CN111778454A

CN111778454A - Stainless steel for surgical instrument and method for manufacturing same

Info

Publication number: CN111778454A
Application number: CN202010795088.6A
Authority: CN
Inventors: 张鑫
Original assignee: Changshu Institute of Technology
Current assignee: Changshu Institute of Technology
Priority date: 2020-08-10
Filing date: 2020-08-10
Publication date: 2020-10-16

Abstract

The invention relates to stainless steel for surgical instruments, which comprises the following components in percentage by weight: c: 0.15-0.90%, N: 0.07 to 0.25%, Mn: 2.0-2.5%, Cr: 13.5 to 18.0%, Mo: 0.5 to 2.5%, Ni: 0.2 to 1.2% and contains Cr, Mo, N, C, Mn and Ni in the ranges satisfying the following formulae (A), (B) and (C), with the balance being Fe and other unavoidable impurities, Cr +4.5Mo +20N being not less than 20(A), C + N being not less than 0.55(B), Mn + Ni +10N being not less than 3 (C). The stainless steel for surgical instruments can improve the pitting corrosion resistance equivalent and pitting corrosion resistance potential of the material under the condition of ensuring the same hardness by alloying design of Mo and N in a special proportion, so as to obtain a material with higher corrosion resistance.

Description

Stainless steel for surgical instrument and method for manufacturing same

Technical Field

The invention relates to the technical field of stainless steel, in particular to stainless steel for surgical instruments and a manufacturing method thereof.

Background

The stainless steel for the surgical instruments is mainly used for the surgical instruments, and comprises surgical scissors, forceps, a lead, forceps, a surgical platform, a surgical trolley, medical refrigeration equipment and the like. Surgical instruments, which typically require special requirements in terms of strength, hardness, stiffness, toughness, wear and corrosion resistance, are typically made from martensitic and austenitic stainless steels.

Currently, surgical instrument failures are often inadequate sharpness and rusting or incomplete closure, reduced performance. The phenomenon that the sharpness is insufficient due to the abrasion of the surgical instrument is inevitable, but the hardness of the material and the distribution of hard particles have a remarkable influence on the abrasion degree, and the low hardness inevitably causes the accelerated abrasion to cause the rejection of the instrument. The rusting is an important problem faced by surgical instruments, and the internal reason of the rusting of the materials is that the surgical instruments contact with blood in the using process, NaCl, hemoglobin and the like in the blood have certain corrosivity, and the instruments are easy to corrode in the long-time surgical process; the external reasons of rusting are incomplete cleaning, organic matter corrosion, natural oxidation and the like which damage a passivation film on the surface of stainless steel, so that instruments rust. Therefore, first, the corrosion resistance of stainless steel for surgical instruments should be improved so that the occurrence and degree of corrosion of the instruments during use and daily storage are reduced; secondly, the uniform distribution of hard particles is optimized while high hardness is ensured, the uniformity of hardness is improved, and the sharpness of the cutting edge is ensured.

The instrument is gradually deformed in the using process due to insufficient toughness and the like, and the requirement of closure cannot be met, so that the service life and the using effect of the surgical instrument are influenced. The existing martensitic stainless steel has high hardness and high strength, but has poor plasticity and toughness, and can only be scrapped once deformation occurs. In particular, in the application environments such as bone clamps which require rigidity and toughness, the risk of fracture in operation is high. Therefore, the toughness of the material should be improved while ensuring the hardness, so as to avoid incomplete closure caused by deformation of the instrument.

In addition, surgical instruments require special maintenance and upkeep during the intraoperative and daily storage, and are stored in a dry, neutral environment. Once rusting occurs, a complicated rust removal treatment is required. In addition, medical instruments are required to be sterilized in the using process, the medical instruments are sterilized through high temperature or sterilization treatment, hospitals with limited conditions avoid rusting of surgical instruments, the instruments are protected by paraffin oil, and sterilization failure is easy to cause or the paraffin oil enters human tissues in the operation.

Disclosure of Invention

In view of the defects in the prior art, one of the technical problems to be solved by the present invention is to provide a stainless steel for surgical instruments, which can improve the strength, hardness and corrosion resistance of the material.

The second technical problem to be solved by the invention is to provide a manufacturing method of stainless steel for surgical instruments, which is used for improving the strength, hardness and corrosion resistance of the produced stainless steel material.

In order to solve one of the above technical problems, the present invention provides a stainless steel for surgical instruments, which comprises the following components by weight: c: 0.15-0.90%, N: 0.07 to 0.25%, Mn: 2.0-2.5%, Cr: 13.5 to 18.0%, Mo: 0.5 to 2.5%, Ni: 0.2 to 1.2% and contains Cr, Mo, N, C, Mn and Ni in the ranges satisfying the following formulae (A), (B) and (C), with the balance being Fe and other unavoidable impurities, Cr +4.5Mo +20N being not less than 20(A), C + N being not less than 0.55(B), Mn + Ni +10N being not less than 3 (C).

The stainless steel for surgical instruments can improve the pitting corrosion resistance equivalent and pitting corrosion resistance potential of the material under the condition of ensuring the same hardness by alloying design of Mo and N in a special proportion, obtains the material with higher corrosion resistance, improves the pitting corrosion resistance equivalent and the pitting corrosion resistance potential by more than 30 percent compared with the conventional 20Cr13 and 30Cr13, can precipitate a certain amount of fine nitrides in the material after the N alloying design, improves the uniformity of the material structure and hardness, and is also beneficial to improving the corrosion resistance of the material.

Preferably, the stainless steel for surgical instruments of the present invention further includes, in weight percent, V: 0.15 to 0.30 percent. The V with the weight percentage increased can refine crystal grains, stabilize the structure and improve the hardness of steel.

Preferably, the stainless steel for surgical instruments of the present invention further includes, in weight percent, Cu: 0.005-0.02%, Nb: 0.5% or less, Ti: 0.5% or less, Al: 0.5% or less of one or more. After the components are added, deformation induced martensite phase transformation strengthening and precipitation strengthening of second phase particles such as Cu, Nb, Ti, Al and the like can be combined, so that the material has a composite structure of austenite, martensite and dispersion strengthening particles, and the material has high strength and excellent ductility and toughness.

Preferably, the stainless steel for surgical instruments of the present invention further includes, in weight percent, Si: 0.05 to 0.45 percent.

Preferably, the stainless steel for surgical instruments of the present invention further includes, in weight percent, S: 0.01% or less, P: 0.03% or less of one or two.

Preferably, the stainless steel for surgical instruments of the present invention further includes Ag: less than 0.5 percent. The Ag alloying can make the steel obtain antibacterial property, the Ag-containing material has excellent antibacterial property to almost all bacteria through a plurality of action mechanisms without special antibacterial heat treatment, and the antibacterial property evaluation shows that the antibacterial property is more than or equal to 98 percent.

In order to solve the second technical problem, the invention provides a method for manufacturing stainless steel for surgical instruments, which comprises the following steps: step 1: preparing a steel billet or a continuous casting billet according to the components of the stainless steel for the surgical instrument, hot-rolling the steel billet or the continuous casting billet to prepare a hot-rolled steel plate or a steel strip, and annealing; step 2: heating the annealed steel plate or steel strip to 880-1000 ℃, preserving heat for 5-30 min, and then rapidly cooling to a martensite and austenite two-phase region at a speed of more than 35 ℃/s; and step 3: and (3) heating the cooled steel plate or steel strip to 180-220 ℃, preserving heat for 10-30 min, and then air-cooling to room temperature to form a martensite-austenite complex phase structure with the content of residual austenite phase being 10-20%.

The yield strength of the steel manufactured by the manufacturing method is 300-500MPa, the tensile strength is 400-700MPa, and the elongation can reach 20-35%; the quenching treatment can obtain excellent mechanical properties, the hardness after quenching is 50-55HRC, and the impact energy is more than 30J.

Detailed Description

The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.

The embodiment provides stainless steel for surgical instruments, which comprises the following components in percentage by weight: c: 0.15-0.90%, N: 0.07 to 0.25%, Mn: 2.0-2.5%, Cr: 13.5 to 18.0%, Mo: 0.5 to 2.5%, Ni: 0.2-1.2%, and the contents of Cr, Mo, N, C, Mn and Ni are required to meet the requirements that Cr +4.5Mo +20N is more than or equal to 20, C + N is more than or equal to 0.55, Mn + Ni +10N is more than or equal to 3, and the balance is Fe and other inevitable impurities.

Referring to table 1, steel materials corresponding to steel grades 1, 2 and 3 are example one, example two and example three of the present application, and steel materials corresponding to steel grades D1 and D2 are comparative example one and comparative example two of the present application.

According to the weight percentage of each element (the balance being Fe and other inevitable impurities), the finished product steel is obtained by processing according to the following steps:

step 1: according to the weight percentage of each element, a steel billet or a continuous casting billet is prepared, and the steel billet or the continuous casting billet is hot-rolled to prepare a hot-rolled steel plate or a steel strip and is annealed;

step 2: heating the annealed steel plate or steel strip to 950 ℃, preserving the heat for 20min, and then rapidly cooling the steel plate or steel strip to a martensite and austenite two-phase region at the speed of more than 35 ℃/s;

and step 3: and (3) heating the cooled steel plate or steel strip to 200 ℃, preserving heat for 20min, and then air-cooling to room temperature to form a martensite and austenite complex phase structure, wherein the content of the residual austenite phase is 10-20%.

TABLE 1

As can be seen from Table 1, the yield strength, tensile strength and pitting potential after annealing, hardness after quenching and impact energy of the steels according to examples 1, 2 and 3 are all much better than those of the steels according to comparative examples 1 and 2, and it can be seen that the weight percentage design of each element of this example has an excellent effect of improving the properties of the steels, and further, the higher the contents of Cr and Ni, the higher the pitting potential of the steels, i.e., the better the corrosion resistance.

Further, the stainless steel for surgical instruments may further include: v: 0.15-0.30%, Cu: 0.005-0.02%, Nb: 0.5% or less, Ti: 0.5% or less, Al: 0.5%, Si: 0.05-0.45%, S: 0.01% or less, P: 0.03%, Ag: less than 0.5% of one or more of the above-mentioned materials. To further illustrate the effect of adding other elements on the properties of the steel, example one is a comparative example, and other element components are added in corresponding proportions based on example 1 according to table 2 to form examples 4, 5, 6, 7, 8, 9, i.e., examples 4 to 9, all containing C: 0.52%, N: 0.07%, Mn: 2%, Cr: 18%, Mo: 1.6%, Ni: 1.2% and examples 4-9 were all processed as described above.

TABLE 2

In examples 4 to 10, P: 0.03% or less and 0.01% or less.

As can be seen from table 2, in example 4, although the yield strength is reduced by 5.26% by increasing V by 0.15% based on example 1, the pitting potential is greatly increased by 57.14%, the hardness is increased by 7.84%, and the impact energy is increased by 9.09%.

Example 5 the yield strength, tensile strength and impact strength were improved by 2.78%, 5.77% and 8.33% by adding 0.05% Si to example 4, respectively, and it is seen that the addition of Si element can suitably improve the strength of the steel while maintaining a high pitting potential.

The contents of V and Si of examples 6 and 7 are gradually increased, wherein V can improve the corrosion resistance of the steel and Si can improve the yield strength and tensile strength of the steel.

Examples 8, 9 and 10 were made in addition to example 6 with Cu, Nb, Ti and Al, and it can be seen that the steel materials according to examples 8, 9 and 10 significantly improved the impact energy, that is, the toughness, on the basis of the steel material according to example 4.

If the stainless steel material in this application is used in the higher product production of bacterinertness requirement, like wire, director, clamp etc. can increase Ag: less than 0.5 percent, endows the stainless steel with antibacterial property by Ag alloying, evenly distributes Ag in the stainless steel in the form of simple substance, and can effectively kill almost all bacteria by various composite actions such as electrostatic adsorption, dissolution combination, photocatalysis, and the like.

In step 2 of the method for processing a steel material according to the present embodiment, the annealed steel sheet or strip may be heated to 880 ℃ (1000 ℃) and held for 5min (30 min); in step 2, the cooled steel plate or strip may be reheated to 180 ℃ (220 ℃) and kept warm for 10min (30min), and then air-cooled to room temperature to form a martensite + austenite complex phase structure, wherein the higher the heating temperature and the longer the keeping warm time, the closer the austenite content is to 20%.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; these modifications and substitutions do not cause the essence of the corresponding technical solution to depart from the scope of the technical solution of the embodiments of the present invention, and are intended to be covered by the claims and the specification of the present invention.

Claims

1. The stainless steel for the surgical instrument is characterized by comprising the following components in percentage by weight:

c: 0.15-0.90%, N: 0.07 to 0.25%, Mn: 2.0-2.5%, Cr: 13.5 to 18.0%, Mo: 0.5 to 2.5%, Ni: 0.2 to 1.2% and Cr, Mo, N, C, Mn and Ni in the range satisfying the following formulae (A), (B) and (C), and the balance Fe and other unavoidable impurities,

Cr+4.5Mo+20N≥20(A)，

C+N≥0.55(B)，

Mn+Ni+10N≥3(C)。

2. the stainless steel for surgical instruments according to claim 1, wherein:

and by weight percentage, the material also comprises V: 0.15 to 0.30 percent.

3. A stainless steel for surgical instruments according to claim 1 or 2, wherein:

the alloy also comprises Cu: 0.005-0.02%, Nb: 0.5% or less, Ti: 0.5% or less, Al: 0.5% or less of one or more.

4. A stainless steel for surgical instruments according to claim 1, 2 or 3, wherein:

the alloy also comprises the following components in percentage by weight: 0.05 to 0.45 percent.

5. A stainless steel for surgical instruments according to any one of claims 1 to 4, wherein:

the composite material also comprises S: 0.01%, P: 0.03% or less of one or two.

6. A stainless steel for surgical instruments according to any one of claims 1 to 5, wherein:

the material also comprises Ag: less than 0.5 percent.

7. A method for manufacturing stainless steel for surgical instruments is characterized by comprising the following steps:

step 1: the stainless steel for surgical instruments as set forth in claim 1, which is formed into a steel slab or a continuous cast slab, and hot-rolled into a hot-rolled steel sheet or a steel strip, and annealed;

step 2: heating the annealed steel plate or steel strip to 880-1000 ℃, preserving heat for 5-30 min, and then rapidly cooling to a martensite and austenite two-phase region at a speed of more than 35 ℃/s;

and step 3: and (3) heating the cooled steel plate or steel strip to 180-220 ℃, preserving heat for 10-30 min, and then air-cooling to room temperature to form a martensite-austenite complex phase structure with the content of residual austenite phase being 10-20%.