wire;

[0037] S7, annealing the cold drawn wire, and then air cooling to room temperature; the annealing temperature is 200-250°C, and the annealing time is 100-180 minutes;

[0038] S8, the annealed wire is then drawn multiple times to obtain a cold-drawn wire;

[0039] S9. The cold-drawn wire is subjected to ultra-low temperature liquid nitrogen treatment, with the treatment temperature being ≤-100°C and the treatment time being ≥12h, to obtain a stainless steel wire with high strength and toughness for ophthalmic scalpels.

[0040] The present invention reduces the content of precious element Ni in stainless steel and increases the content of element Cu and element Ca. By adopting a production process of hot rolling, solid solution, cold rolling, annealing, cold drawing, annealing, cold drawing and low-temperature liquid nitrogen treatment, a stainless steel wire having a precipitated nano-scale copper-rich phase and a fibrous microstructure is produced.

[0041] Preferably, in step S1, the raw materials are melted in a vacuum induction furnace and then cast to obtain a stainless steel ingot, and the ingot is air-cooled to room temperature before riser removal and surface peeling.

[0042] Preferably, in step S2, the starting rolling temperature is ≥1150°C, and the finishing rolling temperature is ≥950°C.

[0043] Preferably, in step S2, the deformation of a single hot rolling pass is less than 30%, and the total deformation is above 50%. Preferably, the total deformation is 50-60%.

[0044] Preferably, in step S4, the deformation of a single cold rolling pass is less than 20%, and the total deformation is above 50%. Preferably, the total deformation is 50-60%.

[0045] Preferably, in step S6, the deformation of a single cold drawing pass is less than 15%, and the total deformation is above 60%. Preferably, the total deformation is 60-70%.

[0046] Preferably, in step S8, the deformation of a single cold drawing pass is less than 15%, and the total deformation is above 70%. Preferably, the total deformation is 70-80%.

[0047] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0048] A high-strength and toughness stainless steel wire for ophthalmic scalpels is prepared by adopting the above-mentioned method for preparing the high-strength and toughness stainless steel wire for ophthalmic scalpels.

[0049] Preferably, the high-strength and toughness stainless steel wire for ophthalmic scalpels has a yield strength of ≥1130 MPa, a tensile strength of ≥1550 MPa, and an elongation of ≥35%.

[0050] Preferably, the composition of the high-strength and toughness stainless steel wire for ophthalmic scalpels, in mass percentage, includes: C≤0.18wt%, Si≤1.0wt%, S≤0.03wt%, P≤0.02wt%, Mn2.0~3.0wt%, Cr 17.0~18.0wt%, Ni 7.0~8.0wt%, Cu 1.0~1.5wt%, Ca0.5~1.0wt%, and the rest is Fe and unavoidable impurities.

[0051] C: The C element can achieve the purpose of solid solution strengthening by forming interstitial solid solution, adjust the hardness and strength of the material, and does not affect the processing performance of stainless steel.

[0052] Cr: Cr is used to increase the corrosion resistance and improve the oxidation resistance of stainless steel.

[0053] Ni: Ni improves the material's corrosion resistance and increases the strength and toughness of the structure. It also plays a positive role in matching strength and ductility. However, Ni is one of the more expensive alloying elements. Reducing its content can significantly reduce costs, so for comprehensive considerations, the Ni content is controlled at 7.0-8.0 wt%.

[0054] Mn: Mn is used to improve the toughness and strength of the material, allowing it to achieve a work-hardening effect during subsequent cold working. In addition, Mn has a strong affinity with S, easily forming MnS, thereby reducing the harmful effects of S in steel.

[0055] Cu: The addition of Cu improves the strength and wear resistance of steel, as well as its antibacterial properties. However, excessive Cu can lead to copper embrittlement and deteriorate the material's processing properties, while too low a Cu content can weaken the stainless steel's antibacterial properties. Therefore, the Cu content should be controlled between 1.0 and 1.5 wt% to ensure a balance between formability and corrosion resistance.

[0056] Ca: It is used to improve the strength of the material and increase the machinability of the material. However, excessive Ca will bring harmful inclusions, reduce strength and toughness, and increase production costs. Therefore, considering all factors, the Ca content should be controlled at 0.5-1.0wt%.

[0057] The technical solution of the present invention is further described below with reference to specific embodiments.

[0058] The chemical compositions of the stainless steels of the embodiments of the present invention and the comparative examples are shown in Table 1.

[0059] Table 1 Chemical composition of stainless steel in various embodiments and comparative examples (wt%)

[0060]

[0061] The main production process parameters of the stainless steel of each embodiment of the present invention and the comparative example are shown in Table 2.

[0062] Table 2 Production process parameters of stainless steel in various embodiments and comparative examples

[0063]

[0064] Standard tensile specimens were prepared according to GB / T 228.1-2021 "Tension Tests on Metallic Materials - Part 1: Room Temperature Test Methods," and then subjected to room temperature mechanical testing. The properties of the stainless steels of the various embodiments and comparative examples of the present invention are shown in Table 3.

[0065] Table 3 Properties of stainless steel in various embodiments and comparative examples

[0066] Yield strength / MPa Tensile strength / MPa Elongation / % Example 1 1132 1560 38 Example 2 1147 1590 39 Example 3 1135 1573 41 Comparative Example 1 920 1112 22 Comparative Example 2 942 1148 31 Comparative Example 3 902 1013 18 Comparative Example 4 918 1106 21 Comparative Example 5 986 1264 27

[0067] The present invention reduces the content of the precious element Ni and increases the content of the elements Cu and Ca. By adopting a production process of hot rolling, solid solution, cold rolling, annealing, cold drawing, annealing, cold drawing and low-temperature liquid nitrogen treatment, a stainless steel wire having a precipitated nano-scale copper-rich phase and a fibrous microstructure is produced. The yield strength of the finally produced stainless steel wire is ≥1130 MPa, the tensile strength is ≥1550 MPa, and the elongation is ≥35%, which can meet the processing application requirements of ophthalmic surgical tools.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing high-strength and high-toughness stainless steel wire for ophthalmic scalpels, characterized in that: The steps include: S1, smelting to obtain stainless steel ingot; S2. After the ingot is kept at 1230-1250℃ for 2-3h, it is immediately hot-rolled in multiple passes to obtain bars; S3, the bar is subjected to solution treatment at a temperature of 1050-1100°C for 2-3 hours, and is immediately cooled after the treatment, and then the surface oxide scale is removed; S4, the solution treated bar is subjected to multiple cold rolling passes to obtain a cold rolled bar; S5, annealing the cold-rolled bar, and then air-cooling it to room temperature; the annealing temperature is 700-750°C, and the annealing time is 10-100 minutes; S6, the annealed bar is subjected to multiple drawing passes to obtain a cold drawn wire; S7, annealing the cold drawn wire, and then air cooling to room temperature; the annealing temperature is 200-250°C, and the annealing time is 100-180 minutes; S8, the annealed wire is then drawn multiple times to obtain a cold-drawn wire; S9, subjecting the cold-drawn wire to ultra-low temperature liquid nitrogen treatment, with the treatment temperature being ≤-100°C and the treatment time being ≥12h, to obtain a high-strength and toughness stainless steel wire for ophthalmic surgical knives; The composition of the high-strength and toughness stainless steel wire for ophthalmic scalpels includes, by mass percentage, C≤0.18wt%, Si≤1.0wt%, S≤0.03wt%, P≤0.02wt%, Mn 2.0~3.0wt%, Cr 17.0~18.0wt%, Ni 7.0~8.0wt%, Cu 1.0~1.5wt%, Ca 0.5~1.0wt%, and the rest is Fe and unavoidable impurities.

2. The method for preparing a high-strength and toughness stainless steel wire for ophthalmic surgical knives according to claim 1, characterized in that: In step S2, the starting rolling temperature is ≥1150°C, and the finishing rolling temperature is ≥950°C.

3. The method for preparing a high-strength and toughness stainless steel wire for ophthalmic surgical knives according to claim 1, characterized in that: In step S2, the deformation of a single hot rolling pass is less than 30%, and the total deformation is greater than 50%.

4. The method for preparing a high-strength and toughness stainless steel wire for ophthalmic surgical knives according to claim 1, characterized in that: In step S4, the deformation of a single cold rolling pass is less than 20%, and the total deformation is greater than 50%.

5. The method for preparing a high-strength and toughness stainless steel wire for ophthalmic surgical knives according to claim 1, characterized in that: In step S6, the deformation of a single cold drawing pass is less than 15%, and the total deformation is greater than 60%.

6. The method for preparing a high-strength and toughness stainless steel wire for ophthalmic surgical knives according to claim 1, characterized in that: In step S8, the deformation of a single cold drawing pass is less than 15%, and the total deformation is above 70%.

7. A high-strength and toughness stainless steel wire for ophthalmic surgical knives, characterized in that: The stainless steel wire is prepared by the method for preparing high-strength and toughness stainless steel wire for ophthalmic scalpels according to any one of claims 1 to 6.

8. The high-strength and toughness stainless steel wire for ophthalmic surgical knives according to claim 7, characterized in that: The high-strength and toughness stainless steel wire for ophthalmic surgical knives has a yield strength of ≥1130 MPa, a tensile strength of ≥1550 MPa, and an elongation of ≥35%.

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