JPH0297651A - Free cutting austenitic stainless steel excellent in controlled rollability and its production - Google Patents

Abstract

PURPOSE:To improve the machinability, strength, and corrosion resistance of the title steel by applying two-stage controlled rolling to a steel in which respective contents of C, Si, Mn, S, Ni, Cr, N, Nb, Pb, Bi, rare earth elements, etc., and forming the structure of the above steel into recrystallization working duplex structure. CONSTITUTION:A steel having a composition consisting of, by weight, <=0.03% C, <=2% Si, <=10% Mn, <=0.03% S, 6-20% Ni, 16-30% Cr, 0.1-0.3% N, 0.02-0.25% Nb, 0.03-0.3% Pb and/or 0.03-0.3% Bi, one or more kinds among 0.0005-0.01% B, 0.0005-0.01% Ca, 0.005-0.01% Mg, and 0.0005-0.01% rare earth elements, and the balance Fe is refined. This steel is rough rolled at 1000-1200 deg.C and >=50% draft and then cooled for 10sec-5min. Subsequently, the above steel is rolled at 800-1000 deg.C finish rolling temp. and >=30% draft and then cooled at >=4 deg.C/min cooling rate, by which the structure of the steel is formed into recrystallization working duplex structure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a steel for fi1''?L used in chemical, seawater or atomic couplants, which has excellent controlled rolling properties, high strength and free machinability. of austenitic stainless steel and its 1m method.

[Prior art] Austenitic stainless steel having a double structure structure subjected to controlled rolling and recrystallization is disclosed in Japanese Patent Application Laid-Open No. 63-53244.
As shown in 5US304, it is a material that has both high strength and high corrosion resistance, but due to the high strength, the machinability was inevitably considerably lower than that of 5US304. In order to improve this, a stiffening element such as Pb, S, or Se is usually added to improve the stiffness, and a decrease in hot workability is also prevented by adding B or the like.

However, in the case of high N materials, although it is possible to increase the rigidity by adding Pb-B or the like, it is difficult to improve hot workability. Furthermore, improvements in p and open workability by adding B and the like are effective in the rough rolling temperature range, but sufficient improvements have not yet been made in the controlled rolling temperature range.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems of hot workability in a controlled rolling temperature range of a high-N free-machining austenitic stainless steel. Another object of the present invention is to provide a free-cutting austenitic stainless steel that has improved hot workability in a controlled rolling temperature range while maintaining corrosion resistance, and a method for producing the same.

[Means for Solving the Problems] As a result of extensive research into improving workability in the controlled rolling temperature range of 800 to 100°C, the inventors found that C
Limiting the amount of elements that cause grain boundary embrittlement such as
The present invention was completed based on the new finding that processability is significantly improved due to the combined effect of adding 11 types of 31 types.

The free-cutting austenitic stainless steel with excellent controlled rolling properties of the present invention has a weight ratio of 0.0.03% or less, Si: 2.00% or less, Mn: 10.0% or less, as the first invention.
S; 0, o 30% or less, Ni: 6-20%, Cr
;16-30%, N:0.10-0.30%, Nb, 0
．． 02 to 0.25%, one or two of Pb, 0.03 to 0.30%, and Bi; 0.03 to 0.30%.
? I, 8.0.0005-0.0100%, Ca: 0
, o OO5~0.0100%, Mg; 0.0005
~0.0100% and rare earth elements; O, o OO5~
Contains one type or 2fi or more of 0.0100%,
The gist is that the remainder consists of Fe and its impurity elements, and the second invention further includes Sn; 0.0 to improve machinability.
70% or less, Te; 0.80% or less, Se; 0.80%
Hereinafter, it contains one or more of P, 0.100% or less, Sl); 0.70% or less, and S; 0.080% or less. 2. In order to further improve corrosion resistance, as a third invention, Mo; 4.0% or less and Cu; 1 out of 4.0% or less
Contains one or two species, and a fourth to further improve strength.
As an invention, V: 030% or less, Ti: 0.30% or less,
W, 0.30% or less, Ta; 0.30% or less, Hf, 0
．． 30% or less, Zr; 0.30% or less, and AI, 0.
Containing one or more of 30% or less, O; 0.00 as the seventh invention to further improve hot workability.
The gist of this is to keep it below 50%.

The fifth invention includes the third invention in the second invention, and the sixth invention includes the third invention in the second invention.
The invention includes the third invention and the fourth invention in the second invention, and the eighth invention includes the third invention, the fourth invention, and the seventh invention in the second invention.

In addition, the method for producing free-cutting austenitic stainless steel with excellent controlled rolling properties according to the present invention has a weight ratio of C: 0.03%.
Below, Si: 2.00% or less, Mn: 10.0% or less, S: 0.030% or less, Ni: 6 to 20?6, Cr
:16-30%, N, 0.10-0.30%, Nb, 0
．． 02 to 0.25%, one or two of Pb; 0.03 to 0.30% and Bi; 0.03 to 0.30%.
seeds, B; 0.0005 to 0.0100%, Ca; 0.
0005~0.0100%, Mg: 00005~
0.0100% and rare earth elements; 0.0005-0.
0100%, or contains Mo; 4.0% or less and Cu; IFII or two of 4.0% or less, with the remainder being Fe and its impurity elements. The steel is heated to 1,100 to 1,300°C, and the processing amount is 50 at a rough rolling temperature of 1,000 to 1,200°C.
Rolled at 95 or higher, cooled for 10 seconds to 5 minutes after rough rolling,
Then finish rolling at a temperature of 800 to 1000°C l13
The gist is that rolling is carried out by 0% or more, the cooling rate after rolling is 4°C/min or more, and the structure is made of a recrystallized dual structure structure.

In the present invention, the recrystallized double structure provides high strength, high toughness, and high corrosion resistance to austenitic stainless steel, and by adding appropriate amounts of Pb, Bi, B, etc., and reducing grain boundary embrittlement elements such as C. By limiting the machinability to 5US304
This is based on new knowledge that it also improves controlled rolling properties.

In addition, in the present invention, the controlled rolling property is expressed by the reduction of area in the controlled rolling temperature range, that is, 800 to 1000 ° C.
The target value is 70% or more.

The recrystallized double structure is obtained when an alloy having the composition of the present invention is processed by the manufacturing method of the present invention. Generally, the structure of austenitic stainless steel is
It consists of a microstructure of about 100 μm observed with an optical microscope [11] and a substructure of about 1 μm observed with an electron microscope. Austenitic stainless steel is usually used after solution heat treatment.The structure after solution heat treatment is 2001 in Figure 2 (A) and 20,000 times larger in Figure 2 (Ro). ), and the conventionally known controlled rolling microstructure is shown in Figure 3 (a) and (b), where the microstructure in (a) is a processed structure of mixed grains, and the microstructure in (b) is a processed structure of mixed grains. The sub-structure is also a processed structure. FIG. 1 is a diagram showing the relationship between temperature and time for obtaining a recrystallized double structure structure according to the present invention. First, heating temperature 1100-1300
0 to 1000 to completely dissolve Nb precipitates at ℃
Rough rolling is performed at 1200°C with a processing amount of 50% or more, and the cooling time after ffi rolling is 10 seconds to 5 minutes, and the final roll of rough rolling is quickly cooled to a predetermined temperature and recrystallized before the start of finish rolling. to obtain a fine recrystallized structure. Finish rolling is performed at 800 to 1000°C with a processing amount of 30% or more, and the cooling rate after finish rolling is 4°C/sin or more.

Photographs of microstructures manufactured by the manufacturing methods of the present invention and comparative examples are shown in FIGS. 4 to 8.

Finish rolling start temperature is 1050℃, 980℃, 900℃,
(A) in each photo is 200 at 850℃ and 700℃
Multiply (b) is 20,000 times 0 Recrystallization processing according to the present invention 2
! As is clear from the photographs in FIGS. 5 to 7, the microstructure consists of recrystallized structures of several tens of microns, which in turn consist of sub-recrystallized structures of several microns. The subgrains of this substructure are a processed structure having a high density of dislocations.

Here, if the finish rolling start temperature is made higher than 1000°C,
As shown in FIG. 4, almost no dislocations are seen in the sub-crystal grains, and there is almost no increase in strength.

On the other hand, if the temperature is lower than 800°C, as is clear from FIG. 8, no sub-recrystallized structure is observed, the PM rollability deteriorates, and the toughness and ductility decrease.

In the present invention, in austenitic stainless steel, in order to obtain excellent properties by 1% by the above-mentioned controlled rolling, Pb
According to the composition of the present invention, which is based on the knowledge that it is important to add appropriate amounts of Bi, B, etc. and to lower Cfi, the stiffness is increased by adding Pb, Bi, etc.
In the case of high N materials, the addition of B alone will not improve the hot workability, especially at 800%.
It is not possible to improve controlled rolling properties at ~1000°C. Therefore, by lowering the content of elements that cause grain boundary embrittlement such as C, the influence of high N can be eliminated and controlled rolling properties can be improved. This is what we discovered.

As mentioned above, the suitability of Pb, Bi, B, etc. addition and
Reducing C, etc. is essential for improving the strength of controlled rolled materials, improving controlled rolling properties, and improving stiffness, and stainless steel that has excellent strength and stiffness can only be achieved by combining these elements with controlled rolling. It has been found that steel can be obtained.

The reasons for limiting the composition of the steel of the present invention will be explained below.

C: O, o 3% or less C is an important element in the present invention, which significantly impairs corrosion resistance after controlled rolling and hot workability during controlled rolling, and it must be at least 0.03% or less. There is. Also, when there is a lot of C, Nb(C,N) grows greatly, and (NbCr)
Since it interferes with the fine precipitation of N and causes a decrease in strength and controlled rolling properties, the upper limit should be set at 0.03%.

Si: 2.0% or less Si is an element that is added as a deoxidizing agent and also improves strength, but on the other hand, it is also an element that reduces hot cracking during welding and the amount of N solid solution during solidification. To obtain a good steel ingot 2.
It is necessary to keep the amount below 0%, and the upper limit is set at 2.0%.

Mn: 10.0% or less Mn is an element that is added as a deoxidizing agent and increases the solubility of N, but on the other hand, as the content increases, corrosion resistance and hot workability are impaired, so the upper limit is set at 10.0%. did.

Ni; 6 to 20% Ni is a basic element of austenitic stainless steel, and 6 to 20% is necessary to obtain excellent corrosion resistance and an austenitic structure.
% or more is required. However, if the amount of N increases too much, weld cracking properties during welding, hot workability, etc. will be reduced, so the upper limit was set at 20%.

Cr: 16-30% C is a basic element of stainless steel, and in order to obtain excellent corrosion resistance, it must be contained at least 16%. However, if CrJiL increases too much, δ/γ at high temperatures
Since this would impair the balance of the tissue, the upper limit was set at 30%.

N, 0.10-0.30% N is the most important strengthening element in the present invention, having interstitial solid solution strengthening, grain refinement by (CrNb)N precipitation, and precipitation strengthening effects. It is also an element that contributes to improving corrosion resistance after controlled rolling, and to obtain these effects, it must be contained at 0.10% or more, with a lower limit of 0.10% or more.
It was set at 10%. However, as the N content increases, hot workability decreases and blowholes are more likely to occur during solidification and welding, so the upper limit was set at 0.30%.

Nb: 0.02-0.25% Nb fixes residual C as NbC, improves corrosion resistance after controlled rolling, and refines grains and improves strength after controlled rolling by (CrNb)N precipitation. In the present invention, it is a main element and must be contained in an amount of at least 0.02%. However, Nb is also an expensive element, and if it is included more than necessary, it impairs hot workability, so the upper limit was set at 0.25%.

Mo: 4.0% or less, Cu: 4.0% or less Both Mo and Cu are elements that further improve the corrosion resistance of the steel of the present invention. However, Mo and Cu are also expensive elements, and
If the content exceeds 2≦, hot workability will be impaired, so the upper limit was set at 4% for each.

S, 0.030% or less S is an element that improves corrosion resistance by significantly reducing its content, and also improves ductility and toughness (especially in the direction perpendicular to rolling) after controlled rolling. The upper limit was set at 0.030%.

Bi: 0.03-0.30%, Pb: 0.03-0.3
0Bi and Pb are elements necessary to improve machinability, and in order to obtain the above effect, it is necessary to add at least 0.03% or more of Pb and Bi. but,
If both Bi and Pb exceed 0.30%, hot workability and υffj'j rollability are inhibited, so the upper limit was set at 0.30%.

B・0.0005-0.0100% B is an element necessary to improve hot workability,
At least 0.0005 to improve hot workability
It is necessary to add more than %. However, even if added in excess of 0.0100%, no improvement in the effect is expected, so the upper limit was set at 0.0100%.

Se; 0.80% or less, s; 0, Os o%% or less Sn; 0.70% or less, Te; 0.80% or less, p; o
, t.

0% or less, Sb, 0.70% or less S, Se, Sn, P, Te and sb are elements that improve the machinability of the steel of the present invention, S exceeds 0.020%,
It is necessary to contain Se at 0.005% or more. However, S, Se and Te both exceed 0.080%,
Also, P is o, xoopr is Sn and sb is 0.70%
Since hot workability, controlled rolling properties, and corrosion resistance will decrease if the content exceeds o, osopg,
0100% and 0.70%.

V, Ti, W, Ta, )
If, Zr, Al; 0.30% or less; Ti, W, Ta, Hf, Zr, and AI are elements added to improve strength, but they must not be contained in amounts exceeding 0.30%. Since no improvement in the effect can be expected, the upper limit was set at 0.30%.

Ca; 0.0005-0.0100%, Mg; 0.00
05-0.0100%, rare earth elements; o, o OO5
~0.0100% Ca, Mg, and rare earth elements are necessary elements to improve hot workability, and in order to improve hot workability, it is necessary to add at least 0.0005% or more. .

However, since no improvement in the effect can be expected even if 0.0100% or more is added, the upper limit was set at 0.0100%.

0.0.0050% or less 0 is an element that causes grain boundary embrittlement, and in order to improve hot workability and controlled rolling properties, it should be limited to a low grade, and the upper limit was set as 0.0050%. .

In addition, in controlled rolling, the heating temperature is set to 1100 to 130.
The reason for setting the temperature to 0°C is to reduce the deformation resistance during rolling and to sufficiently dissolve Nb precipitates in the steel. 1
This is because the deformation resistance is large at temperatures below 100°C, and it is difficult to completely dissolve Nb precipitates.
This is because heating above 0° C. melts some of the grain boundaries or coarsens the crystal grains, making rolling difficult.

The reason why the rough rolling temperature was set to 1000 to 1200°C is to obtain a fine recrystallized structure, and it is not possible to obtain a fine recrystallized structure below 1000°C.
This is because the crystal grains become coarser due to recrystallization.

Processing 1 made the processing amount more than 50% in rough rolling.
This is because when t is less than 50%, the energy of lattice defects is small and a fine structure cannot be obtained.

The reason why the finish rolling temperature was set to 800 to 1000°C is to obtain a recrystallized double structure structure. This is because if it is below 800°C, it becomes a processed structure and it is not possible to obtain a recrystallized double structure structure, and if it exceeds 1000°C, it becomes a recrystallized structure due to recrystallization.
was set as the upper limit.

In finish rolling, the processing amount was 30% or more.
% or less, the processing strain is small and a recrystallized double structure cannot be obtained.

The reason why cooling is performed for 10 seconds to 5 minutes after rough rolling is because it is the time required to cause recrystallization after rough rolling. In addition, the cooling rate after finish rolling was set to 4°C/min or more because slow cooling at 4°C/min or less was used for Cr2aCs or Crz
This is because N precipitates at grain boundaries and reduces corrosion resistance.

[Example] Next, the characteristics of the steel of the present invention and its manufacturing method will be clarified by comparing it with conventional steel and comparative steel through examples.

Table 1 shows the chemical composition (ffi amount %) of these test steels.The test steels in Table 1 were subjected to controlled rolling according to the method of the present invention, and the strength, pitting potential, reduction in the controlled rolling temperature range,
The machinability and hot workability were measured and the results were
It was shown to. In addition, Table 3 shows the structure, strength, pitting potential, reduction in the controlled rolling temperature range, intergranular corrosion resistance, machinability, Measurements of thermal In processability are shown.

Regarding the structure, the structure was observed using an optical microscope after performing 10% f@ acid electrolytic etching. Also,
After preparing the thin film, the electron microscopic structure was observed using a transmission electron dark microscope.

Regarding strength, yield strength elongation was measured using a JIS No. 4 test piece.

Regarding controlled rolling properties, 900
A high-speed, high-temperature tensile test was conducted at a temperature of 50 a+m/sec at a tensile speed of 50 a+m/sec, and the aperture value was measured.

Corrosion resistance was measured by measuring pitting potential in a 3.5% NaCl aqueous solution at 30°C.

Regarding machinability, a 20 mm test piece was subjected to a drill life test using an S K H9 51φ drill at a rotation speed of 792 rpm, a feed rate of 0, and 10 mts/rev.

The results were shown.

Hot workability was determined by blooming at 1100° C. and the presence or absence of intergranular cracking.

(Left below) As is known from Tables 1 and 2, No. 1
-5 are steels with the composition of the first invention steel subjected to controlled rolling by the method of the invention, and the results were satisfactory in terms of strength, pitting potential, reduction of area in the controlled rolling temperature range, machinability, and hot workability. I got it.

No. 6 to 11 contain Se, Te, and S to improve machinability.
, P, and Sb were added to the composition of the second invention steel of the present invention, which was subjected to controlled rolling by the method of the present invention, and a recrystallized double structure structure was obtained, and strength, pitting corrosion, and control were obtained. Excellent results were obtained in terms of reduction of area at rolling temperature, hot workability, and machinability.

No. 12 to 14 contain Mo and C to improve corrosion resistance.
The third invention steel of the present invention containing u was subjected to controlled rolling according to the method of the present invention, but the recrystallized double structure J11
m, and excellent results were obtained in terms of strength, pitting potential, reduction of area at controlled rolling temperature, hot workability, and machinability. In particular, it was confirmed that the material was excellent in terms of pitting potential and corrosion resistance.

No. 15 to 22 are ■, TiW, T to improve strength.
Although it is the fifth invention steel with the addition of a, Hf, Zr, and AI,
Controlled rolling according to the method of the present invention resulted in a recrystallized double-structure structure, and excellent results were obtained in strength, pitting potential, reduction in area at controlled rolling temperature, machinability, and hot workability. It was confirmed that an excellent result of 86 kgf/1III2 could be obtained.

Nos. 23 to 27 are the fifth invention steels of the present invention with further improved machinability and corrosion resistance, Nos. 28 to 33 are the sixth invention steels with further improved machinability, corrosion resistance and strength, No. 3
4 to 35 are the seventh invention steels in which the amount of O was regulated to improve the reduction in controlled rolling and hot workability, and No. 36 to 37 are the reduction in machinability, corrosion resistance, strength, hot workability, and control rolling temperature. These are the 8th invention steels with improved properties, but in all cases, a double-structure structure was obtained by recrystallization, and excellent results were obtained in terms of strength, pitting potential, reduction of area at controlled rolling temperature, hot workability, and machinability. .

Nos. 38 to 43 are comparative examples having components outside the composition range of the steel of the present invention, and were subjected to controlled rolling according to the method of the present invention. sex,
Poor drawing at controlled rolling temperature. No. 39 has less N1 and C than the composition range, but the pitting corrosion potential is inferior. No. 40 has N in the composition box [contains less than 1 fl, but strength and pitting are poor. Poor eclipse potential. No. 41 is Nb
However, the strength and pitting potential are inferior. No. 42 contains Pb and B below the composition range, and No. 43 contains no Pb or B at all, but is inferior in machinability and hot workability. Also, no.

・14 is a conventional steel equivalent to 5US304N2,
Poor machinability.

Table 3 shows the first invention steel and second invention steel in Table 1 processed by the method of the invention and by a method other than the method of the invention.

No. 5, where the finish rolling temperature is high < 1050 ° C., only a recrystallized structure is obtained, and the strength is low, and the finish rolling temperature is low. 7
No. 6, which is 00° C., can only obtain a processed structure and is inferior in machinability. No. 7 was subjected to solution heat treatment after rolling and was inferior in strength. No. 8 was subjected to one stage of controlled rolling at 900°C and is a textured texture with extremely high anisotropy. No. 9 was subjected to one stage of controlled rolling at 700°C and is a textured texture. Poor elongation and anisotropy. No. 10 has a cooling rate of 3°C/min after finish rolling, and is inferior in pitting potential.

No. 11 has a low processing rate of 10% in finish rolling, but sufficient strength is not obtained.

Nos. 1 to 4 are the steels of the first invention subjected to controlled rolling using the method of the present invention, but due to the controlled rolling using the method of the present invention, a recrystallized double structure structure is formed, and the strength, hole tL'': r, position,
Both reduction of area, machinability, and hot workability at controlled rolling temperature are f.
I got a good result.

[Effects of the Invention] As explained above, the free-cutting austenitic stainless steel with excellent controlled rolling properties and the method for producing the same according to the present invention include adding B to the austenitic stainless steel and adding C and O!
In addition to lowering L, appropriate amounts of N and Nb are added, and the structure is recrystallized to a double structure structure by two-step controlled rolling. Free-cutting elements are added to maintain the free-cutting properties of austenitic stainless steel. The free-cutting austenitic stainless steel with controlled rolling properties of the present invention, which has significantly improved controlled rolling properties by adding an appropriate amount, has the strength required as a structural material used in chemical, seawater, and atomic applications.
It satisfies all the characteristics of corrosion resistance, hot workability, machinability, and controlled rolling properties, and is extremely useful as a corrosion-resistant, free-cutting structural material.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between temperature and time in the controlled rolling process according to the method of the present invention, and Figures 2 (a) and (b) are photographs of closed microchains showing the recrystallized structure after solution heat treatment. Reproduction diagrams, Figures 3 (a) and (b) are reproduction diagrams of got mirror photographs showing the processed structure after finish rolling at 900°C, and Figures 4 (a) and (b) are recrystallization diagrams at a finishing rolling start temperature of 1050°C. Figures 5 (a) and 5 (b) are copies of micrographs showing a double structure, and Figure 6 (a) are copies of rsm mirror photographs showing a double structure after recrystallization at a finishing rolling start temperature of 980°C. (b) is a replica of the W4 microphotograph showing the recrystallized double structure structure at a finish rolling start temperature of 900°C, and Figures 7 (a) and (b) are a finish rolling start temperature of 85°C.
Figures 8 (a) and 8 (b) are copies of micrographs showing the double-structured structure after recrystallization at 0°C, when the finish rolling start temperature is 700°C.
FIG. 2 is a replica of a microscopic photograph showing a processed double structure of FIG. Figure 2 (a) (b) Figure (a) (b) Method of writing procedural amendments) 1. Display of the case 1988 Patent application No. 248566 2, Title of the invention: Free-cutting austenitic stainless steel with excellent controlled rolling properties and its manufacturing method 3, Person making the amendment Relationship with the case Patent applicant address: Tokai, Aichi Prefecture 1-4 Wanowari, Arao-cho, Ichi, Agent: 450 Address: 2nd Floor, Tamama Building, 3-3-4 Meieki, Nakamura-ku, Nagoya (052) 583-9720 December 7, 1988 (Shipping date: Showa) December 20, 1963) 6. Subject of amendment Figure 1

Claims (10)

[Claims] (1) C: 0.03% or less, Si: 2.00% by weight
Hereinafter, Mn: 10.0% or less, S: 0.030% or less,
Ni: 6-20%, Cr: 16-30%, N: 0.10
~0.30%, Nb; 0.02-0.25%, Pb;
0.03-0.30% and Bi; 0.03-0.30
1 or 2 of % and B; 0.0005 to 0.0
100%, Ca; 0.0005-0.0100%, Mg
;0.0005-0.0100% and rare earth elements;0
．． 0005 to 0.0100%, the remainder consists of Fe and its impurity elements,
A free-cutting austenitic stainless steel with excellent controlled rolling properties, characterized in that its structure consists of a processed double structure structure. (2) C: 0.03% or less, Si: 2.00% by weight
Below, Mn: 10.0% or less, Ni: 6 to 20%, Cr
;16-30%, N;0.10-0.30%, Nb;0
．． 02 to 0.25%, one or two of Pb; 0.03 to 0.30% and Bi; 0.03 to 0.30%, B; 0.0005 to 0.0100%, Ca ;0.0
005-0.0100%, Mg; 0.0005-0.0
100%, and rare earth elements; 0.0005-0.01
One or more of 00% and Sn; 0.70%
Hereinafter, Te; 0.80% or less, Se; 0.80% or less,
P; 0.100% or less, Sb; 0.70% or less and S
; Contains one or more of 0.080% or less, the remainder consists of Fe and its impurity elements, and has an excellent controlled rolling property characterized by having a worked double structure structure. Free-cutting austenitic stainless steel. (3) C: 0.03% or less, Si: 2.00% by weight
Hereinafter, Mn: 10.0% or less, S: 0.030% or less,
Ni: 6-20%, Cr: 16-30%, N: 0.10
~0.30%, Nb; 0.02-0.25%, Pb;
0.03-0.30% and Bi; 0.03-0030
1 or 2 of % and B; 0.0005 to 0.0
100%, Ca; 0.0005-0.0100%, Mg
;0.0005-0.0100%, and rare earth elements:
Contains one or more of 0.0005 to 0.0100%, one or two of Mo: 4.0% or less and Cu: 4.0% or less, with the remainder being Fe and its impurities. A free-cutting austenitic stainless steel with excellent controlled rolling properties, characterized by its structure consisting of a processed double structure structure. (4) C: 0.03% or less, Si: 2.00% by weight
Hereinafter, Mn: 10.0% or less, S: 0.030% or less,
Ni: 6-20%, Cr: 16-30%, N: 0.10
~0.30%, Nb; 0.02-0.25%, Pb;
0.03-0.30% and Bi; 0.03-0.30
1 or 2 of % and B; 0.0005 to 0.0
100%, Ca; 0.0005-0.0100%, Mg
;0.0005-0.0100%, and rare earth elements;
One or more of 0.0005 to 0.0100%, V: 0.30% or less, Ti: 0.30% or less, W
; 0.30% or less, Ta; 0.30% or less, Hf; 0.
30% or less, Zr; 0.30% or less and Al; 0.3
Contains one or more of 0% or less, with the remainder being F.
A free-cutting austenitic stainless steel with excellent controlled rolling properties, which is composed of E and its impurity elements and whose structure is a worked double structure structure. (5) C: 0.03% or less, Si: 2.00% by weight
Below, Mn: 10.0% or less, Ni: 6 to 20%, Cr
;16-30%, N;0.10-0.30%, Nb;0
．． 02 to 0.25%, one or two of Pb; 0.03 to 0.30% and Bi; 0.03 to 0.30%, B; 0.0005 to 0.0100%, Ca ;0.0
005-0.0100%, Mg; 0.0005-0.0
100%, and rare earth elements; 0.0005-0.01
One or more of 00% and Sn; 0.70%
Hereinafter, Te; 0.80% or less, Se; 0.80% or less,
P; 0.100% or less, Sb; 0.70% or less and S
; 0.080% or less of one or more of the following; and Mo
4.0% or less and Cu; 4.0% or less, the remainder is Fe and its impurity elements, and the structure is a processed double structure structure. Free-cutting austenitic stainless steel with excellent controlled rolling properties. (6) C: 0.03% or less, Si: 2.00% by weight
Below, Mn: 10.0% or less, Ni: 6 to 20%, Cr
;16-30%, N;0.10-0.30%, Nb;0
．． 02 to 0.25%, one or two of Pb; 0.03 to 0.30% and Bi; 0.03 to 0.30%, B; 0.0005 to 0.0100%, Ca ;0.0
005-0.0100%, Mg; 0.0005-0.0
100%, and rare earth elements; 0.0005-0.01
One or more of 00% and Sn; 0.70%
Hereinafter, Te; 0.80% or less, Se; 0.80% or less,
P; 0.100% or less, Sb; 0.70% or less and S
; 0.080% or less of one or more of the following; and Mo
; 4.0% or less and Cu; one or two of 4.0% or less; V; 0.30% or less; Ti; 0.30% or less; W; 0.30% or less; Ta; 0 .30% or less, Hf
0.30% or less, Zr; 0.30% or less and Al;
A comfortable material with excellent controlled rolling properties, characterized by containing one or more of 0.30% or less, the remainder consisting of Fe and its impurity elements, and having a textured double structure structure. Machined austenitic stainless steel. (7) C: 0.03% or less, Si: 2.00% by weight
Hereinafter, Mn: 10.0% or less, S: 0.030% or less,
Ni: 6-20%, Cr: 16-30%, N: 0.10
~0.30%, Nb; 0.02-0.25%, O; 0.
0050% or less, and one or two of Pb; 0.03 to 0.30% and Bi; 0.03 to 0.30%,
B; 0.0005-0.0100%, Ca; 0.000
5-0.0100%, Mg; 0.0005-0.010
0%, and rare earth elements; 0.0005-0.0100
Free-cutting austenitic stainless steel with excellent controlled rolling properties, characterized by containing one or more of the following: %, the remainder consisting of Fe and its impurity elements, and having a worked double structure structure. steel. (8) C: 0.03% or less, Si: 2.00% by weight
Below, Mn: 10.0% or less, Ni: 6 to 20%, Cr
;16-30%, N;0.10-0.30%, Nb;0
．． 02-0.25%, O; 0.0050% or less, Pb
;0.03-0.30% and Bi;0.03-0.3
1 or 2 of 0% and B; 0.0005 to 0.
0100%, Ca; 0.0005-0.0100%, M
g; 0.0005 to 0.0100%, and one or more of rare earth elements; 0.0005 to 0.0100%, Sn; 0.70% or less, Te; 0.80% or less, Se: 0.80% or less, P: 0.100% or less, Sb
; 0.70% or less and S; 1 out of 0.080% or less
species or two or more species, Mo; 4.0% or less and Cu;
One or two of 4.0% or less and V; 0.30%
Below, Ti: 0.30% or less, W: 0.30% or less, T
a; 0.30% or less, Hf; 0.30% or less, Zr; 0
．． 30% or less and Al; 0.30% or less, the remainder is Fe and its impurity elements, and the structure is a processed double structure structure. Free-cutting austenitic stainless steel with excellent rolling properties. (9) C: 0.03% or less, Si: 2.00% by weight
Hereinafter, Mn: 10.0% or less, S: 0.030% or less,
Ni: 6-20%, Cr: 16-30%, N: 0.10
~0.30%, Nb; 0.02-0.25%, Pb;
0.03-0.30% and Bi; 0.03-0.30
1 or 2 of % and B; 0.0005 to 0.0
100%, Ca; 0.0005-0.0100%, Mg
;0.0005-0.0100% and rare earth elements;0
．． A steel containing one or more of 0005 to 0.0100%, with the remainder consisting of Fe and other impurity elements, was heated to 1100 to 1300°C, and the rough rolling temperature was 1000°C.
Rolling with a processing amount of 50% or more is performed at ~1200°C, cooling for 10 seconds to 5 minutes after rough rolling, and then finishing at a temperature of 800~1
Excellent controlled rolling properties characterized by rolling at 000°C with a working amount of 30% or more, cooling at a cooling rate of 4°C/min or more after rolling, and having a structure consisting of a recrystallized dual structure structure. A method for producing free-cutting austenitic stainless steel. (10) Weight ratio: C: 0.03% or less, Si: 2.00
% or less, Mn; 10.0% or less, S; 0.030% or less, Ni; 6 to 20%, Cr; 16 to 30%, N; 0.1
~0.30%, Nb; 0.02-0.25%, Pb;
0.03-0.30% and Bi; 0.03-0.30
1 or 2 of % and B; 0.0005 to 0.0
100%, Ca; 0.0005-0.0100%, Mg
;0.0005-0.0100%, and rare earth elements;
Contains one or more of 0.0005 to 0.0100%, one or two of Mo: 4.0% or less and Cu: 4.0% or less, with the remainder being Fe and its impurities. Heating steel consisting of elements to 1100-1300℃,
Rolling is performed at a rough rolling temperature of 1000 to 1200°C with a working amount of 50% or more, cooling for 10 seconds to 5 minutes after rough rolling, and then rolling is performed at a finishing rolling temperature of 800 to 1000°C with a working amount of 30% or more, and after rolling. A method for producing a free-cutting austenitic stainless steel having excellent controlled rolling properties, characterized in that the cooling rate is 4° C./min or more, and the structure is composed of a recrystallized double structure structure.