CN114703403B - CoCrMo alloy, its preparation method and its use - Google Patents

Abstract

The invention provides a CoCrMo alloy, a preparation method and application thereof, and belongs to the technical field of alloy preparation. The alloy comprises the following components in percentage by mass: c:0.10 to 0.35%, cr:26.5 to 30.0%, mo:4.5 to 7.0%, ni:0.5 to 1.0%, fe:0.5 to 1.0%, mn:0.5 to 1.0%, si:0.5 to 1.0%, N: 0.1-0.2% and Co as the rest. The preparation method of the alloy casting comprises the following steps: obtaining alloy elements and intermediate alloy according to the mass percentage of each component; after the alloy elements and the intermediate alloy are smelted, obtaining a master alloy ingot to be poured; and (3) carrying out casting molding and post-treatment on the mother alloy ingot to be poured to obtain the artificial implant casting of the CoCrMo alloy. The casting body has good tensile strength, yield strength and elongation at room temperature, is stable, and can meet the requirement of batch production of CoCrMo alloy artificial implants.

Description

CoCrMo alloy, its preparation method and its use

technical field

The invention relates to the technical field of alloy preparation, in particular to CoCrMo alloy, its preparation method and its application.

Background technique

CoCrMo alloy casting artificial implants are generally used in cast state, hot isostatic pressing state, or solid solution state after production. The result of these three states is that the single-cast test bar representing the mechanical properties is easy to pass, but the mechanical properties of the artificial implant casting body, including room temperature tensile strength, yield strength and elongation, are often unqualified, which has long troubled the production plant. , It often happens that the entire batch of castings are scrapped due to unqualified mechanical properties, the production cost is greatly increased, or the service life of the product is reduced, so it can only be downgraded for use.

Compared with stainless steel and titanium alloy, CoCrMo alloy has good tensile properties, corrosion resistance and good biocompatibility with human body. It has become the most ideal material for artificial implants in clinical practice and is widely used in metal Surgical implants such as hip and knee joints. In the production process, the mechanical properties of CoCrMo alloy test rods are easy to meet the standards, but the room temperature tensile strength, yield strength and elongation of the mechanical properties of the cast artificial implant castings produced by it are often unqualified, which has troubled producers for a long time. A whole batch of castings were scrapped due to unqualified tensile properties at room temperature, and the production cost increased significantly. The microstructure of the CoCrMo alloy is composed of a cobalt-based face-centered cubic matrix phase and a carbide phase. The present invention mainly changes the composition of the CoCrMo alloy, increases and optimizes the hot isostatic pressing and heat treatment system of the casting, thereby changing the microstructure of the casting and improving the tensile strength of the alloy at room temperature. Tensile strength, yield strength and elongation, while reducing property fluctuations, thus ensuring room temperature tensile properties.

Contents of the invention

In view of this, the present invention provides a kind of CoCrMo alloy, its preparation method and application thereof, and the casting body sampling room temperature tensile strength, yield strength, elongation of the CoCrMo alloy obtained by adopting this CoCrMo alloy and casting preparation method are good, and stable , which can meet the needs of mass production of CoCrMo alloy artificial implant castings.

In order to achieve the above-mentioned first object, the technical scheme of the CoCrMo alloy provided by the present invention is as follows:

The mass percent content of each component of the CoCrMo alloy provided by the present invention includes: C: 0.10-0.35%, Cr: 26.5-30.0%, Mo: 4.5-7.0%, Ni: 0.5-1.0%, Fe: 0.5-1.0% , Mn: 0.5-1.0%, Si: 0.5-1.0%, N: 0.1-0.2%, and Co is the balance.

In order to achieve the above-mentioned second purpose, the technical scheme of the preparation method of the CoCrMo alloy provided by the invention is as follows:

The preparation method of the casting of CoCrMo alloy provided by the present invention is characterized in that, comprises the following steps:

According to the mass percentage of each component, it includes: C: 0.10～0.35%, Cr: 26.5～30.0%, Mo: 4.5～7.0%, Ni: 0.5～1.0%, Fe: 0.5～1.0%, Mn: 0.5～ 1.0%, Si: 0.5-1.0%, N: 0.1-0.2%, Co is the balance to obtain alloy elements, among which, N is obtained in the form of CrN master alloy;

After the alloying elements and the master alloy are smelted, a master alloy ingot to be poured is obtained;

The ingot of the master alloy to be casted is cast and post-treated to obtain the artificial implant casting of the CoCrMo alloy.

The preparation method of the CoCrMo alloy provided by the present invention can also be further realized by adopting the following technical measures.

Preferably, after the alloying elements and the master alloy are smelted, obtaining the master alloy ingot to be poured comprises the following steps:

The C, Cr, Mo, Ni, Fe, Mn, Si, Co are melted to obtain the melted first alloy liquid;

The melted first alloy liquid is refined to obtain a fully alloyed first alloy liquid;

The conjunctiva of the fully alloyed first alloy solution is obtained to obtain the first alloy solution after the conjunctiva;

Adding a CrN intermediate alloy to the first alloy liquid behind the conjunctiva and heating and melting to obtain a second alloy melt;

The temperature of the second alloy melt is lowered to the pouring temperature and poured into an ingot mold to make a master alloy ingot.

Preferably, the casting of the master alloy ingot to be poured comprises the following steps:

Preparation of cast shell molds;

According to the weight required for the target configuration of the CoCrMo alloy, cut out a master alloy ingot corresponding to the weight required for the target configuration;

A master alloy ingot corresponding to the weight required by the target configuration is poured into the casting shell in a molten state to obtain a shaped casting.

Preferably, the post-treatment of the master alloy ingot to be cast includes the following steps:

After the formed casting is subjected to hot isostatic pressing, pretreatment, solution treatment and aging treatment in sequence, the casting of the CoCrMo alloy is obtained.

As a preference,

During the step of refining the melted first alloy liquid to obtain a fully alloyed first alloy liquid, the refining duration ranges from 40 to 60 minutes;

Adding a CrN intermediate alloy to the first alloy liquid after the conjunctiva and heating and melting to obtain the second alloy melt, the melting duration ranges from 3 to 5 minutes;

The temperature of the second alloy melt is lowered to the pouring temperature and then poured into the ingot mold to form a master alloy ingot. The pouring temperature ranges from 1550°C to 1600°C.

Preferably, the step of preparing the cast shell mold comprises the following steps:

Pressing the wax mold to obtain the wax mold of the casting of the CoCrMo alloy to be formed and the wax mold of the gating system, combining the wax mold of the casting and the wax mold of the gating system to obtain the wax mold assembly of the casting of the CoCrMo alloy;

Circulating the set number of times on the surface of the casting wax pattern component of the CoCrMo alloy to coat the silica sol slurry, sand shower, and dry to obtain the first intermediate product;

The first intermediate product is removed from the wax mold in the dewaxing kettle under steam conditions with a temperature range of 150-200° C. and a pressure range of 5-7 MPa to obtain a second intermediate product;

The second intermediate product is calcined at 700-900° C. for 2-4 hours to obtain the casting shell.

Preferably, the master alloy ingot corresponding to the weight required by the target configuration is poured into the cast shell mold in a molten state, and during the step of obtaining a shaped casting:

The preheating temperature range of the casting shell mold before pouring is 1000-1100°C;

The temperature range of the master alloy ingot corresponding to the weight required by the target configuration in a molten state is 1550-1600°C;

During the pouring molding process, the value range of the ambient pressure is within 1Pa.

As a preference, after the formed casting is subjected to hot isostatic pressing, pretreatment, solution treatment and aging treatment in sequence, during the step of obtaining the casting of the CoCrMo alloy, the processing conditions include:

Hot isostatic pressing: the temperature range is 1200-1250°C, the holding time range is 2-5h, the pressure range is 140-180MPa, and then cooled to room temperature;

Pretreatment: The temperature range is 700-900°C, the holding time range is 2-5h, and then air-cooled to room temperature;

Solution treatment: the temperature range is 1210-1250°C, the holding time ranges from 2-5h, and then quickly immersed in the salt solution to cool to room temperature;

Aging treatment: The temperature range is 500-700°C, the holding time ranges from 2-6h, and then air-cooled to room temperature.

In order to achieve the above-mentioned third purpose, the technical scheme of the purposes of the casting of CoCrMo alloy provided by the present invention is as follows:

The casting of the CoCrMo alloy provided by the invention is used for improving the sampling mechanical properties of the artificial implant body.

Compared with the traditional CoCrMo alloy casting, the present invention has significant advantages. It stabilizes the fine content of Ni, Fe, Mn and Si elements and strengthens the matrix phase of fcc, which improves the matrix strength; In the fcc phase region, the yield strength at room temperature is greatly improved; the cooling rate is further accelerated by salt bath cooling after solid solution treatment, and a supersaturated solid solution is obtained to ensure that the plasticity is improved while the strength remains unchanged; by increasing the aging treatment and controlling the aging temperature, the alloy is improved. Strength without strengthening phase aggregation and softening, which further stabilizes other performance indicators at room temperature; by matching appropriate hot isostatic pressing and heat treatment systems and different cooling methods, a dense internal structure and stable microstructure are obtained. While the mechanical properties of casting body samples are improved, the performance dispersion is smaller. The internal compactness of the casting obtained by the present invention can be as follows: as shown in Figure 2, under the 100 times field of view, the internal microporosity observed by an optical microscope is less than 0.1%; as shown in Figure 3, the microstructure is composed of austenite solid solution and carbonization The carbide is distributed in the grain boundary and between the dendrites in the form of a skeleton. The element control and heat treatment system of the present invention makes the carbide with a high microhardness of 970HV (Vickers hardness) more uniformly embedded in the austenite with a low hardness of 465HV , so that the mechanical properties are higher and more stable.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating a preferred embodiment and are not to be considered as limiting the invention. Also throughout the drawings, the same reference numerals are used to designate the same parts. In the attached picture:

Fig. 1 adopts the CoCrMo alloy casting of the present invention to prepare and the schematic diagram of sampling of mechanical property body;

Fig. 2 is the microstructural diagram of the CoCrMo alloy casting that adopts the inventive method to prepare;

Fig. 3 is a microstructure diagram of a CoCrMo alloy casting prepared by a comparative method.

Detailed ways

In view of this, the present invention provides a kind of CoCrMo alloy, its preparation method and application thereof, and the casting body sampling room temperature tensile strength, yield strength, elongation of the CoCrMo alloy obtained by adopting this CoCrMo alloy and casting preparation method are good, and stable , which can meet the needs of mass production of CoCrMo alloy artificial implant castings.

In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation of a CoCrMo alloy proposed according to the present invention, its preparation method and its use will be described below in conjunction with the accompanying drawings and preferred embodiments. Mode, structure, feature and effect thereof are as follows in detail. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

The term "and/or" in this article is just an association relationship describing associated objects, which means that there can be three relationships, for example, A and/or B. The specific understanding is: A and B can be included at the same time, and A and B can be included separately. A exists, B may exist alone, and any of the above three situations can be met.

The mass percent of the chemical composition of the alloy involved in the present invention is: C 0.10-0.35%, Cr 26.5-30.0%, Mo 4.5-7.0%, Ni 0.5-1.0%, Fe 0.5-1.0%, Mn 0.5-1.0%, Si 0.5% ～1.0%, N 0.1～0.2%, Co as the balance. The casting preparation steps are as follows:

Batching is carried out according to the chemical composition ratio of the alloy, and it is put into a vacuum induction melting furnace for smelting. The smelting process includes five steps of melting, refining, alloying, cooling and pouring; before melting, C, Cr, Mo, Ni, Fe, Mn, Si, Co are loaded into the crucible, after melting, refining for 40-60 minutes, after refining, stir the alloy liquid melt, wait until it is fully alloyed, then turn off the power and cool down until the alloy liquid conjunctiva; turn on the power again, add CrN and After smelting for 3-5 minutes, stir the alloy liquid melt to homogenize the composition; finally, cut off the power to cool down, and pour when the temperature of the alloy liquid melt reaches the pouring temperature. The pouring temperature is 1550-1600°C. Liquid melt, pouring alloy liquid melt into an ingot mold to make a master alloy ingot;

Use the wax mold to press out the artificial implant casting wax mold, and then combine multiple casting wax molds into a wax mold module, and cycle 6-8 times on the surface of the wax mold module to coat the silica sol slurry, sand, and dry , and then use high-temperature and high-pressure water vapor with a temperature of 150-200 °C and a pressure of 5-7 MPa in a dewaxing kettle to remove the wax mold, and prepare a cast shell mold after roasting at 700-900 °C for 2-4 hours;

Put the cast shell mold prepared above into a roasting furnace for preheating, set the preheating temperature at 1000-1100°C; cut out the master alloy ingot according to the weight required for casting artificial implant castings, and put the master alloy ingot into vacuum induction melting In the furnace crucible, heat to 1550-1600°C to melt the master alloy ingot, quickly transfer the casting shell mold from the roasting furnace to the vacuum induction melting furnace, evacuate to within 1Pa, and then pour the molten metal into the casting shell mold, Take out the casting after cooling;

The obtained casting is subjected to hot isostatic pressing+pretreatment+solution treatment+aging treatment. The system adopted is: (1) hot isostatic pressing: heat preservation at a temperature of 1200-1250 °C and a pressure of 140-180 MPa for 2 to 5 hours, and then cool to room temperature in the furnace; (2) pretreatment: heat preservation at 700-900 °C for 2 ~5h, then air-cooled to room temperature; (3) Solid solution treatment: keep warm at 1210-1250°C for 2-5h, then quickly immerse in salt solution and cool to room temperature; (4) Aging treatment: keep warm at 500-700°C for 2-5h 6h, then cooled to room temperature in air.

Samples for tensile mechanical properties at room temperature were cut from the heat-treated artificial joint implant casting body for testing.

Example 1-5

The alloy chemical composition mass percent of table 1 embodiment 1-5

The operating parameter of table 2-1 embodiment 1-5

The operating parameter of table 2-2 embodiment 1-5

Comparative example 1-5

Preparation method of comparative example 1-5 alloy: melting C, Cr, Mo, Co to obtain molten alloy liquid; refining the molten alloy liquid, lowering the temperature to pouring temperature and pouring it into an ingot mold to make a master alloy Ingot, the operating parameters during the preparation process are shown in Table 4-1 and Table 4-2. The difference from the present invention is that Ni, Fe, Mn, Si, N are not added individually, they exist only as impurities.

Alloy chemical composition mass percentage of comparative example 1-5 of table 3

Table 4-1 Operating parameters of comparative examples 1-5

Table 4-2 Operating parameters of comparative examples 1-5

After the master alloy ingots obtained in Examples 1-5 and Comparative Examples 1-5 of the present invention were cast and post-treated, samples of tensile mechanical properties at room temperature were cut from the body of the artificial joint implant casting for testing. The results are shown in Table 5.

Table 5 Mechanical properties of casting body samples at room temperature

This shows that the difference between comparative example and embodiment is:

1. Alloying elements in the master alloy ingot, C: ≤0.35%, Ni: ≤1.0%, Fe: ≤1.0%, Mn: ≤1.0%, Si: ≤1.0%, there is no requirement for N element, that is to say, All alloy elements in the comparison ratio are specified with upper limits, which are treated as impurities. There is no requirement for N elements, which are also treated as impurities, which leads to huge differences in elemental alloy composition, poor consistency, violent fluctuations in mechanical properties, and failure to meet the standard requirements.

2. No preprocessing.

3. After solid solution treatment, no salt bath is used for cooling.

4. No aging treatment.

5. The whole process of hot isostatic pressing + heat treatment will not be systematically adopted.

To sum up, the CoCrMo artificial implant casting body obtained by the alloy and casting preparation method of the present invention has excellent sampling mechanical properties, and is suitable for mass production of CoCrMo alloy artificial implant castings.

While preferred embodiments of the invention have been described, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, it is intended that the appended claims be construed to cover the preferred embodiment as well as all changes and modifications which fall within the scope of the invention.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (5)

1. A preparation method of a CoCrMo alloy casting is characterized by comprising the following steps:

the composition comprises the following components in percentage by mass: c:0.20%, cr:27.6%, mo:6.4%, ni:0.7%, fe:0.7%, mn:0.6%, si:0.7%, N:0.15 percent of Co as the balance to obtain alloy elements, wherein N is obtained in a CrN intermediate alloy form;

after the alloy elements and the intermediate alloy are smelted, obtaining a master alloy ingot to be poured;

the master alloy ingot to be poured is subjected to casting molding and post-treatment to obtain an artificial implant casting of the CoCrMo alloy;

the method comprises the following steps of smelting the alloy elements and the intermediate alloy to obtain a master alloy ingot to be poured:

melting the C, cr, mo, ni, fe, mn, si and Co to obtain a molten first alloy liquid;

refining the melted first alloy liquid to obtain fully alloyed first alloy liquid;

the fully alloyed first alloy liquid is formed into a film to obtain a first alloy liquid after the film is formed;

adding a CrN intermediate alloy into the first alloy liquid after film forming, and heating and smelting to obtain a second alloy melt;

cooling the second alloy melt to a pouring temperature, and pouring the second alloy melt into an ingot mold to prepare a master alloy ingot;

the casting molding of the master alloy ingot to be poured comprises the following steps:

preparing a casting shell mold;

cutting a master alloy ingot corresponding to the weight required by the target configuration according to the weight required by the target configuration of the CoCrMo alloy;

casting and molding a master alloy ingot with the weight corresponding to the weight required by the target configuration in the casting shell mold in a molten state to obtain a molded casting;

the step of preparing the cast shell mold comprises the steps of:

pressing by adopting a wax mould to obtain a wax mould of a casting of the CoCrMo alloy to be molded and a wax mould of a pouring system, and combining the casting wax mould and the pouring system wax mould together to obtain a wax mould component of the casting of the CoCrMo alloy;

coating silica sol slurry on the surface of the casting wax mould component of the CoCrMo alloy for a set number of times in a circulating manner, spraying sand, and drying to obtain a first intermediate product;

removing the wax pattern of the first intermediate product in a dewaxing kettle under the conditions of temperature ranging from 150 ℃ to 200 ℃ and pressure ranging from 5 MPa to 7MPa to obtain a second intermediate product;

roasting the second intermediate product at 700-900 ℃ for 2-4h to obtain the casting shell mold;

casting and molding a master alloy ingot with the weight corresponding to the weight required by the target configuration in the casting shell mold in a molten state to obtain a molded casting, wherein the casting comprises the following steps:

the preheating temperature range of the casting shell mold before pouring is 1060 ℃;

the temperature value range of the master alloy ingot corresponding to the weight required by the target configuration in a molten state is 1590 ℃;

in the process of casting molding, the value range of the environmental pressure is within 1 Pa.

2. A method of producing a casting of a CoCrMo alloy according to claim 1, wherein the post-treatment of the master alloy ingot to be poured comprises the steps of:

and sequentially carrying out hot isostatic pressing, pretreatment, solid solution treatment and aging treatment on the formed casting to obtain the CoCrMo alloy casting.

3. A method of making a casting of a CoCrMo alloy as claimed in claim 1,

in the step process of refining the melted first alloy liquid to obtain fully alloyed first alloy liquid, the value range of the refining duration is 50min;

adding a CrN intermediate alloy into the first alloy liquid after film forming, heating and smelting to obtain a second alloy melt, wherein the smelting duration is 3.6min;

and cooling the second alloy melt to a pouring temperature, and pouring the second alloy melt into an ingot mold to prepare a master alloy ingot, wherein the value range of the pouring temperature is 1580 ℃.

4. The method of claim 2, wherein the processing conditions during the step of obtaining the CoCrMo alloy casting are as follows:

hot isostatic pressing: the temperature is 1230 ℃, the temperature holding time is 3h, the pressure is 150MPa, and then the temperature is cooled to room temperature;

pretreatment: the temperature is controlled within 850 ℃, the heat preservation time is controlled within 3h, and then the air cooling is carried out to the room temperature;

solution treatment: the temperature is 1230 ℃, the holding time is 2.5 hours, and then the glass fiber is quickly immersed into a salt solution to be cooled to room temperature;

aging treatment: the temperature is 600 ℃, the holding time is 3h, and then the air cooling is carried out to the room temperature.

5. Use of a casting of a CoCrMo alloy according to any one of claims 1 to 4 for improving the sampling mechanical properties of an artificial implant body.

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