TW201812041A - Nickel-based alloy and method of producing thereof - Google Patents

Abstract

The present invention provides a method of producing a nickel-based alloy. The method comprises performing a first heat treatment, a cold working treatment and an aging treatment on an alloy plate. Alternatively, the method comprises performing a second heat treatment between the cold working treatment and the aging treatment, so as to increasing a flexibility of a process time of the aging treatment, thereby forming the nickel-based alloy with good strength and elongation at a room temperature.

Description

 Nickel base alloy and its manufacturing method  

The invention relates to a nickel-based alloy and a manufacturing method thereof, and particularly relates to a nickel-based alloy which can be combined with strength and ductility at normal temperature by a specific heat treatment, cold working treatment and aging heat treatment. A method of manufacturing a nickel-based alloy.

Common nickel-based alloys (such as Alloy 718, A-286, and X-750), because of their high temperature strength, high temperature oxidation resistance, and good corrosion resistance, are often used in high temperature mechanical properties, such as : Engine components, turbine engine fasteners, high temperature bearings, furnace enclosures or nuclear power plant furnaces. Since the main component of the nickel-based alloy is nickel, its structure is mainly face-centered cubic structure, while the precipitation strengthening phase is mainly the γ' phase (Ni ₃ (Ti, Al)) of the Ll ₂ structure and the γ" phase of the DO ₂₂ structure ( Ni ₃ Nb) Further, by the heat treatment process, fine δ phase (Ni ₃ Nb) precipitates can be precipitated on the grain boundaries, and the movement of the grain boundaries can be controlled to achieve the effect of fine crystals.

In order to enhance the effect of precipitation strengthening, the nickel-based alloy having the precipitation strengthening phase needs to be subjected to solution heat treatment to completely dissolve the precipitation strengthening elements such as aluminum, titanium and niobium in the base phase γ phase to be strengthened in the subsequent heat treatment. The strength of nickel based alloys. However, the nickel-based alloy produced can only achieve a tensile strength of about 1400 MPa, a relief strength of about 1200 MPa, and an elongation of about 20% by using a solution heat treatment combined with an aging heat treatment.

If used in the petrochemical industry to develop oil-drilled bearings for oil wells, the nickel-based alloys used need to have higher strength and durability at room temperature to avoid the risk of brittle fracture. However, the nickel-based alloy produced by the above-described manufacturing method, although having an appropriate elongation to improve durability, is insufficient in strength and thus cannot be applied to the formed oil bearing.

Therefore, there is an urgent need to propose a nickel-based alloy and a method for producing the same, which can make the obtained nickel-based alloy have good strength and ductility at normal temperature, thereby making the application range of the nickel-based alloy wider.

Therefore, an aspect of the present invention provides a method for producing a nickel-based alloy which utilizes a first heat treatment, a cold working treatment, and an aging heat treatment to obtain a specific tensile strength, a fall strength, and an elongation at a normal temperature. F. Alternatively, a second heat treatment may be added between the cold working treatment and the aging heat treatment to increase the time elasticity of the aging heat treatment.

Another aspect of the present invention is to provide a nickel-based alloy which can combine strength and ductility at normal temperature.

According to the above aspect of the invention, a method of producing a nickel-based alloy is proposed. In an embodiment, the above manufacturing method may include the following steps. First, an alloy processed material is provided which may be composed of 15 weight percent (wt.%) to 25 wt.% chromium, 10 wt.% to 20 wt.% iron, 0.02 wt.% to 0.08 wt.%. Carbon, greater than 0 to 6 wt.% aluminum, greater than 0 to 6 wt.% titanium, greater than 0 to 5 wt.% bismuth, 10 wt.% to 75 wt.% nickel, and less than 3 wt.% other impurity elements. Next, the above-mentioned alloy processed material is subjected to a first heat treatment to form a solid solution, wherein the first heat treatment can be performed at a first temperature of 950 ° C to 980 ° C. Then, the solid solution material is subjected to a cold working treatment to form a cold processed material, wherein the reduction rate of the cold working treatment may be 20% to 30%. Thereafter, the cold worked material is subjected to an aging heat treatment to obtain a nickel-based alloy.

According to an embodiment of the present invention, the foregoing aging heat treatment may further include a first stage aging heat treatment and a second stage aging heat treatment. Wherein, the first stage aging heat treatment can be performed at a second temperature of 650 ° C to 780 ° C, and the second stage aging heat treatment can be performed at a third temperature of 550 ° C to 650 ° C.

According to an embodiment of the present invention, between the cold working treatment and the aging heat treatment, the second heat treatment of the cold worked material may be further included, and the second heat treatment may be performed at a fourth temperature of 800 ° C to 1000 ° C.

According to an embodiment of the present invention, the aforementioned first heat treatment may be performed for 10 minutes to 60 minutes.

According to an embodiment of the invention, the second heat treatment can be carried out for 5 minutes to 2 hours.

According to an embodiment of the present invention, the first-stage aging heat treatment after the second heat treatment is performed for 1 hour to 100 hours.

According to an embodiment of the present invention, the second-stage aging heat treatment after the second heat treatment is performed for 1 hour to 1000 hours.

According to an embodiment of the present invention, the first stage aging heat treatment without performing the second heat treatment may be performed for 8 hours to 12 hours.

According to an embodiment of the present invention, the second stage aging heat treatment in which the second heat treatment is not performed is carried out for 18 hours to 22 hours.

According to the above aspect of the invention, a nickel-based alloy is further proposed. In one embodiment, the above nickel-based alloy is produced by the above-described method for producing a nickel-based alloy. The nickel-based alloy may have a tensile strength of not more than 1670 MPa, a relief strength of not less than 1400 MPa, and an elongation of not less than 10%.

The method for producing a nickel-based alloy according to the present invention can be obtained by a specific first heat treatment, cold working treatment and aging heat treatment, or selectively between a cold working treatment and an aging heat treatment, by adding a second heat treatment. Nickel-based alloys have good strength and ductility at room temperature.

An aspect of the present invention provides a nickel-based alloy and a method for producing the same, which are to apply a specific process step such as a first heat treatment, a cold working treatment, and an aging heat treatment to an alloy processed material having a specific composition, and are selective for the above A second heat treatment is performed between the cold working treatment and the aging heat treatment to produce a predetermined nickel-based alloy. The above nickel-based alloy can have both good strength and ductility at normal temperature.

The alloy processed material referred to herein as the alloy processing material may be an alloy processed sheet, an alloy wire or other processed alloy material. Processing referred to herein includes rolling or drawing.

The term "normal temperature" as used herein means 0 ° C to 50 ° C.

The strength referred to herein as the strength may include the strength of the fall and the tensile strength.

The ductility referred to herein as the ductility can be evaluated by elongation.

Hereinafter, the respective process stages in the composition of the alloy processed material of the present invention and the manufacturing method will be described in order.

Alloy processing material

The alloy processed material of the present invention may be composed of the following elements: 15 wt.% to 25 wt.% of chromium, 10 wt.% to 20 wt.% of iron, 0.02 wt.% to 0.08 wt.% of carbon, and more than 0 to 6 wt. % aluminum, greater than 0 to 6 wt.% titanium, greater than 0 to 5 wt.% bismuth, 10 wt.% to 75 wt.% nickel, and less than 3 wt.% other impurity elements.

In one example, the alloy working material may be formed by a process such as a melting step, a casting step, a cold/hot processing step, and a cutting step. In one example, the smelting step can be, for example, vacuum induction melting, arc melting, or other conventional smelting methods. The casting step can be, for example, continuous casting or die casting. The cold/hot processing steps can be, for example, cold rolling, hot rolling, and/or other conventional cold/hot processing methods. It should be noted that the size and type of the alloyed material (for example, sheet or wire) are determined according to the application of the produced nickel-based alloy, and the invention is not limited.

The chromium in the above-mentioned alloy processed material can increase the corrosion resistance of the obtained nickel-based alloy, and if the above-mentioned chromium content is less than 15 wt.%, the obtained nickel-based alloy has poor corrosion resistance.

The iron in the above-mentioned alloy processed material can complement other components other than the essential elements of the alloy processed material to reduce the manufacturing cost of the nickel-based alloy. If the iron content is less than 10 wt.%, the manufacturing cost of the nickel-based alloy increases, which is not in line with economic considerations.

The carbon in the above alloy processed material can strengthen the strength of the nickel-based alloy, so if the carbon content is less than 0.02 wt.%, the strength of the nickel-based alloy is not good. However, if the carbon content is more than 0.08 wt.%, the brittleness of the nickel-based alloy increases to cause deterioration in ductility.

The aluminum, titanium and niobium in the above-mentioned alloy processed material are precipitation strengthening elements, and the presence of the above elements in combination with the specific process of the present invention contributes to an increase in the strength of the obtained nickel-based alloy at normal temperature. Therefore, if aluminum alloy, titanium, and tantalum are not contained in the alloy processed material, the strength of the obtained nickel-based alloy at normal temperature is not good. On the other hand, if the content of aluminum, titanium or niobium is larger than the range claimed in the present invention, the corrosion resistance of the nickel-based alloy is not good, and the alloy material described above is not easily refined into an alloy processed material.

The impurity element referred to above may be, for example, ruthenium, molybdenum, copper, manganese or other elements, and excessive impurity elements may affect the precipitation phase of the nickel-based alloy, and the content thereof should not exceed the range claimed by the present invention.

Method for manufacturing nickel base alloy

First heat treatment

The method for producing a nickel-based alloy according to the present invention first provides an alloy processed material as described above, and performs a first heat treatment on the alloy processed material to form a solid solution. In one embodiment, the first heat treatment of the present invention is carried out at a first temperature of from 950 ° C to 980 ° C for from 10 minutes to 60 minutes.

The first heat treatment is a solution annealing treatment which removes residual stress generated when the alloy processed material is subjected to the aforementioned cold/hot processing step (for example, rolling). In addition, in the first heat treatment, the precipitation strengthening element of the alloy processed material can precipitate fine δ precipitates on the grain boundary of the alloy processed material to control the grain boundary movement of the alloy processed material, thereby achieving grain refinement. The effect is that the nickel-based alloy can have an appropriate grain size.

If the first temperature is higher than 980 ° C, the δ precipitates are melted and the movement of the grain boundaries cannot be restricted, and the obtained nickel-based alloy has the disadvantage that the crystal grains are coarsened and the strength and ductility are lowered. On the other hand, if the first temperature is less than 950 ° C, the precipitation of the precipitation strengthening element is not good, and the movement of the grain boundary cannot be effectively controlled.

2. Cold processing

Next, the solid solution material is subjected to a cold working treatment to cure the solid solution material to form a cold-worked material having improved strength. In an embodiment, the reduction rate of the cold working treatment may be 20% to 30%.

In one example, the cold working process described above may be cold rolling. In other examples, the cold working process can be extrusion or extraction.

In one example, the cold working is carried out at a temperature of from 0 °C to 50 °C.

If the above reduction rate is less than 20%, the strength of the nickel-based alloy cannot be effectively improved. On the other hand, if the reduction rate is more than 30%, the ductility of the nickel-based alloy is deteriorated.

3. Second heat treatment

Thereafter, the cold processed material may be selectively subjected to a second heat treatment. In an embodiment, the second heat treatment may be performed at a fourth temperature of 800 ° C to 1000 ° C for 5 minutes to 2 hours. By the second heat treatment, the residual stress of the cold worked material can be eliminated to increase the ductility of the produced nickel-based alloy.

If the fourth temperature is less than 800 ° C or the time of the second heat treatment is too short, the residual stress of the cold worked material cannot be effectively eliminated. On the other hand, if the fourth temperature is more than 1000 ° C, the strength of the obtained nickel-based alloy is insufficient. Further, if the second heat treatment is too long, the harmful phase (for example, a brittle phase) is precipitated, and the ductility of the nickel-based alloy is also lowered.

4. Aging heat treatment

Next, the cold-worked material is subjected to an aging heat treatment to adjust the strength and ductility of the cold-worked material to a predetermined range to obtain a nickel-based alloy of the present invention. In an embodiment, the aging heat treatment may include a first stage aging heat treatment and a second stage aging heat treatment. Preferably, the first stage aging heat treatment can be carried out at 650 ° C to 780 ° C, and the second stage aging heat treatment can be carried out at 550 ° C to 650 ° C.

In one example, the first stage aging heat treatment can be carried out, for example, in a furnace cooling manner, and the second stage aging heat treatment can be carried out, for example, in an air cooling manner.

Specifically, the aging heat treatment referred to in the present invention is slightly different in the first-stage aging heat treatment and the second-stage aging heat treatment depending on whether or not the second heat treatment is performed, which will be described below.

In one embodiment, the cold worked material is directly subjected to an aging heat treatment without performing a second heat treatment. In this embodiment, the first stage aging heat treatment is preferably carried out for 8 hours to 12 hours, and the second stage aging heat treatment is preferably carried out for 18 hours to 22 hours. An embodiment in which the second heat treatment is not performed, and the aging heat treatment is directly performed, which will be described later in the present invention, is referred to as long-time aging heat treatment.

In another embodiment, the cold worked material is subjected to an aging heat treatment after the second heat treatment. In this embodiment, the first stage aging heat treatment is preferably carried out for 1 hour to 100 hours, and the second stage aging heat treatment is preferably carried out for 1 hour to 1000 hours. An embodiment in which the aging heat treatment is performed after the second heat treatment is described later in the present invention is referred to as short-time aging heat treatment. In particular, the short-time aging heat treatment performed after the second heat treatment is performed, and the adjustable time range is large. In one example, the first stage heat treatment and the second stage heat treatment can be carried out for 1 hour, respectively. In another example, the time of the first stage heat treatment and the second stage heat treatment may be extended in conjunction with the overall process. Therefore, performing the second heat treatment can increase the process flexibility of the aging heat treatment.

If the first-stage aging heat treatment and the second-stage aging heat treatment are not divided, the aging treatment is performed on the cold-worked materials at different temperatures and times, and a harmful phase (such as the brittle phase described above) is easily generated during the aging heat treatment, and further The nickel-based alloy cannot be combined to have a predetermined strength and ductility.

If the progress time of the long-time aging heat treatment is shortened to the progress time of the short-time aging heat treatment, the aging heat treatment time is insufficient, and the nickel-based alloy cannot achieve the predetermined strength and ductility.

5. Other processing

In one embodiment, the alloy processed material is an alloy sheet, and the nickel-based alloy obtained by the alloy is further subjected to a sandblasting, pickling, and leveling process to obtain a nickel-based alloy sheet product.

In another embodiment, the alloy processed material is a wire, and the nickel-based alloy obtained can be further peeled, pickled or straightened to obtain a nickel-based alloy straight bar type product.

F

The nickel-based alloy obtained by the above-described method for producing a nickel-based alloy according to the present invention may have a tensile strength of not more than 1,670 MPa, a relief strength of not less than 1400 MPa, and an elongation of not less than 10%.

Preferably, the nickel-based alloy of the present invention can be applied to fields requiring high strength materials such as steam turbines or oil bearing bearings. Since the nickel-based alloy of the present invention is more ductile, the durability and work efficiency in the above fields can be improved.

Hereinafter, a method for producing a nickel-based alloy of the present invention will be specifically described using a plurality of examples.

Example 1

First, an alloy sheet having an elemental composition as shown in Table 1 was provided. Next, the above alloy sheet was heat-treated at 980 ° C for 60 minutes. Then, cold rolling was performed at room temperature (30 ° C) to bring the reduction rate to 20%. Further, after the first-stage heat treatment at 720 ° C for 10 hours, the second-stage heat treatment was carried out at 650 ° C for 18 hours to obtain the nickel-based alloy of Example 1. The specific process conditions and evaluation results of Example 1 are shown in Table 2.

Example 2 and Comparative Examples 1 to 6

Example 2 and Comparative Examples 1 to 6 were carried out using the same alloy sheet as in Example 1, except that Example 2 and Comparative Examples 1 to 6 were used to change the process conditions. The process conditions and evaluation results specific to Example 2 and Comparative Examples 1 to 6 are shown in Table 2 and will not be further described herein.

Evaluation method

Tensile strength

The tensile strength of the present invention was tested on the nickel-base alloys of Examples 1 to 2 and Comparative Examples 1 to 6 at room temperature (0 to 50 ° C) using a standard test method ASTM E112. In general, the nickel-based alloy of the present invention may have a tensile strength of not more than 1670 MPa. More preferably, the above tensile strength may be from more than 1400 MPa to not more than 1670 MPa.

2. Falling strength

The lodging strength of the present invention was tested on the nickel base alloys of Examples 1 to 2 and Comparative Examples 1 to 6 at room temperature (0 to 50 ° C) using a standard test method ASTM E112. In general, the nickel-based alloy of the present invention may have a fall strength of not less than 1400 MPa.

3. Elongation

The elongation of the present invention was tested on the nickel base alloys of Examples 1 to 2 and Comparative Examples 1 to 6 at room temperature (0 to 50 ° C) using a standard test method ASTM E112. In general, the elongation of the nickel-based alloy of the present invention is preferably not less than 10%.

It should be noted that the predetermined nickel-based alloy of the present invention needs to have good strength and ductility at normal temperature, and therefore it is necessary to satisfy the above-mentioned predetermined tensile strength, lodging strength and elongation.

As is apparent from the evaluation results of Table 2, in Example 1 of the present invention, the long-term aging heat treatment was carried out without performing the second heat treatment, and the obtained nickel-based alloy had both good strength and ductility. Further, in the nickel-based alloy of the second embodiment of the present invention, the time for the subsequent aging heat treatment (i.e., the short-time aging heat treatment) is shortened by the second heat treatment, and the obtained nickel-based alloy can also have both strength and ductility.

On the other hand, according to Comparative Examples 1 and 2, if the cold working treatment is not performed, even if the aging heat treatment is performed, the strength which can be lifted is limited, and the predetermined strength cannot be obtained. Further, as can be seen from Comparative Examples 3 to 5, if the second heat treatment and/or the aging heat treatment were not performed, even if the reduction rate of the cold working treatment was increased, only the strength was increased, but the ductility was deteriorated. Further, as shown in Comparative Example 6, if only a short-time aging heat treatment was applied without performing the second heat treatment, the obtained nickel-based alloy could not have both strength and ductility.

The nickel-based alloy of the present invention and the method for producing the same, the first heat treatment, the cold working and the aging heat treatment are carried out by using the alloy material of a specific composition, and the second heat treatment can be selectively added to shorten the time course of the aging heat treatment, and the method can be obtained. A nickel-based alloy that combines strength and ductility at room temperature.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the scope of the appended claims.

Claims (10)

 A method for producing a nickel-based alloy, comprising: providing an alloy processing material, which is composed of the following elements: 15 weight percent (wt.%) to 25 wt.% chromium; 10 wt.% to 20 wt.% iron; 0.02 wt.% to 0.08 wt.% carbon; greater than 0 to 6 wt.% aluminum; greater than 0 to 6 wt.% titanium; greater than 0 to 5 wt.% bismuth; 10 wt.% to 75 wt.% nickel; And less than 3 wt.% of other impurity elements, the first processed portion of the alloy processed material is formed to form a solid solution, wherein the first heat treatment is performed at a first temperature of 950 ° C to 980 ° C; the solid solution material A cold working treatment is performed to form a cold-worked material, wherein the cold-cutting treatment has a reduction ratio of 20% to 30%; and the cold-worked material is subjected to an aging heat treatment to obtain the nickel-based alloy.    The method for producing a nickel-based alloy according to claim 1, wherein the aging heat treatment further comprises: a first-stage aging heat treatment, wherein the first-stage aging heat treatment is performed at a second temperature of 650 ° C to 780 ° C And performing a second-stage aging heat treatment, wherein the second-stage aging heat treatment is performed at a third temperature of 550 ° C to 650 ° C.    The method for producing a nickel-based alloy according to claim 2, further comprising: performing a second heat treatment on the cold worked material between the cold working treatment and the aging heat treatment, and the second heat treatment is performed at 800 ° C to It is carried out at one of 1000 ° C and a fourth temperature.    The method for producing a nickel-based alloy according to claim 1, wherein the first heat treatment is performed for 10 minutes to 60 minutes.    The method for producing a nickel-based alloy according to claim 3, wherein the second heat treatment is performed for 5 minutes to 2 hours.    The method for producing a nickel-based alloy according to claim 3, wherein the first-stage aging heat treatment is performed for 1 hour to 100 hours.    The method for producing a nickel-based alloy according to claim 3, wherein the second-stage aging heat treatment is performed for 1 hour to 1000 hours.    The method for producing a nickel-based alloy according to claim 2, wherein the first-stage aging heat treatment is performed for 8 hours to 12 hours.    The method for producing a nickel-based alloy according to claim 2, wherein the second-stage aging heat treatment is carried out for 18 hours to 22 hours.    A nickel-based alloy obtained by the method for producing a nickel-based alloy according to any one of claims 1 to 9, wherein the nickel-based alloy has a tensile strength of not more than 1670 MPa and not less than 1400 MPa. One of the strength of the fall and an elongation of not less than 10%.