JP3271499B2 - Method for producing high-strength corrosion-resistant Ni-based alloy sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an N-type steel sheet having high strength and excellent corrosion resistance and having a thickness of 0.01 to 0.5 mm.
The present invention relates to a method for producing an i-base alloy thin plate.

[0002]

2. Description of the Related Art Conventionally, as described in, for example, JP-A-6-116666, weight% (hereinafter,% is weight%).
), Cr: 14 to 23%, Mo: 14 to 2
0%, W: 0.2-5%, Fe: 0.2-7
%, Co: 0.2-2.5%, the balance being Ni and unavoidable impurities, a high-strength corrosion-resistant Ni-based alloy plate is used to support diaphragms, relay contacts of electronic circuits, and magnetic heads. Applied to manufacture of springs and the like.
Further, the high-strength corrosion-resistant Ni-based alloy sheet is (a) a hot-rolled sheet having a sheet thickness of 5 to 15 mm by repeatedly performing hot rolling after solution treatment of an ingot of the above composition;
The hot-rolled sheet is repeatedly subjected to cold rolling while being subjected to intermediate annealing. At this time, cold rolling after final intermediate annealing is performed at a rolling ratio per pass of 2 to 4% at 50 passes or more. A cold-rolled sheet having a thickness of 0.7 to 1.5 mm; (c) placing the cold-rolled sheet in a reducing atmosphere or an inert gas atmosphere;
It is also known to be manufactured by performing a batch aging treatment at a temperature of 00 to 600 ° C. for 0.5 hour or more.

[0003]

On the other hand, in recent years, various types of control equipment and electronic and electrical equipment tend to be reduced in size and weight. Smaller and thinner springs are also required to be made smaller.Thus, it is indispensable to reduce the thickness of the high-strength corrosion-resistant Ni-based alloy plate used for manufacturing these structural parts. Since the Ni-base alloy plate is made of a Ni-base alloy that is difficult to cold-roll, the cold rolling after the final intermediate annealing as in the above-described manufacturing method is performed by reducing the rolling reduction per pass. Therefore, it is inevitable to take rolling conditions for performing more than 50 passes, and it is extremely difficult at present to reduce the final sheet thickness to 0.7 mm or less even under such cold rolling conditions. .

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, research was conducted to produce Ni-based alloy thin plates having the same high strength and excellent corrosion resistance as the above-mentioned conventional Ni-based alloy plates and having a final thickness of 0.7 mm or less. As a result, in the above-mentioned conventional method for producing a high-strength corrosion-resistant Ni-based alloy sheet, the ingot was made of Cr: 20 to 22.
5%, Mo: less than 12.5 to 14%, W: 2.5
~ 3.5%, Fe: 2 ~ 6%, Co: 0.2 ~
2.5%, and the balance is made of a Ni-base alloy having a composition consisting of Ni and unavoidable impurities, the rolling reduction per pass in cold rolling after final intermediate annealing of cold rolling is 6 to 12%. %, And the repetition (multi-pass) does not deteriorate the rollability. Therefore, the final plate thickness is 0.7 mm or less, particularly 0.01 to 0.5 mm, which is particularly required.
In the continuous aging treatment due to the high residual stress generated at such a high rolling reduction, a fine and large amount of the Ni-Mo intermetallic compound has a structure in which the Ni-Mo based intermetallic compound is uniformly dispersed and distributed in the austenitic base material. Therefore, it is possible to manufacture a Ni-based alloy sheet having high strength and excellent corrosion resistance due to the austenite phase of the base.

The present invention has been made on the basis of the above-mentioned research results, and (a) Cr: 20 to 22.5
%, Mo: 12.5 to less than 14%, W: 2.5 to
3.5%, Fe: 2 to 6%, Co: 0.2 to 2.
After the Ni-based alloy ingot containing 5%, the balance of which is composed of Ni and unavoidable impurities, is homogenized, hot rolling is repeatedly performed to form a hot-rolled sheet having a thickness of 5 to 15 mm, (B) The above hot-rolled sheet is repeatedly subjected to cold rolling while being subjected to intermediate annealing. At this time, the cold rolling after the final intermediate annealing is performed at a rolling reduction per pass of 6 to 12% and 5%.
To 15 passes, and the final thickness is 0.01 to 0.1.
(C) subjecting the cold-rolled sheet to a continuous aging treatment in a reducing atmosphere or an inert gas atmosphere at a temperature of 500 to 800 ° C. for 0.5 to 5 minutes;
According to the basic steps (a) to (c), high strength corrosion resistance Ni
The present invention is characterized by a method of manufacturing a base alloy thin plate.

Next, the reason why the manufacturing conditions are limited as described above in the method of the present invention will be described. (1) Ingot composition (a) Cr The Cr component has the effect of significantly improving the passivation of the austenitic substrate and exhibiting excellent corrosion resistance, particularly in an atmosphere exposed to oxidizing acids. If the content is less than 20%, desired excellent corrosion resistance cannot be ensured. On the other hand, if the content exceeds 22.5%, the cold-rolling property decreases, so that the content is reduced. Was determined to be 20 to 22.5%.

(B) Mo The Mo component has a function of improving the strength by forming a Ni-Mo intermetallic compound which is uniformly and finely dispersed and deposited on the austenite substrate during the continuous aging treatment.
If it is less than 2.5%, the desired strength cannot be ensured, while if its content exceeds 14%, the cold rollability, particularly after final intermediate annealing, is reduced, and the rolling reduction per pass is reduced. Since the content cannot be increased to 6% or more and it becomes difficult to reduce the thickness, the content is set to 12.5 to less than 14%.

(C) WW The W component has the effect of forming a solid solution in the austenite matrix and strengthening it, but if the content is less than 2.5%, the desired base cannot be strengthened. On the other hand, if the content exceeds 3.5%, the hot and cold rollability decreases, so the content was determined to be 2.5 to 3.5%.

(D) Fe The Fe component has an effect of improving the cold rolling property especially after the final intermediate annealing in the cold rolling step, but if its content is less than 2%, the desired effect on the above effect is obtained. If the effect is not obtained, and if the content exceeds 6%, the strength decreases, so the content is set to 2 to 6%.

(E) Co The Co component has a function of improving the corrosion resistance by forming a solid solution in the austenite base, but if its content is less than 0.2%, the desired effect of improving the corrosion resistance cannot be obtained. If the content exceeds 2.5%, the precipitation of the Ni—Mo intermetallic compound will be suppressed during the continuous aging treatment.
Its content was determined to be 0.2-2.5%.

(2) Sheet thickness of hot-rolled sheet If the sheet thickness is less than 5 mm, the rolling reduction in the cold rolling step becomes low, and it becomes difficult to secure a desired high strength after continuous aging treatment. When the thickness exceeds 15mm,
On the contrary, since the number of rolling passes in the cold rolling process is increased and it is not economical, the thickness is set to 5 to 15 mm.

(3) Rolling rate per pass and number of passes in cold rolling after final intermediate annealing Even if the rolling rate per pass is less than 6% or the rolling rate is 6% or more. If the number of passes is less than 5 or more, sufficient residual stress cannot be applied to the cold-rolled sheet, and as a result, precipitation of the Ni—Mo intermetallic compound during continuous aging treatment becomes insufficient, which is undesirable. When the rolling ratio per pass exceeds 12% or the number of passes exceeds 15 passes, cracks are likely to occur at both ends of the cold-rolled sheet. The rolling reduction per pass in cold rolling after the final intermediate annealing is 6-1 to 1
2% and the number of passes was determined to be 5 to 15 times.

(4) Temperature and time of continuous aging treatment Even if the temperature is lower than 500 ° C., and the holding time is 0.1 mm.
Even if it is less than 5 minutes, the precipitation of the Ni-Mo intermetallic compound becomes insufficient, and the desired high strength cannot be secured. On the other hand, if the temperature exceeds 800 ° C or the holding time exceeds 5 minutes, Since the crystal growth occurs and the strength decreases, the temperature is set to 500 to 800 ° C. and the holding time is set to 0.5 to 5 minutes.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A Ni-base alloy melt having the composition shown in Table 1 is prepared in a normal high-frequency induction furnace, cast and cast into a Ni-base alloy of the present invention having a size of 50 mm × 150 mm × 300 mm. After forming an ingot (for the method of the present invention) and a conventional Ni-based alloy ingot (for the conventional method), these ingots were subjected to a homogenization treatment at a temperature of 1230 ° C. for 6 hours, and then within a range of 900 to 1230 ° C. Hot rolling at a predetermined temperature is performed a predetermined number of times within a range of 5 to 12 times to obtain a hot-rolled sheet having a thickness shown in Table 2, and the hot-rolled sheet is subjected to a predetermined rolling within a range of 5 to 15%. Cold rolling at a rate of 1120 to 1200
The intermediate annealing at a predetermined temperature within the range of ℃ is one cycle,
This was performed for the number of cycles shown in Table 2 to obtain a sheet thickness also shown in Table 2, and subsequently subjected to cold rolling under the conditions shown in Table 2 to obtain a final sheet thickness also shown in Table 2. Using a bright annealing furnace, aging treatment was performed in a hydrogen atmosphere under the conditions shown in Table 2 to carry out the present invention methods 1 to 3 and the conventional method, thereby producing a Ni-based alloy sheet and a Ni-based alloy sheet, respectively. did.

[0015]

[Table 1]

[0016]

[Table 2]

Next, in order to evaluate the strength of the various Ni-based alloy sheets and Ni-based alloy sheets obtained as described above, a Schenk-type plane bending fatigue tester was used. × A curved surface R15 with cutouts on both sides at the center and a minimum width of 10 mm at the center. Atmosphere: Atmosphere at room temperature. Stress ratio: Swing (R = -1). Frequency: 25 Hz. ^The critical stress that did not break after ^seven cycles) was measured. This measurement is shown in Table 2.

[0018]

According to the results shown in Table 2, the methods 1 to 5 of the present invention were used.
According to No. 3, it is possible to manufacture a Ni-based alloy thin plate having the same high strength as the Ni-based alloy plate manufactured by the conventional method, and even if the number of rolling passes after the final intermediate annealing is increased in the conventional method, It is clear that rolling can be performed with a relatively low number of rolling passes to a thickness of 0.01 to 0.5 mm, which was impossible to achieve a thickness of 0.7 mm or less. As described above, according to the method of the present invention, it has a high strength equivalent to that of a corrosion-resistant Ni-based alloy plate having a relatively high Mo content, and has a relatively small plate thickness. 01-0.5mm
Can be manufactured, and the resulting high-strength corrosion-resistant Ni-based alloy sheet can have a significantly reduced thickness as described above. Industrially useful effects can be brought about, such as a sufficient reduction in size and weight.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-116666 (JP, A) JP-A-7-70682 (JP, A) JP-A-7-178574 (JP, A) JIS Handbook Iron and Steel, Japan , Japan Standards Association, April 20, 1990, p. 1823 (58) Field surveyed (Int. Cl. ⁷ , DB name) C22F 1/10 B21B 1/00-3/00 C22C 19/00-19/05

Claims (1)

(57) [Claims] (1) Cr: 20 to 22.5%, Mo: 12.
5 to less than 14%, W: 2.5 to 3.5%, Fe: 2 to 6%, Co: 0.2 to 2.5%, the balance being composed of Ni and inevitable impurities. After the Ni-based alloy ingot is homogenized, hot rolling is repeatedly performed to form a hot-rolled sheet having a thickness of 5 to 15 mm. (B) The hot-rolled sheet is repeatedly subjected to cold rolling while being subjected to intermediate annealing. At this time, the cold rolling after the final intermediate annealing is performed under the conditions of 5 to 15 passes at a rolling reduction per pass: 6 to 12% and a final sheet thickness of 0.01 to 0.5 mm. (C) subjecting the cold-rolled sheet to a continuous aging treatment in a reducing atmosphere or an inert gas atmosphere at a temperature of 500 to 800 ° C. for 0.5 to 5 minutes. A method for producing a high-strength corrosion-resistant Ni-based alloy sheet.