CN113088868A - Salt bath nitriding formula and processing method of martensitic stainless steel medical suture needle - Google Patents
Salt bath nitriding formula and processing method of martensitic stainless steel medical suture needle Download PDFInfo
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- CN113088868A CN113088868A CN202110395013.3A CN202110395013A CN113088868A CN 113088868 A CN113088868 A CN 113088868A CN 202110395013 A CN202110395013 A CN 202110395013A CN 113088868 A CN113088868 A CN 113088868A
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/40—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions
- C23C8/42—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions only one element being applied
- C23C8/48—Nitriding
- C23C8/50—Nitriding of ferrous surfaces
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/26—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for needles; for teeth for card-clothing
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F17/00—Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25
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Abstract
The invention discloses a salt bath nitriding formula of a martensitic stainless steel medical suture needle and a processing method thereof. By using CO (NH)2)2、Na2CO3、K2CO3、Li2CO3、K2SO3、KCl、CeCO3、Y2(CO3)3And Sr (OH)2The low-temperature nitriding treatment of the medical martensitic stainless steel suture needle is realized by using the salt bath nitriding formula. The melting point temperature of the salt bath nitriding formula is lower than 450 ℃, and when the salt bath nitriding formula is used at the temperature of 450-550 ℃, the salt bath has good fluidity. The martensite stainless steel wire (the hardness is less than or equal to HV280) in a soft state is processed and formedAfter the suture needle is quenched and nitrided by the salt bath formula, a nitriding layer is formed on the needle point and the surface of the suture needle, and the suture needle has high hardness (HV580-680), high wear resistance and high corrosion resistance, and quenched martensite has higher toughness after being tempered at 450-500 ℃.
Description
Technical Field
The technology relates to a processing technology of a medical suture needle, in particular to a surface treatment technology of a martensite stainless steel medical suture needle, namely a salt bath nitriding formula and a using method thereof. The technology is used for improving the hardness and sharpness of the surface and the needle point of the martensitic stainless steel medical suture needle while keeping higher toughness.
Background
The medical stainless steel has become a medical implant material and a material for medical instruments widely used in clinic due to good biocompatibility, mechanical property, body fluid corrosion resistance, excellent processing and forming properties and low cost. Medical suture needles are very common and frequently used instruments in surgical operations, and are mostly manufactured by drilling or slotting a needle tail which uses stainless steel wires as raw materials. Different from instruments applied to non-living bodies, the medical suture needle is used for suturing human tissues in surgical operations, and has requirements on performance including difficult deformation, high elasticity, high toughness and high hardness of a needle tip so as to have higher sharpness besides the size and the shape.
Stainless steel for medical suture needles mainly comprises martensitic stainless steel and austenitic stainless steel. The martensitic stainless steel mainly comprises 2Cr13, 3Cr13, 4Cr13, 420J2 stainless steel and the like. The austenitic stainless steel mainly includes 12Cr18Ni9, 06Cr19Ni10 and the like.
In the medical suture needle standard (YY/T0043-2016) in the Chinese medical industry, the requirements of the medical suture needle performance mainly comprise two aspects of physical performance and corrosion resistance. The physical property requirements of the medical suture needle mainly comprise (1) hardness, and the needle point of the suture needle has higher hardness. The hardness of the martensite stainless steel medical suture needle is more than or equal to HV 520. (2) The elasticity of the sewing needle is good, and the sewing needle can recover after a certain amount of deformation. (3) The toughness, the suture needle should have good toughness, and the fracture does not occur in the toughness test. (4) The shape of the needle point is the same as that of a virtual needle point, and the needle point is not hooked after being loaded and pressed by a load at a stress application speed specified by YY/T0043-2016. (5) The suture needle has the requirement of corrosion resistance, and the surface state of the suture needle is not lower than the 5.4 b-level regulation in YY/T0149-2006.
Martensite type stainless steel suture needles such as 2Cr13, 3Cr13 and 4Cr13 can be improved in hardness and sharpness by obtaining martensite by quenching. The martensite stainless steel suture needle is made of soft steel wire, so that the suture needle can be processed and molded conveniently, such as bending and pinhole processing, after the processing and molding, the hardness and sharpness of the needle point of the suture needle are improved through quenching, and finally certain toughness is obtained through tempering. Under the process condition, in order to ensure higher hardness (not less than HV 520) and sharpness of the needle point of the suture needle, low-temperature tempering (heating temperature is not more than 250 ℃) is generally adopted, because the hardness and the sharpness of the needle point are reduced along with the rise of tempering temperature although the toughness of the suture needle is gradually increased, and the requirements on the hardness (not less than HV 520) and sharpness of the needle point are difficult to achieve.
The surface nitriding technology can effectively improve the hardness, the wear resistance and the corrosion resistance of the needle point part and the surface of the stainless steel suture needle by forming a nitriding layer on the surface, and simultaneously keeps the internal toughness. Wherein, liquid nitriding is a chemical heat treatment technology which causes active nitrogen atoms to permeate into a metal surface layer in a certain medium at a certain temperature to change the structure and the performance of the surface layer. The liquid nitriding, also known as salt bath nitriding, can strengthen the surface of stainless steel and improve the wear resistance, hardness, corrosion resistance and fatigue resistance. The liquid nitriding process has the characteristics of uniform heating, less deformation, quick heating, wide application range and the like.
Disclosure of Invention
The invention provides a salt bath nitriding formula and a processing method of a martensitic stainless steel medical suture needle, wherein a nitriding technology is adopted, and the conditions that the surface of martensitic stainless steel is poor in chromium due to overhigh conventional nitriding temperature, the corrosion resistance is reduced and the hardness is remarkably reduced due to the high-temperature tempering action of martensite are avoided after nitriding in a certain temperature range.
According to a first aspect of the invention, there is provided a salt bath formulation for low temperature salt bath nitriding of martensitic stainless steel, the composition of the salt bath formulation comprising CO (NH)2)2、Na2CO3、K2CO3、Li2CO3、K2SO3、KCl、CeCO3、Y2(CO3)3And Sr (OH)2。
Preferably, the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2：15％-30％
Na2CO3：10-20％
K2CO3：15-30％
Li2CO3：5-10％
Na2SO3：2-10％
KCl：5-15％
CeCO3：2-4％
Y2(CO3)3：2-4％
Sr(OH)2：4-8％。
further preferably, the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2：25％，Na2CO3：15％，K2CO3：25％，Li2CO3：7％，Na2SO3：6％，KCl：10％，CeCO3：3％，Y2(CO3)3：3％，Sr(OH)2：6％。
the invention adds strontium hydroxide to increase the activity of the nitride salt and reduce the melting point of the nitride salt.
In the using process, the reaction principle of each component in the low-temperature salt bath nitriding salt bath is as follows:
the reaction occurs when the nitride salt is melted in the low-temperature salt bath nitridation
2CO(NH2)2+CO3 2﹣→2CNO﹣+2NH3↑+H2O↑+CO2↑
The cyanate low-temperature salt bath nitriding decomposition mainly comprises the following four reactions:
4CNO﹣→CO3 2﹣+2CN﹣+CO↑+2[N] (1)
2CNO﹣+O2→CO3 2﹣+CO↑+2[N] (2)
2CN﹣+O2→2CNO﹣ (3)
2CO→CO2 (4)
reaction (1) takes place preferentially at high temperatures, but this reaction produces CN﹣，CN﹣Toxic and therefore this reaction is avoided as much as possible. The reaction (2) is free from generating toxic substances at low temperature, and can meet the use requirements of the martensitic stainless steel.
Added Na2CO3、K2CO3、CeCO3、Y2(CO3)3、CO(NH2)2Used for generating cyanate ions required by low-temperature salt bath nitriding, and the joint use of a plurality of carbonates helps to obtain higher CO3 2﹣Ion and active nitrogen ion concentrations; k2SO3Used for controlling the content of generated cyanide; li+The method has the advantages that the infiltration is promoted in the nitriding process, and the melting point of the salt bath can be reduced; KC1 provides a basic environment for a neutral salt bath, is used in cooperation with the neutral salt bath, enables the reaction to be carried out smoothly, and is helpful for adjusting the melting point; the strontium hydroxide can improve the activity of the salt bath, and improve the stability of the salt bath and the stability of basic components; meanwhile, the strontium ions have better bioactivity and can meet the use requirement of the martensitic stainless steel as a medical suture needle. The melting point of the low-temperature salt bath nitriding and nitriding salt is not higher than 450 ℃.
According to a second aspect of the present invention, there is provided a method for processing a martensitic stainless steel medical suture needle, comprising the steps of:
the method comprises the following steps:
the martensitic stainless steel wire is cold-drawn to the required specifications with different diameters, the annealing hardness is less than or equal to HV280, and the martensitic stainless steel wire is uncoiled, straightened, cut off, processed by a pinhole, processed by a needle point and bent to realize the processing and forming of the medical suture needle.
Step two:
the martensitic stainless steel suture needle is heated and then quenched. The heating temperature is set according to the specific steel type, and a water quenching mode or an oil quenching mode can be adopted, and the oil quenching mode is preferably adopted.
Step three:
1) salt bath nitriding: by adopting the salt bath formula of the low-temperature salt bath nitriding of the first aspect of the invention, all components are uniformly stirred, heated to 450 ℃, and the temperature is preserved to completely melt all components of the salt bath; performing salt bath treatment on the martensitic stainless steel suture needle, wherein the treatment temperature is between 450 ℃ and 500 ℃, the nitriding time is 20-60min according to the diameter size of the suture needle, and taking out the suture needle after the salt bath for air cooling.
2) Cleaning and drying: cleaning the stainless steel suture needle treated in the step 1) with water and then drying.
The salt bath nitriding formula of the martensitic stainless steel medical suture needle and the processing method thereof also have the following advantages.
Firstly, compared with the traditional martensitic stainless steel medical suture needle treatment process, the salt bath nitriding treatment adopted by the invention can obtain a medical suture needle product with better comprehensive performance. The traditional martensitic stainless steel medical suture needle treatment process adopts quenching and low-temperature tempering, and in the tempering process, along with the rise of temperature, the toughness of the material is increased, but the hardness and the sharpness of a needle point are reduced, so that in order to enable the hardness and the sharpness of the suture needle to meet the requirements (not more than HV 520), only low-temperature tempering (not more than 300 ℃) can be adopted, but the toughness after tempering is poor, and a great brittle failure risk exists. The invention adopts liquid nitriding at 450-550 ℃ after quenching, the hardness of the needle point part and the needle body surface is improved to HV580-680 due to the nitriding layer formed after nitriding treatment, and the hardness of the quenched martensite at the core part is reduced to HV300-400 after medium temperature tempering, so that the hardened martensite has higher toughness, and the contradiction among high hardness, high sharpness and high toughness of a single martensite structure is solved. After the suture needle is treated by the method, the needle point and the needle surface have high hardness and high sharpness, and the needle body of the suture needle has higher toughness, so that the brittle failure tendency of the suture needle can be obviously reduced.
Secondly, the melting point of the salt bath nitriding formula is lower, the melting point temperature of the formula is lower than 450 ℃, and the salt bath has good fluidity at the temperature of 450-2+And Li+Plays a role in promoting the penetration in the nitriding process. The conventional liquid nitriding treatment temperature is high (generally above 600 ℃), chromium atoms in stainless steel are easy to combine with active nitrogen atoms at high temperature to generate chromium and nitrogen compounds which are separated out at a martensite grain boundary of a nitriding layer, so that chromium is poor on the surface layer, and the corrosion resistance of the stainless steel is reduced. Therefore, the stainless steel after the salt bath nitriding treatment of the present invention has higher corrosion resistance than the conventional liquid nitriding treatment. Secondly, the salt bath nitriding formula of the formula is used at a relatively low temperature, so that toxic substances CN easily generated by cyanate at high temperature are avoided﹣The harm to the environment and personnel is reduced.
Detailed Description
The technical solutions in the embodiments of the present invention will be specifically described below with reference to specific embodiments of the present invention, and the following descriptions are only a part of the embodiments of the present invention, but not all of the embodiments. The salt bath formulation and nitriding techniques of the present invention are described below using 420J2 stainless steel as an example. The present invention is suitable for all martensitic stainless steels, and is not limited to 420J2 stainless steel. In each example, the 420J2 stainless steel wire was first processed as follows:
the method comprises the following steps: and (3) cold-drawing the 420J2 stainless steel wire to the required specifications with different diameters, and annealing to ensure that the hardness is less than or equal to HV 280. The martensitic stainless steel wire is processed and molded by the procedures of uncoiling, straightening, cutting, pinhole processing, needle point processing, bending and the like.
Step two: heating the suture needle processed in the step one to 1050 +/-20 ℃, and then carrying out oil quenching.
Step three: the needle point of the suture needle is finely repaired to achieve the sharp needle point without a virtual point. And (4) surface polishing, namely performing chemical (common acid washing) or electrochemical surface polishing treatment on the suture needle treated by the steps.
Step four: and cleaning the suture needle with the polished surface, and drying the cleaned suture needle.
Example 1
The annealing hardness of the 420J2 stainless steel wire is HV270, and after pre-processing, the salt bath formula of the following low-temperature salt bath nitriding formula is adopted, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,15％
Na2CO3，15
K2CO3，30％
Li2CO3，10％
Na2SO3，10％
KCl，5％
CeCO3，4％
Y2(CO3)3，4％
Sr(OH)2，7％
the 420J2 martensitic stainless steel is subjected to salt bath nitriding treatment by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly, heated to 450 ℃, and kept warm to completely melt the components in the salt bath.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at the treatment temperature of 450 ℃ for 20min, taking out the suture needle after the salt bath, and performing air cooling.
3) Cleaning and drying; cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The detection proves that the nitriding layer depth of the 420J2 stainless steel suture needle is 8 +/-2 mu m, and the surface hardness is HV580 +/-30.
Example 2
The annealing hardness of the 420J2 stainless steel wire is HV260, and after pre-processing, the salt bath formula of the following low-temperature salt bath nitriding formula is adopted, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,30％
Na2CO3，20％
K2CO3，20％
Li2CO3，5％
Na2SO3，2％
KCl，15％
CeCO3，2％
Y2(CO3)3，2％
Sr(OH)2，4％
the 420J2 martensitic stainless steel is subjected to salt bath nitriding treatment by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly, heated to 450 ℃, and kept warm to completely melt the components in the salt bath.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at the treatment temperature of 460 ℃ for 30min, taking out the martensitic stainless steel suture needle after the salt bath treatment, and air-cooling the martensitic stainless steel suture needle.
3) Cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The 420J2 stainless steel suture needle was tested to have a nitriding layer depth of 10 + -2 μm and a surface hardness of HV610 + -35.
Example 3
The annealing hardness of the 420J2 stainless steel wire is HV280, and after pre-processing, the salt bath formula of the following low-temperature salt bath nitriding formula is adopted, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,30％
Na2CO3，10％
K2CO3，20％
Li2CO3，10％
Na2SO3，7％
KCl，10％
CeCO3，3％
Y2(CO3)3，2％
Sr(OH)2，8％
the salt bath nitriding treatment is carried out on the 420J2 martensitic stainless steel suture needle by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly and heated to 450 ℃ for heat preservation so that the components in the salt bath are completely melted.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at the treatment temperature of 470 ℃, nitriding for 40min, taking out the suture needle after the salt bath, and air-cooling.
3) Cleaning and drying; cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The detection proves that the nitriding layer depth of the 420J2 stainless steel suture needle is 13 +/-3 mu m, and the surface hardness is HV620 +/-30.
Example 4
Annealing the 420J2 stainless steel wire to HV250, pre-processing, and adopting the salt bath formula of the following low-temperature salt bath nitriding formula, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,27％
Na2CO3，15％
K2CO3，15％
Li2CO3，8％
Na2SO3，6％
KCl，15％
CeCO3，3％
Y2(CO3)3，3％
Sr(OH)2，8％
the 420J2 martensitic stainless steel is subjected to salt bath nitriding treatment by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly and heated to 450 ℃ for heat preservation so that the components in the salt bath are completely melted.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at 480 ℃, nitriding for 60min, taking out after the salt bath, and air-cooling.
3) Cleaning and drying; cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The detection proves that the depth of the nitriding layer of the 420J2 stainless steel suture needle is 17 +/-3 mu m, and the surface hardness is HV640 +/-30.
Example 5
The annealing hardness of the 420J2 stainless steel wire is HV270, and after pre-processing, the salt bath formula of the following low-temperature salt bath nitriding formula is adopted, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,15％
Na2CO3，12％
K2CO3，27％
Li2CO3，10％
Na2SO3，10％
KCl，10％
CeCO3，4％
Y2(CO3)3，4％
Sr(OH)2，8％
the 420J2 martensitic stainless steel is subjected to salt bath nitriding treatment by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly and heated to 450 ℃ for heat preservation so that the components in the salt bath are completely melted.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at 490 ℃, nitriding for 50min, taking out after the salt bath, and air-cooling.
3) Cleaning and drying; cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The 420J2 stainless steel suture needle is detected to have the nitriding layer depth of 19 +/-3 mu m and the surface hardness of HV670 +/-30.
Example 6
The annealing hardness of the 420J2 stainless steel wire is HV260, and after pre-processing, the salt bath formula of the following low-temperature salt bath nitriding formula is adopted, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,25％
Na2CO3，20％
K2CO3，26％
Li2CO3，8％
Na2SO3，8％
KCl，5％
CeCO3，2％
Y2(CO3)3，2％
Sr(OH)2，4％
the 420J2 martensitic stainless steel is subjected to salt bath nitriding treatment by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly and heated to 450 ℃ for heat preservation so that the components in the salt bath are completely melted.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at the treatment temperature of 500 ℃ for 20min, taking out the suture needle after the salt bath, and performing air cooling.
3) Cleaning and drying; cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The 420J2 stainless steel suture needle was tested to have a nitriding layer depth of 13 + -2 μm and a surface hardness of HV650 + -20.
Example 7
The annealing hardness of the 420J2 stainless steel wire is HV280, and after pre-processing, the salt bath formula of the following low-temperature salt bath nitriding formula is adopted, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,30％
Na2CO3，20％
K2CO3，22％
Li2CO3，5％
Na2SO3，2％
KCl，5％
CeCO3，4％
Y2(CO3)3，4％
Sr(OH)2，8％
the 420J2 martensitic stainless steel is subjected to salt bath nitriding treatment by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly and heated to 450 ℃ for heat preservation so that the components in the salt bath are completely melted.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at the treatment temperature of 500 ℃ for 60min, taking out the suture needle after the salt bath, and performing air cooling.
3) Cleaning and drying; cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The 420J2 stainless steel suture needle is detected to have a nitriding layer depth of 21 +/-3 mu m and a surface hardness of HV670 +/-30.
Example 8
The annealing hardness of the 420J2 stainless steel wire is HV280, and after pre-processing, the salt bath formula of the following low-temperature salt bath nitriding formula is adopted, wherein the salt bath formula comprises the following components in percentage by weight:
CO(NH2)2,25％
Na2CO3，15％
K2CO3，25％
Li2CO3，7％
Na2SO3，6％
KCl，10％
CeCO3，3％
Y2(CO3)3，3％
Sr(OH)2，6％
the 420J2 martensitic stainless steel is subjected to salt bath nitriding treatment by adopting the salt bath formula, and the salt bath nitriding treatment comprises the following steps:
1) the components are stirred evenly and heated to 450 ℃ for heat preservation so that the components in the salt bath are completely melted.
2) And (3) performing salt bath treatment on the martensitic stainless steel suture needle at the treatment temperature of 500 ℃ for 60min, taking out the suture needle after the salt bath, and performing air cooling.
3) Cleaning and drying; cleaning the stainless steel suture needle treated in the step 2) with water and then drying.
The detection proves that the nitriding layer depth of the 420J2 stainless steel suture needle is 23 +/-2 mu m, and the surface hardness is HV680 +/-20.
Claims (3)
1. The salt bath formula for low-temperature salt bath nitridation of martensitic stainless steel is characterized in that the components of the salt bath formula comprise CO (NH)2)2、Na2CO3、K2CO3、Li2CO3、K2SO3、KCl、CeCO3、Y2(CO3)3And Sr (OH)2。
2. The salt bath formulation of claim 1, wherein the salt bath formulation comprises the following components in percentage by weight:
CO(NH2)2：15％-30％
Na2CO3：10-20％
K2CO3：15-30％
Li2CO3：5-10％
Na2SO3：2-10％
KCl：5-15％
CeCO3：2-4％
Y2(CO3)3：2-4％
Sr(OH)2：4-8％。
3. a processing method of a martensitic stainless steel medical suture needle is characterized by comprising the following steps:
the method comprises the following steps:
cold-drawing the martensitic stainless steel wire to the required specifications with different diameters, annealing the martensitic stainless steel wire until the hardness is less than or equal to HV280, and uncoiling, straightening, cutting, processing a needle hole, processing a needle point and bending the martensitic stainless steel wire to realize the processing and forming of the medical suture needle;
step two:
heating and quenching the martensitic stainless steel suture needle;
step three:
1) salt bath nitriding: the salt bath formula of the low-temperature salt bath nitriding according to any one of claims 1-2 is adopted, so that all components are uniformly stirred, heated to 450 ℃, and the temperature is kept to completely melt all the components of the salt bath; performing salt bath treatment on the martensitic stainless steel suture needle, wherein the treatment temperature is between 450 ℃ and 500 ℃, the nitriding time is 20-60min according to the diameter size of the suture needle, and taking out the suture needle after the salt bath for air cooling;
2) cleaning and drying; cleaning the stainless steel suture needle treated in the step 1) with water and then drying.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2020115807108 | 2020-12-28 | ||
| CN202011580710 | 2020-12-28 |
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| CN115558884A (en) * | 2022-10-21 | 2023-01-03 | 上海交通大学 | Heat treatment method for eliminating quenching residual stress of super martensitic stainless steel and improving surface hardness |
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| CN115558884A (en) * | 2022-10-21 | 2023-01-03 | 上海交通大学 | Heat treatment method for eliminating quenching residual stress of super martensitic stainless steel and improving surface hardness |
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