阅读说明：本技术 一种用于记忆合金管接头的坯料及制备方法 (Blank for memory alloy pipe joint and preparation method ) 是由 宋晓云 李艳锋 刘睿 于洋 骆雨萌 罗峥 叶文君 惠松骁 于 2020-11-19 设计创作，主要内容包括：本发明公开了一种用于记忆合金管接头的坯料,相对于总量100重量％,所述坯料包含4重量％至6重量％的Fe、40重量％至44重量％的Ti、小于0.005重量％的H、小于0.1重量％的O、0.001重量％至0.05重量％的C、小于0.005重量％的N、余量为Ni以及不可避免的杂质,铸锭采用真空感应熔炼与真空自耗熔炼复合熔炼的方法,在保证成分均匀性的同时获得大规格铸锭,制备铸锭重量不低于300kg,采用热加工方式制备棒坯后进行冷轧,冷变形量10％～20％,相较于所述记忆合金的整体显微组织100体积％,坯料具有大于或等于97体积％的再结晶组织。(The invention discloses a blank for a memory alloy pipe joint, which comprises 4-6 wt% of Fe, 40-44 wt% of Ti, less than 0.005 wt% of H, less than 0.1 wt% of O, 0.001-0.05 wt% of C, less than 0.005 wt% of N, the balance of Ni and inevitable impurities relative to 100 wt% of the total amount, wherein the ingot is prepared by a method of vacuum induction melting and vacuum consumable melting composite melting, a large-size ingot is obtained while the component uniformity is ensured, the weight of the prepared ingot is not less than 300kg, a bar blank is prepared by a hot processing mode and then is subjected to cold rolling, the cold deformation amount is 10-20%, and compared with the 100 vol% of the integral microstructure of a memory alloy, the blank has a recrystallization structure of more than or equal to 97 vol%.)

1. A blank for a memory alloy pipe joint, comprising: the blank comprises 4-6 wt% of Fe, 40-44 wt% of Ti, less than 0.005 wt% of H, less than 0.1 wt% of O, 0.001-0.05 wt% of C, less than 0.005 wt% of N, the balance of Ni and inevitable impurities relative to 100 wt% of the total amount, the ingot is prepared by a method of composite smelting of vacuum induction smelting and vacuum consumable smelting, a large-size ingot is obtained while the uniformity of components is ensured, the weight of the ingot is not less than 300kg, a cold rolling is carried out after a bar blank is prepared by a hot working mode, the cold deformation amount is 15-25%, and compared with 100 vol% of the whole microstructure of the memory alloy, the blank has a recrystallization structure which is greater than or equal to 97 vol%.

2. A blank for a memory alloy tube fitting as claimed in claim 1 wherein: the blank has an average grain size of 10 to 20 μm.

3. A blank for a memory alloy tube fitting as claimed in claim 1 wherein: the volume ratio of martensite in the blank is less than 5%.

4. A blank for a memory alloy tube fitting as claimed in claim 1 wherein: the billet contains 0.02 wt% C.

5. A blank for a memory alloy tube fitting as claimed in claim 1 wherein: the billet comprises 5.5 wt% Fe; the blank contains 42 wt% Ti.

6. A method for manufacturing a blank for a memory alloy pipe joint according to any one of claims 1 to 5, wherein: which comprises the following steps:

(1) high-purity Ti, high-purity Ni, high-purity Fe and trace carbon are used as raw materials, accurately weighed and proportioned;

(2) mixing the prepared alloy raw materials, and then adopting a mode of combining vacuum induction melting and vacuum consumable melting for melting, specifically, firstly carrying out vacuum induction melting for 1-3 times, and then carrying out vacuum consumable melting for 1-3 times to obtain a large-size alloy ingot, so as to ensure the uniformity of components;

(3) casting ingot cogging: hot-pressing and cogging the cast ingot at 950-1050 ℃, controlling the remelting of elements by adopting a slow strain rate to ensure the uniformity of the structure, and controlling the initial strain rate to be 1 multiplied by 10^-4～3×10^-4s^-1；

(4) Preparing a bar blank: preparing a bar blank by adopting a cooling forging mode, wherein the forging temperature is 820-920 ℃, the heat deformation is 40-60%, and the final forging size is 15-30 mm;

(5) cold rolling: and (3) performing cold rolling deformation on the bar blank, applying certain cold deformation to improve the strength, and preparing the blank for the pipe joint, wherein the cold deformation of the blank is 10-20%.

7. A method of manufacturing a blank for a memory alloy pipe joint according to claim 6, wherein: after mixing the prepared alloy raw materials, adopting a mode of combining vacuum induction melting and vacuum consumable melting for melting, specifically, firstly carrying out vacuum induction melting for 2 times, and then carrying out vacuum consumable melting for 3 times to obtain a large-size alloy ingot, thereby ensuring the uniformity of components.

8. A method of manufacturing a blank for a memory alloy pipe joint according to claim 6, wherein: hot pressing the cast ingot at 1000 deg.CCogging, using slow strain rate to control the melt back of the elements to ensure the uniformity of the structure, and controlling the initial strain rate to be 2 x 10^-4s^-1。

9. A method of manufacturing a blank for a memory alloy pipe joint according to claim 6, wherein: the bar billet is prepared by adopting a cooling forging mode, wherein the forging temperature is 870 ℃, the heat deformation is 50%, and the final forging size is 20 mm.

10. A method of manufacturing a blank for a memory alloy pipe joint according to claim 6, wherein: and (3) carrying out cold rolling deformation on the bar blank, applying certain cold deformation to improve the strength, and preparing the blank for the pipe joint, wherein the cold deformation of the blank is 15%.

Technical Field

The invention belongs to the field of alloy blank preparation, and particularly relates to a blank for a memory alloy pipe joint and a preparation method thereof.

Background

The TiNiFe alloy is a shape memory alloy material with low phase-transition temperature, has excellent comprehensive performance and is commonly used for preparing pipe joints for aviation hydraulic pipelines. At present, the memory alloy pipe joint is widely applied to the sealing connection of various gas circuits and oil circuits in the fields of spaceflight and aviation.

CN1614056A of Beijing aerospace university discloses a low-phase-change point TiNiFe shape memory alloy and application thereof as a pipe joint, wherein the low-phase-change point TiNiFe shape memory alloy comprises the components and the contents of 0.1-5 percent of iron (Fe), 46-50 percent of titanium (Ti) and 46-50 percent of nickel (Ni). The pipe joint is made of TiNiFe shape memory alloy material through smelting and forging into bar material and machining into required structure and shape. The pipe joint can be used for reaming at the low temperature of between room temperature and 196 ℃ below zero to be connected with each pipe fitting, and when the temperature naturally returns to the room temperature, the pipe joint tightly holds the pipe fittings to achieve the purpose of no leakage. The shape memory alloy pipe joint has the advantages of light weight, high bearing pressure and good safety and reliability.

An electrode material for TiNiFe alloy vacuum consumable melting and a preparation thereof, which belong to the technical field of plate electrode materials, are also disclosed in CN109355511A by research engineering technology research institute Co. The electrode material comprises more than two sections of electrode plates, the adjacent two sections of electrode plates are spliced in a high-low dislocation mode, each section of electrode plate comprises the same number of electrode plate material units, and the electrode plate material units are high-purity titanium plate-high-purity iron plate-high-purity nickel plate composite plates with a sandwich structure; the splicing mode of the plate electrode material units in the adjacent two sections of electrode plates is that a high-purity titanium plate, a high-purity iron plate and a high-purity nickel plate are spliced in an aligned mode with a high-purity nickel plate, a high-purity iron plate and a high-purity titanium plate. The provided electrode material for TiNiFe alloy vacuum consumable melting has accurate component proportioning and high welding connection strength, and lays a foundation for TiNiFe alloy with uniform vacuum induction melting components and low impurity content; the preparation method is simple, and can be popularized to the preparation of plate electrode materials of other titanium alloys by vacuum consumable melting.

However, the existing research on the TiNiFe alloy is still few, and more progress spaces exist in the aspects of component regulation and performance optimization. The phase transition temperature and the recovery stress of the TiNiFe alloy are very sensitive to the uniformity of the main element composition of the alloy and the content of impurity elements. At present, the common TiNiFe memory alloy is usually prepared into an ingot by adopting a vacuum induction melting mode and is processed into a bar billet by heating, and the problem that (1) because Fe element is easy to segregate, the weight of the ingot is small and generally does not exceed 50kg in order to control the uniformity of components; (2) in order to meet the application, a plurality of ingots are usually required to be smelted, so that the stability of batches among different ingots is poor, and the performance difference of the processed pipe joints is large; (3) the strength of the hot-processed bar blank is low, so that the recovery stress is low, and the fastening effect of the alloy prepared pipe joint is further influenced. How to obtain a high-performance blank capable of being used for a memory alloy pipe joint and a preparation method thereof by optimizing raw materials and a preparation process thereof is a problem to be solved urgently.

Disclosure of Invention

The invention aims to solve the problems and develop a blank for a memory alloy pipe joint and a preparation method thereof:

a blank for a memory alloy pipe joint, comprising: the blank comprises 4-6 wt% of Fe, 40-44 wt% of Ti, less than 0.005 wt% of H, less than 0.1 wt% of O, 0.001-0.05 wt% of C, less than 0.005 wt% of N, the balance of Ni and inevitable impurities relative to 100 wt% of the total amount, the ingot is prepared by a method of composite smelting of vacuum induction smelting and vacuum self-consumption smelting, a large-size ingot is obtained while the uniformity of components is ensured, the weight of the ingot is not less than 300kg, a cold rolling is carried out after a bar blank is prepared by a hot processing mode, the cold deformation amount is 10-20%, and compared with 100 vol% of the whole microstructure of the memory alloy, the blank has a recrystallization structure which is greater than or equal to 97 vol%.

Preferably, the billet may have an average grain size of 10 to 20 μm.

Preferably, the volume proportion of martensite in the blank is less than 5%;

preferably, the billet comprises 0.001 to 0.05 wt% C, more preferably 0.02 wt% C;

preferably, the billet comprises 4 to 6 wt% Fe, more preferably 5.5 wt% Fe;

preferably, the blank comprises 40 to 44 wt% Ti, more preferably 42 wt% Ti;

a preparation method of a blank for a memory alloy pipe joint comprises the following steps:

(1) high-purity Ti, high-purity Ni, high-purity Fe and trace carbon are used as raw materials, accurately weighed and proportioned;

(2) mixing the prepared alloy raw materials, and then adopting a mode of combining vacuum induction melting and vacuum consumable melting for melting, specifically, firstly carrying out vacuum induction melting for 1-3 times, and then carrying out vacuum consumable melting for 1-3 times to obtain a large-size alloy ingot, so as to ensure the uniformity of components;

(3) casting ingot cogging: hot-pressing and cogging the cast ingot at 950-1050 ℃, controlling the remelting of elements by adopting a slow strain rate to ensure the uniformity of the structure, and controlling the initial strain rate to be 1 multiplied by 10^-4～3×10^-4s^-1；

(4) Preparing a bar blank: preparing a bar blank by adopting a cooling forging mode, wherein the forging temperature is 820-920 ℃, the heat deformation is 40-60%, and the final forging size is 15-30 mm;

(5) cold rolling: and (3) cold rolling the bar blank, and applying certain cold deformation to improve the strength to prepare the blank for the pipe joint, wherein the cold deformation of the blank is 10-20%.

Preferably, the prepared alloy raw materials are mixed and then melted by combining vacuum induction melting and vacuum consumable melting, specifically, the vacuum induction melting is performed for 2 times at first, and then the vacuum consumable melting is performed for 3 times, so that a large-size alloy ingot is obtained, and the uniformity of components is ensured.

Preferably, the ingot is hot pressed at 1000 ℃Cogging, using slow strain rate to control the melt back of the elements to ensure the uniformity of the structure, and controlling the initial strain rate to be 2 x 10^-4s^-1。

Preferably, the bar blank is prepared by adopting a cooling forging mode, wherein the forging temperature is 870 ℃, the heat deformation is 50%, and the final forging size is 20 mm.

Preferably, the bar stock is cold-rolled to increase the strength by applying a certain cold deformation, and a pipe joint stock is prepared, the cold deformation amount of the stock being 15%.

In the present specification, the grain size refers to the diameter of the crystal grain present in the measurement unit. If the crystal grains are non-spherical, the crystal grain diameter refers to a diameter calculated as the diameter of an approximate sphere of the non-spherical crystal grains.

The reason for limiting the composition and the range of the components of the alloy in the present invention will be explained below.

The carbon (C) may be contained in 0.001 to 0.05 wt%. Specifically, when trace carbon is added, heterogeneous nucleation can be generated in the alloy, the crystal orientation is subjected to morphological change in the solid-liquid change process, the peritectic reaction process is facilitated, but the ceramic phase TiC can be generated due to the fact that the content of C is too large, precipitation of a second phase is strengthened, the compressive yield strength of the blank is affected, and the recovery stress of the alloy is affected. The billet contains 0.001 to 0.05 wt% of C, more preferably 0.02 wt% of C

The iron (Fe) may comprise 4 to 6 wt%. When a certain amount of iron is added, the grain size of the blank is increased, the average diameter of grains is reduced, the strength of the blank can be improved, and the solid solution strengthening of a system can be improved. The blank comprises 4 to 6 wt% Fe, more preferably 5.5 wt% Fe.

Less than 0.005 wt% H, less than 0.005 wt% O, less than 0.005 wt% N; this avoids excessive formation of secondary phases and affects the back-melting of the elements.

The blank and the preparation method thereof have the following technical effects:

the composition of the NiTiFe alloy is optimized, so that the prepared blank for the memory alloy pipe joint has high yield strength and thermal conductivity; because Fe element is easy to segregate and the uniformity of components is difficult to control by directly adopting vacuum consumable melting, the prepared alloy raw materials are mixed and then are melted by adopting a combined melting mode of vacuum induction melting and consumable melting to obtain large-size alloy ingots and ensure the uniformity of the components; the method comprises the steps of controlling the remelting of elements by adopting a slow strain rate through a special hot-pressing cogging process to ensure that the structure is uniform, preparing a bar blank by adopting hot working, and then carrying out cold rolling to prepare a blank for the pipe joint, wherein the cold deformation of the blank is 10-20%, so that the blank has excellent yield strength and recovery stress thermal conductivity.

Detailed Description

The present invention is described in further detail below with reference to specific examples and with reference to the data. It will be understood that these examples are intended to illustrate the invention and are not intended to limit the scope of the invention in any way.

Example 1:

a preparation method of a blank for a memory alloy pipe joint comprises the following steps:

(1) high-purity Ti, high-purity Ni, high-purity Fe and trace carbon are used as raw materials, accurately weighed and proportioned;

(2) mixing the prepared alloy raw materials, and then adopting a mode of combining vacuum induction melting and vacuum consumable melting for melting, specifically, firstly carrying out vacuum induction melting for 2 times, and then carrying out vacuum consumable melting for 3 times to obtain a large-size alloy ingot, so as to ensure the uniformity of components;

(3) casting ingot cogging: hot-pressing and cogging the cast ingot at 1000 ℃, controlling the remelting of elements by adopting a slow strain rate to ensure the uniformity of the structure, and controlling the initial strain rate to be 2 x 10 < -4 > s < -1 >;

(4) preparing a bar blank: preparing a bar blank by adopting a cooling forging mode, wherein the forging temperature is 870 ℃, the heat deformation is 50%, and the final forging size is 20 mm;

(5) cold rolling: and (3) cold rolling the bar blank, applying certain cold deformation to improve the strength, and preparing the blank for the pipe joint, wherein the cold deformation of the blank is 15%.

A blank for a memory alloy pipe joint comprises 5.5 wt% of Fe, 42 wt% of Ti, 0.02 wt% of C, 0.001 wt% of H, 0.001 wt% of O, 0.001 wt% of N and the balance of Ni and inevitable impurities relative to 100 wt% of the total amount, the ingot is subjected to a composite smelting method of vacuum induction smelting and vacuum consumable melting, a large-size ingot is obtained while the uniformity of components is ensured, the weight of the prepared ingot is 350kg, a bar blank is prepared in a hot processing mode and then is subjected to cold rolling, the cold deformation amount is 15%, and compared with the 100 vol% of the overall microstructure of the memory alloy, the blank has a recrystallization structure which is greater than or equal to 97 vol%. The blank had an average grain size of 15 μm. The volume ratio of martensite in the blank is less than 5%.

Example 2-example 27:

examples 2 to 27 are based on example 1, and are different from example 1 in the content of each element of the green body and the preparation process, and specific differences are shown in table 1, and table 1 also includes yield strength, recovery stress thermal conductivity and surface hardness data corresponding to each example.

Comparative example 1 to comparative example 23:

comparative examples 1 to 23 are based on example 1, and are different from example 1 in the content of each element of the green body and the preparation process, and are used for comparing the influence of relevant factors on yield strength, recovery stress thermal conductivity and surface hardness data.

TABLE 1

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.