KR20050083601A - Thermomechanical treatment method for fe-mn-si-based shape memory alloy with nb, c addition - Google Patents

Abstract

Means for thermo-mechanical-treatment of an Fe-Mn-Si shape-memory alloy of specified composition doped with NbC comprises performing a mechanical treatment prior to aging treatment at a mechanical treatment ratio falling within a specified range so that the mechanical treatment can be carried out at room temperature, in place of the old method of performing training as a mechanical treatment prior to aging treatment and in place of the prior method of performing a mechanical treatment at 500 to 800°C prior to aging treatment.

Description

Thermomechanical treatment method for Fe-Mn-Si-based shape memory alloy with Nb, C addition}

The present invention relates to a process heat treatment method for a Nb, C-added Fe-Mn-Si-based shape memory alloy. More specifically, the present invention provides a process heat treatment method for Nb and C-added Fe-Mn-Si shape memory alloys that can express the shape memory characteristics of the alloy and improve the characteristics without so-called training. It is about.

Fe-Mn-Si-based shape memory alloys have been proposed and invented for a long time. Unfortunately, the current Fe-Mn-Si-based alloys are not yet fully utilized and have not reached the practical stage. The biggest reason is that this alloy cannot show sufficient shape memory effect without special processing heat treatment called training.

Herein, training means a series of processes in which the following process is repeated several times to improve the shape memory effect. This treatment is to heat the alloy at a temperature of around 600 ° C. which is equal to or greater than the reverse transformation point after the alloy is deformed at a room temperature by 2-3%.

In light of the situation of the related art, which had to require the complicated training process, the inventors of the present application studied intensively to develop a simple operation, especially a machining operation that does not require training. As a result, a small amount of Nb and C elements are added to a specific shape memory alloy, that is, a Fe-Mn-Si-based shape memory alloy, and appropriate aging treatment is performed to precipitate fine NbC carbides in the alloy composition. It was found that exhibiting a sufficiently good shape memory effect without the first and patent application (see Patent Document 1). In addition, the inventors further studied the processing heat treatment means of the Nb, C addition alloy, the Fe-Mn-Si-based shape memory alloy of the Nb, C addition after processing at a temperature range of 500 ~ 800 ℃ Upon aging treatment, it was found that more excellent shape memory characteristics were obtained, and a patent application was also filed for this (see Patent Documents 2 and 3).

Patent document 1;

Japanese Patent Registration Publication No. 3542754

Patent document 2;

Japanese Patent Application No. 2001-296901

Patent document 3;

Japanese Patent Application No. 2002-79295

According to the above proposals, the shape memory alloy technology is remarkably advanced, greatly contributes to the practical use in the future, and contributes greatly to the development of the industry. However, there was still room for further improvement on these proposals themselves. In other words, for the latter two prior patent applications (Patent Document 2, Patent Document 3), the invention by these proposals shows that the processing heat treatment on which the premise is based on the improvement of the shape memory performance of the alloy itself is significantly improved compared to the training. The significance is extremely great because it is easy. Therefore, the degree of practicality improves dramatically. In other words, their actions and effects become extremely remarkable. However, the processing operation for this problem has been a problem in most cases in that the heat treatment at a high temperature in the range of 500 ~ 800 ℃. It is undeniable that such a problem is a factor that impedes the practical use of the shape memory alloy.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the relationship between the shape recovery rate and the initial strain by the heat treatment of the Nb and C-containing Fe-Mn-Si-based shape memory alloy of the present invention;

2 is a view showing the relationship between the shape recovery force and the recovery shape deformation by heat treatment of the Nb, C-added Fe-Mn-Si-based shape memory alloy of the present invention.

It is an object of the present invention to basically solve the above problems.

The inventors of the present invention have discovered and studied stiff shape memory properties that are effective even under low temperature deformation processing for shape memory alloys of a specific composition. As a result, the inventors found that the shape memory characteristic can be sufficiently secured even in the deformation processing at room temperature, and the above-mentioned object can be achieved.

In other words, an alloy having excellent shape memory characteristics can be developed by processing a Fe-Mn-Si shape memory alloy formed by adding Nb and C at room temperature, followed by heat aging treatment to deposit NbC carbides. I found it amazing. That is, the present invention succeeds in achieving the above-mentioned object.

The present invention has been made based on the above findings and successes. Means for solving the above problems are shown in (1) to (7) below.

(1) Deformation processing of a Fe-Mn-Si shape memory alloy formed by adding Nb and C at room temperature at a strain ratio of 5 to 40%, followed by aging and heat treatment of the strain-processed alloy to precipitate NbC carbides. A process heat treatment method for Nb and C-added Fe-Mn-Si shape memory alloys.

(2) Nb, C-added Fe-Mn-Si-based shape memory alloy is an alloy component, Mn: 15 to 40% by weight, Si: 3 to 15% by weight, Nb: 0.1 to 1.5% by weight, C: 0.01 to 0.2 Nb, C-added Fe-Mn-Si-based system according to item (1), wherein the balance is made of Fe and unavoidable impurities, and the atomic ratio (Nb / C) of Nb and C is 1 or more. Process heat treatment method of shape memory alloy.

(3) Nb, C-added Fe-Mn-Si-based shape memory alloy is an alloy component, Mn: 15 to 40% by weight, Si: 3 to 15% by weight, Cr: 1 to 20% by weight, Nb: 0.1 to 1.5 Nb according to item (1), wherein the balance comprises 0.01% to 0.2% by weight and the balance is made of Fe and unavoidable impurities, and the atomic ratio (Nb / C) between Nb and C is 1 or more; Process heat treatment method of C-added Fe-Mn-Si shape memory alloy.

(4) Nb and C-added Fe-Mn-Si-based shape memory alloys include, as alloy components, Mn: 15 to 40% by weight, Si: 3 to 15% by weight, Cr: 1 to 20% by weight, Ni: 0.1 to 20 The weight balance, Nb: 0.1 to 1.5% by weight, C: 0.01 to 0.2% by weight, the balance is made of Fe and unavoidable impurities, the atomic ratio (Nb / C) of Nb and C is 1 or more The heat treatment method of the Nb and C addition Fe-Mn-Si shape memory alloy of (1).

(5) The Nb and C-containing Fe-Mn-Si shape memory alloy according to any one of (2) to (4), wherein the atomic ratio of Nb and C is set in the range of 1.0 to 1.2. Processing heat treatment method.

(6) Nb and C-added Fe-Mn-Si-based memory alloys are impurities such as Cu: 3% by weight or less, Mo: 2% by weight or less, Al: 10% by weight or less, Co: 30% by weight or less and / or N: The heat treatment method of the Nb and C addition Fe-Mn-Si type memory alloy as described in any one of said (2)-(5) containing 5000 ppm or less.

(7) The conditions for aging heating are heated for 1 minute to 2 hours in a temperature range of 400 to 1000 ° C., the Nb-C-added Fe-Mn- according to any one of items (1) to (6) above. Process heat treatment method of Si type memory alloy.

[Effects of the Invention]

As a Fe-Mn-Si type memory alloy having a specific composition formed by adding Nb and C, in the conventional invention, the strain processing prior to aging is performed in a temperature range of 500 to 800 ° C. However, according to the present invention, the deformation processing prior to aging is successful by setting the deformation processing range within a specific range, thereby enabling the deformation processing at room temperature without using high temperature.

The technical significance of the present invention is clearly understood as compared with the configuration of the prior art and the prior art which presupposes that there is a clear and very large difference between them. That is, according to the present invention, it is successful to significantly improve the shape memory alloy for the first time by setting and combining a predetermined deformation ratio and an aging condition at a certain range at a specific alloy component and at room temperature. The operation exhibits a shape recovery rate equivalent to that of the sample subjected to the training treatment by an extremely general processing heat treatment such as deformation processing and aging at room temperature, and a remarkably larger recovery force can be obtained for the shape recovery power than the sample subjected to the training treatment. . In view of the present invention, it is expected that the use of the shape memory alloy will be accelerated for practical use in various fields.

Best Mode for Carrying Out the Invention

The reason why the strain ratio at room temperature is defined as 5 to 40% is that the strain ratio of less than 5% does not contribute effectively to the improvement of shape memory characteristics. If the strain ratio exceeds 40%, the sample becomes too hard. This is because deformation becomes remarkably difficult.

In addition, the chemical composition of the alloy targeted by the processing heat treatment method of the Nb, C-added Fe-Mn-Si-based shape memory alloy of the present invention, as indicated in the prior application, 1) Mn: 15 to 40% by weight, Si: It is an alloy containing 3-15 weight%, Nb: 0.1-1.5 weight%, C: 0.01-0.2 weight%, remainder consists of Fe and an unavoidable impurity, and the atomic ratio (Nb / C) of Nb and C is 1 or more. .

2) The alloying components of the Nb and C-added Fe-Mn-Si-based memory alloys are Mn: 15-40 wt%, Si: 3-15 wt%, Cr: 1-20 wt%, Nb: 0.1-1.5 wt% , C: 0.01 to 0.2% by weight, the balance is made of Fe and unavoidable impurities, the atomic ratio (Nb / C) of Nb and C is one or more.

3) The alloying components of the Nb- and C-added Fe-Mn-Si shape memory alloys include Mn: 15-40 wt%, Si: 3-15 wt%, Cr: 1-20 wt%, and Ni: 0.1-20 wt% And Nb: 0.1-1.5 weight%, C: 0.01-0.2 weight%, and remainder consists of Fe and an unavoidable impurity, and the atomic ratio (Nb / C) of Nb and C is one or more.

In any of the above-mentioned Nb and C addition Fe-Mn-Si type memory alloys, it is preferable that the atomic ratio (Nb / C) of Nb and C in an alloy is set to the range of 1.0-1.2.

In addition, the component of the alloy which the processing heat treatment method of the Fe-Mn-Si type memory alloy of this invention makes into an impurity is Cu: 3 weight% or less, Mo: 2 weight% or less, Al: 10 weight% or less, It is acceptable to include at least one group of Co: 30% by weight or less and N: 5000 ppm or less.

Embodiment of the Invention

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely based on FIG. 1 and FIG. However, since the examples shown in the drawings are disclosed as an example for easily understanding the present invention, the present invention is not limited thereto.

EXAMPLE

First, a Fe-28Mn-6Si-0.53Nb-0.06C alloy (value in weight%) formed by adding Nb and C of the present invention was prepared as a solvent. After the shape memory alloy is rolled at room temperature, it is shown below how the aging treatment is performed by heating for 1 minute to 2 hours in a temperature range of 400 to 1000 ° C.

1 is a graph showing a shape recovery rate when only aging is performed (rolling rate 0%) and when rolling at 10%, 20%, and 30% at room temperature. In all these cases, the aging treatment was carried out at 800 ° C. for 10 minutes. For comparison, a comparison result between the sample obtained by annealing and the sample trained five times for the Fe-28Mn-6Si-5Cr alloy to which Nb and C were not added is shown. The horizontal axis represents the initial strain amount (%) due to tensile deformation at room temperature, and the vertical axis represents the shape recovery rate (%) when the sample is heated to 600 ° C. In the case of heating to 400 ° C., almost the same shape recovery rate is obtained. The sample piece used for this experiment was a sample piece produced in thickness 0.6mm, width 1-4mm, and length (gauge length) 15mm.

As shown in this figure, the sample rolled at 10% has a shape memory recovery rate that is equivalent to or slightly lower than that of Nb and C-free alloys trained five times. Practically required initial strain amount is about 4%. Also in this amount of shape deformation, the shape memory recovery rate of about 90% strongly suggests that it can be used as a practical alloy. In order to obtain the same shape recovery rate as the conventional Fe-Mn-Si type memory alloy without Nb and C, at least five training sessions are required. As can be seen from this, the present invention exhibits shape memory characteristics in a simple manner.

Samples processed at a high rolling rate of 20% have a shape memory recovery rate that is approximately equal to or slightly higher than in the case of no machining (only aging). However, samples processed at high rolling rates higher than 30% have a lower shape memory recovery rate than when only the aging treatment is performed in the range of large initial strain.

On the other hand, the shape recovery force, which is one of the practically important shape memory characteristics, is significantly improved in the shape recovery power of 20% rolling and aging after 30% rolling. Fig. 2 is a graph showing a comparison between the case where only the aging treatment is performed (the rolling ratio is 0%) and the aging treatment is performed after the rolling is performed for 10%. The recovery force when the recovery strain of the abscissa is zero is that the stress generated when the sample is tensilely deformed at room temperature and then fixed at both ends of the sample so as not to recover until then is heated above the inverse transformation temperature and then returned to room temperature. it means. For example, the recovery force when the recovery strain is 2% means the stress generated when both ends of the sample are fixed after the recovery of the deformation is 2%. The initial shape deformation amount given at room temperature was 4-6% of the tests.

The test piece used at that time was the same test piece used to obtain the result shown in FIG. In FIG. 2, the recovery shape deformation amount of the horizontal axis is demonstrated about the case where a shape memory alloy is used for coupling, for example. The recovery strain is equivalent to the percentage of diameter to the degree of clearance allowed between the pipe and the coupling part (shape suppression alloy). This shape recovery force is remarkably improved in the range of high rolling rate. When the rolling rate is 20 to 30% at room temperature, a shape recovery force of 310 MPa is obtained at 0% recovery shape deformation, and a shape recovery force of 200 MPa is obtained at a recovery shape deformation amount of 2% with respect to the same rolling rate. Moreover, it turns out that the shape recovery force similar to the case of training is obtained also in the case of the rolling rate of 10%.

That is, as can be seen from the result of this figure (FIG. 2), in the case of the high rolling rate (20%, 30%) compared with the case where the rolling rate is 0% and 10%, the shape recovery force is remarkably. It is understood to be augmented. In addition, in FIG. 2, the shape recovery power of the sample without Nb and C addition and the sample trained 5 times for the comparison is shown. This figure shows that the resilience of these samples is much smaller than the resilience of the present invention.

As mentioned above, the present invention provides a Fe-Mn-Si-based shape memory alloy having a specific composition made by adding Nb and C, when the deformation treatment is in the range of a specific processing strain before aging treatment, at room temperature. It was the first time that it was possible to do so. The technical significance of the present invention is that the difference in the constitution of the present invention is comparable to that in the case of requiring training involving complicated operation or high temperature deformation processing at 500 to 800 ° C in the prior art. It appears so clearly that it can be clearly understood.

In other words, according to the present invention, the shape memory performance is greatly improved for the first time by setting and combining a specific alloy component, a specific deformation processing ratio at room temperature, and an aging condition in a certain range. The operation exhibits a shape recovery rate equivalent to that of the sample subjected to the training by an extremely general heat treatment such as strain processing and aging at room temperature, and a remarkably larger recovery force can be obtained for the shape recovery power than the sample subjected to the training treatment. Will be. After all, the significance of the present invention is extremely large. Since the shape memory alloy according to the present invention can be used as a fastening member for various uses, such as fastening of water pipes and fastening of oil pipes, economical effects are greatly exhibited.

The use as the fastening member mentioned above shows a simple example, and the present invention is not limited to this use. In the various fields of the present invention, it is expected that the shape memory alloy is practically used in various applications.

The present invention provides a processing heat treatment means for a Fe-Mn-Si-based shape memory alloy having a specific composition made by adding Nb and C, which has been subjected to simple deformation processing before aging. In the conventional invention, the deformation treatment prior to aging is performed in a temperature range of 500 to 800 ° C. However, according to the present invention, when the strain processing rate is within a specific range, the strain processing preceded by aging succeeds in enabling strain processing at room temperature without depending on the high temperature.

The technical significance of the present invention is clearly understood as compared with the configuration of the prior art and the prior art which presupposes that there is a clear and very large difference between them. That is, according to the present invention, it is successful to significantly improve the shape memory alloy for the first time by setting and combining a predetermined deformation ratio and an aging condition at a certain range at a specific alloy component and at room temperature.

The technical significance of the present invention is clearly understood as compared with the configuration of the prior art and the prior art which presupposes that there is a clear and very large difference between them. That is, according to the present invention, it is successful to significantly improve the shape memory alloy for the first time by setting and combining a predetermined deformation ratio and an aging condition at a certain range at a specific alloy component and at room temperature. The operation exhibits a shape recovery rate equivalent to that of the sample subjected to the training treatment by an extremely general processing heat treatment such as deformation processing and aging at room temperature, and a resilience significantly higher than that of the sample subjected to the training treatment for the shape recovery power. do. In view of the present invention, it is expected that the use of the shape memory alloy will be accelerated for practical use in various fields.

Claims (7)

Transforming the Fe—Mn—Si-based shape memory alloy formed by adding Nb and C at a strain ratio of 5 to 40% at room temperature; Aging and heat-treating the strain-processed alloy to precipitate NbC carbide, characterized in that the Nb, C addition Fe-Mn-Si-based shape memory alloy processing heat treatment method. The method of claim 1, The said Nb and C addition Fe-Mn-Si type memory alloy is an alloy component, Mn: 15-40 weight%, Si: 3-15 weight%, Nb: 0.1-1.5 weight%, C: 0.01-0.2 weight% And a balance comprising Fe and unavoidable impurities, wherein the atomic ratio (Nb / C) of Nb and C is 1 or more. The heat treatment method for Nb- and C-added Fe-Mn-Si shape memory alloys. The method of claim 1, The Nb, C-added Fe-Mn-Si-based shape memory alloy is an alloy component, Mn: 15 to 40% by weight, Si: 3 to 15% by weight, Cr: 1 to 20% by weight, Nb: 0.1 to 1.5% by weight , C: 0.01 to 0.2% by weight, the remainder is composed of Fe and unavoidable impurities, Nb, C addition Fe-Mn-Si-based shape, characterized in that the atomic ratio (Nb / C) of Nb and C is 1 or more Process heat treatment method of memory alloy. The method of claim 1, The said Nb and C addition Fe-Mn-Si type memory alloy is an alloy component, Mn: 15-40 weight%, Si: 3-15 weight%, Cr: 1-20 weight%, Ni: 0.1-20 weight% And Nb: 0.1 to 1.5% by weight, C: 0.01 to 0.2% by weight, the balance consisting of Fe and unavoidable impurities, and Nb and C, wherein the atomic ratio (Nb / C) of Nb and C is 1 or more. Process heat treatment method of addition Fe-Mn-Si-based shape memory alloy. The method according to any one of claims 2 to 4, An atomic ratio of said Nb and C is set in the range of 1.0-1.2, The heat processing method of the Nb and C addition Fe-Mn-Si type memory alloy. The method according to any one of claims 2 to 5, The Nb- and C-added Fe-Mn-Si-based shape memory alloys are impurities such as Cu: 3 wt% or less, Mo: 2 wt% or less, Al: 10 wt% or less, Co: 30 wt% or less and / or N: A process heat treatment method for Nb and C-added Fe-Mn-Si shape memory alloys containing 5000 ppm or less. The method according to any one of claims 1 to 6, Process for heat treatment of Nb, C-containing Fe-Mn-Si shape memory alloy, characterized in that the conditions of the aging heat treatment is heated for 1 minute to 2 hours in the temperature range of 400 to 1000 ℃.