JP4906193B2 - Ferritic free-cutting stainless steel - Google Patents

Description

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【発明の効果】
本発明によれば、フェライト系Ｓ快削ステンレス鋼において、Ｓｎに加えてＢｉ，Ｃｕ等を添加し、更には介在物の形態を制御することによって、環境衛生上で問題のあるＰｂ，Ｓｅ，Ｔｅなしに被削性，熱間製造性，冷間鍛造性，製造歩留・製造コストに優れたフェライト系快削ステンレス鋼を安価に得ることができる。
【図面の簡単な説明】
【図１】 １８％Ｃｒ―０．０２％Ｃ−０．０２％Ｎ系のステンレス材料（４ｍｍ厚さ）のドリル穴開け時間とＳｎ量の関係を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ferritic stainless steel excellent in machinability and cold workability, and is an environment-friendly ferritic free-cutting stainless that does not contain a highly toxic element such as Pb, Se, Te as a free-cutting element. It is about steel.
[0002]
[Prior art]
Conventionally, ferritic S free-cutting stainless steel represented by SUS430F has a drawback that it has low cutting resistance but is inferior in chip disposal. In addition, deterioration of corrosion resistance due to sulfides, generation of hydrogen sulfide and low cold workability have been problems.
In recent years, steels to which free cutting elements such as Pb, Te, Se and the like are added have been proposed and put into practical use in order to solve these problems in recent years by reducing Mn and lowering the ratio of MnS to increase corrosion resistance (see, for example, 10-237603). However, these highly toxic free-cutting elements such as Pb are becoming increasingly regulated due to environmental problems in recent years, and are becoming impossible to manufacture.
[0003]
In the United States, a composite free-cutting steel of Sn, Cu, S has been proposed as an alternative to Pb free-cutting steel (carbon steel) (Patent USP-5961747).
Further, since Bi does not have toxicity and does not generate corrosive gas, Bi-containing stainless steel is regarded as promising as an environment-friendly free-cutting stainless steel (for example, Japanese Patent Publication No. 5-45661).
[0004]
However, super free-cutting elements such as Bi and Pb not only significantly reduce the hot productivity, but are also hardly soluble elements, so the addition yield of Bi and Pb is low due to segregation and sedimentation, etc. The product yield is poor and the cost is increased because large granular Bi and Pb are generated in the product.
Thus, in conventional steel, an inexpensive ferritic free-cutting stainless steel excellent in environmental friendliness that combines machinability, cold workability, and manufacturability without using a highly toxic element such as Pb. Not proposed.
[0005]
[Problems to be solved by the invention]
The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and without using a toxic element such as Pb, hot workability, machinability and cold workability. The objective is to provide a ferritic S free-cutting steel with good quality and environmental friendliness at low cost.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors use Sn, which is difficult to reduce hot manufacturability and cold forgeability, as a free-cutting element of ferritic stainless steel, and furthermore, combined addition of Bi and Cu, etc. As a result, machinability and cold workability are improved, the solubility of Bi is increased, the productivity is remarkably increased, and the machinability is further improved by controlling the amount of Si, O, Ca, and Al. The present invention has been found out and the present invention has been made.
[0007]
The gist of the present invention is as follows.
(1) In mass%,
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0%, S: 0.005-0.05%,
Cu: 0.2 to 0.7%, Si: 0.05 to 0.5%,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities.
(2) By mass%
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0% S: 0.05-0.4%
Cu: 0.2 to 0.7%, Si: 0.05 to 0.5%,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities.
( 3 ) In mass%,
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0%, S: 0.005-0.05%,
Cu: 0.5 to 2.5%, Si: 0.05 to 0.5%,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%, Bi: 0.01-0.15%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities.
( 4 ) In mass%,
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0%, S: 0.05-0.4%,
Cu: 0.5 to 2.5%, Si: 0.05 to 0.5%,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%, Bi: 0.01-0.15%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities.
( 5 ) In mass%,
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0%, S: 0.005-0.05%,
Cu: 0.5 to 2.5%, Si: 0.05 to 0.5%,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%, Bi: 0.01-0.15%,
and,
Mg: 0.0005-0.05%, Ag: 0.02-0.15%
A ferritic free-cutting stainless steel comprising at least one of the above, and the balance being Fe and inevitable impurities.
( 6 ) In mass%,
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0%, S: 0.05-0.4%,
Cu: 0.5 to 2.5%, Si: 0.05 to 0.5%,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%, Bi: 0.01-0.15%,
and,
Mg: 0.0005-0.05%, Ag: 0.02-0.15%
A ferritic free-cutting stainless steel comprising at least one of the above, and the balance being Fe and inevitable impurities.
( 7 ) In mass%,
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0%, S: 0.005-0.05%,
Cu: 0.2-0.9%, Si : 0.05-0.5 %,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
and,
B: 0.0005 to 0.02%,
Ca: Ferritic free-cutting stainless steel containing at least one of 0.0005 to 0.02%, and remaining balance Fe and inevitable impurities.
( 8 ) In mass%,
C: 0.08% or less, Mn: 0.05-3.0%,
P: 0.01 to 0.1%, Cr: 15 to 22%,
Sn: 0.03-0.3%, N: 0.08% or less,
Ni: 0.05-1.0%, S: 0.05-0.4%,
Cu: 0.2-0.9%, Si : 0.05-0.5 %,
Al: 0.015% or less, Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
and,
B: 0.0005 to 0.02%,
Ca: Ferritic free-cutting stainless steel containing at least one of 0.0005 to 0.02%, and remaining balance Fe and inevitable impurities.
( 9 ) The ferritic free-cutting stainless steel according to (1) or (2) above, further containing Zr: 0.005 to 0.3% by mass%.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The reasons for limiting the component ranges of the steel of the present invention according to claims 1 and 2 will be described below.
C increases the strength of the matrix and degrades the corrosion resistance, cold forgeability, and machinability, so the upper limit was made 0.08%. In order to improve the surface properties after cutting, the content is preferably 0.04% or less.
[0009]
Mn is an element that produces S and sulfides and improves the machinability, so 0.05% or more is added. However, if added over 3%, the effect is saturated, and conversely, machinability and cold workability deteriorate. Therefore, the upper limit was made 3.0%. Further, since Mn is an element that deteriorates corrosion resistance and outgas resistance, in order to improve them, it is preferably 0.5% or less.
[0010]
P is an element effective for improving machinability, and is added by 0.01% or more. However, if added in a large amount, hot manufacturability, cold forgeability and corrosion resistance are deteriorated, so the upper limit was made 0.1%. Preferably they are 0.02% or more and 0.05% or less.
[0011]
Cr is added in an amount of 15% or more to ensure corrosion resistance. However, if it exceeds 22%, the productivity is remarkably lowered and the economy is inferior. Therefore, the upper limit was made 22%. Preferably they are 16% or more and 20% or less.
[0012]
Sn is an element that dissolves at high temperatures in ferritic stainless steel and segregates at grain boundaries at low temperatures, and improves machinability without deteriorating hot manufacturability, cold forgeability, and corrosion resistance. It is also an element that improves the solubility of Bi. Therefore, 0.03% or more is added. However, if added over 0.3%, not only the hot productivity deteriorates, but the material becomes hard and the machinability deteriorates. Therefore, the upper limit was made 0.3%.
FIG. 1 shows the drilling time of a material (4 mm thickness) obtained by adding Sn to a 18% Cr-0.02% C-0.02% N-based material. When Sn is 0.03 to 0.3%, the drill penetrates within 20 seconds, and the effect is great. Preferably they are 0.05% or more and 0.2% or less.
[0013]
N increases the strength of the matrix and degrades the corrosion resistance, cold forgeability and machinability, so the upper limit was made 0.08%. In order to improve the surface properties after cutting, the content is preferably 0.03% or less.
Ni is added in an amount of 0.05% or more in order to increase the toughness of the matrix. However, if excessively added, the martensite structure precipitates and deteriorates machinability and cold forgeability, so the upper limit is 1.0%. did. Preferably it is 0.6 or less.
[0014]
S is a free-cutting element which forms Mn and Cr sulfides in the matrix and is added in an amount of 0.005% or more in order to improve machinability. On the other hand, if added excessively, the cold forgeability deteriorates due to the notch effect. Therefore, the upper limit when carrying out cold forging (Claim 1 ) is set to 0.05%. Preferably it is 0.03% or less.
Further, when cold forging is not performed and the machinability is important (Claim 2 ), 0.05% or more of S is added. However, when it exceeds 0.4%, hot workability is also deteriorated. Therefore, the upper limit was made 0.4%. Preferably they are 0.15% or more and 0.35% or less.
[0015]
Cu is a machinable element and has corrosion resistance. As shown in Table 1, 0.2 to 0.7% is contained. Moreover, the vapor pressure of Bi in molten steel is lowered to promote the dissolution of Bi, and the product yield is remarkably improved. Therefore, 0.5% or more is added together with Bi. However, if added over 2.5%, the matrix hardens and deteriorates machinability as well as hot manufacturability. Therefore, the upper limit was made 2.5%. In consideration of Bi yield, machinability and hot manufacturability, it is preferably 1.0% or more and 2.0% or less.
[0016]
Since Si is necessary as a deoxidizing element, 0.05% or more is added. However, if added over 0.5 %, the deoxidized product at the time of solidification becomes a low melting point MnO-SiO ₂ system, and the sulfide crystallized using it as a nucleus is finely dispersed. If it is 0.5 % or less, the deoxidation product at the time of solidification becomes a relatively high melting point and coarse MnO—Cr ₂ O ₃ system rich, and as a result, the sulfide that crystallizes using it as a nucleus is also coarsely dispersed. The machinability is improved. Therefore, it is limited to 0.5 % or less. As will be described later, the coarse dispersion of sulfides requires O of 0.003 % or more. Preferably it is 0.25% or less.
[0017]
When Al is added in an amount exceeding 0.015 %, a hard Al-based oxide is mainly formed to deteriorate the machinability. Therefore, the upper limit is limited to 0.015 %. Preferably it is 0.005% or less.
[0018]
Mo is added in an amount of 0.01 % or more in order to improve the corrosion resistance of the steel, but if added excessively, it is not economical and deteriorates machinability and cold forgeability. Therefore, the upper limit was made 3.0%. Preferably it is 2.5% or less.
[0019]
As described above, O is added in an amount of 0.003 % or more in order to improve machinability by making the deoxidation product during solidification into a coarse MnO—Cr ₂ O ₃ system. However, if added over 0.015%, the ratio of hard oxide increases, and the machinability deteriorates. Therefore, the upper limit was made 0.015%.
[0020]
Next, the reasons for limiting the components of the present invention of claims 3 to 6 will be described.
Bi is added in an amount of 0.01% or more as necessary to further improve the machinability. However, addition over 0.15% not only degrades hot workability, but also causes Bi to settle, resulting in a decrease in product yield and an increase in manufacturing cost. Therefore, the upper limit was made 0.15%. Preferably it is 0.12% or less.
[0021]
Mg is a machinable element and lowers the vapor pressure of Bi in the molten steel to promote the dissolution of Bi, thereby significantly improving the product yield. Therefore, 0.0005% or more is added together with Bi. However, if it exceeds 0.05%, coarse hard inclusions are generated, and machinability and cold workability are deteriorated. Therefore, the upper limit was made 0.05%. In consideration of Bi yield and machinability, it is preferably 0.005% or more and 0.03% or less.
[0022]
Ag is a machinable element and lowers the vapor pressure of Bi in the molten steel to promote the dissolution of Bi, thereby significantly improving the product yield. Therefore, 0.02% or more is added together with Bi. However, if it exceeds 0.15 %, not only the hot workability is deteriorated but also the product yield is deteriorated. Therefore, the upper limit was made 0.15%. Considering Bi yield and machinability, it is preferably 0.05% or more and 0.10% or less.
[0023]
Next, the reasons for limiting the components of the present invention of claim 9 will be described.
Zr improves the machinability and cold forgeability by uniformly finely dispersing sulfides in addition to the formation of carbonitrides. For this reason, 0.005% or more is added as necessary, but excessive addition increases the strength and degrades machinability and cold forgeability. Therefore, the upper limit was made 0.3%. Preferably it is 0.15% or less.
[0024]
Next, the reasons for limiting the components of the present invention of claims 7 and 8 will be described.
B is added in an amount of 0.0005% as necessary to improve hot workability. However, if added over 0.02%, coarse boride is produced, and conversely, hot workability and corrosion resistance are deteriorated. Therefore, the upper limit was made 0.02%. Preferably it is 0.01% or less.
[0025]
Ca is added in an amount of 0.0005% or more as necessary for the purpose of uniformly dispersing the form of sulfide during solidification, improving machinability and hot manufacturability, and improving the corrosion resistance of S free-cutting steel. To do. However, if added over 0.02%, the effect is saturated, and conversely, coarse inclusions increase and the corrosion resistance deteriorates, which is uneconomical. Therefore, the upper limit was made 0.02%. Preferably it is 0.008% or less.
In addition, when adding the said B and Ca, as described in Table 1 (invention steel 28, 29) of an Example, Cu content is made into 0.8 to 0.9%, Table 5 The effect as shown in can be obtained.
[0026]
Delete [0027]
Delete [0028]
Delete [0029]
Delete [0030]
【Example】
Test materials having chemical components shown in Table 1, Table 2, and Table 3 were vacuum-melted to prepare 50 kg steel ingots. Tables 1 and 2 show chemical components when S is less than 0.05% and cold forging and machinability are required. Table 3 shows chemical components when S is 0.05% and more and only machinability is required. Indicates. These steel ingots were hot forged and hot rolled into 21 mmφ bar steel. Thereafter, annealing was performed at 850 ° C., and a 20 mmφ bar wire was finished by cold drawing and centerless processing.
In Table 1, the steel No. 1, 9, 10, 20-27, 30-33, and steel No. 1 in Table 3. 59 and 60 are reference steels.
[0031]
The evaluation was divided into a case where S is less than 0.05% and both cold forgeability and machinability are required, and a case where S is 0.05% and more and only machinability is required.
When both cold forgeability and machinability characteristics are required, that is, when S is less than 0.05% (components: Tables 1 and 2), the machinability, hot workability, and cold forgeability are evaluated. did. Moreover, the state of macro segregation of Sn, S, Bi elements in each part of the steel bar was evaluated as an index of segregation occurring in the melting / solidification process, that is, production yield and production cost.
[0032]
As for machinability, a cutting test was performed on the steel bar under the conditions shown in Table 4 to evaluate machinability. The machinability was evaluated based on the tool life and the chip shape. The tool life was evaluated by the amount of flank wear, and the tool life was evaluated as ○ when the flank wear amount after 30 min was 50 μm or less, and × when it was over 50 μm. In addition, the chip shape was evaluated as “◯” when it was regularly divided into curls, and “X” when the chip was irregularly shaped.
The tool life and chip disposal of the steel of the present invention were both good.
[0033]
As for the hot productivity, a test piece (φ8 mm × 110 mm) was cut out from the slab surface layer, and the hot workability was evaluated by a thermorester test. The evaluation was performed at the breaking drawing value at 1000 ° C., and when the drawing value at that time was 60% or more, the hot workability was judged as “good”. The hot workability of the steel of the present invention was all good.
[0034]
The cold forgeability was evaluated by compressing a 10 mm × 20 mm test piece with a 0.5 mmV notch from the above steel bar, performing a compression test at a speed of 1 mm / sec, and generating cracks (limit compression rate). . When the limit compression ratio was 65% or more, the cold workability was evaluated as ◯, and when it was less than 65%, it was evaluated as x.
All the cold workability of this invention was (circle).
[0035]
The segregation of the bar steel was evaluated from the ratio of the analysis values of Sn, S, Bi free cutting elements by collecting chips for component analysis from the top and bottom of the bar steel. If the analysis value of the element of the bottom Sn, S, Bi is less than 1.3 times the value of the top part (segregation value), the evaluation of segregation is good (good), and if it is 1.3 times or more, segregation. Was evaluated as x (defect). That is, if it was x, it was judged that the production yield was bad and the production cost was high.
All the evaluations of segregation of the present invention were ○.
[0036]
These test results are shown in Tables 5 and 6.
Invention Steel No. 2-8 , 11-19 , 28 and 29 are ferritic stainless steel by adding Bi, Cu, etc. in addition to Sn, cutting ability and hot production without using toxic elements such as Pb , Cold forgeability and segregation (production yield) are all excellent.
In Table 5, steel No. Reference numerals 1, 9, 10, 20 to 27, and 30 to 33 are reference steels.
[0037]
On the other hand, comparative steel No. In 34 to 58, the following defects were observed.
No. of comparative steel. In 34 to 36, since the C amount (%), N amount (%), and Mn amount (%) are high, the material becomes hard, not only the tool life and cold forgeability at the time of cutting are inferior, but also inferior in corrosion resistance. Yes. Comparative steel No. No. 37 is inferior in cold forgeability and hot manufacturability because the amount of P (%) is high. Comparative steel No. No. 38 is inferior in corrosion resistance because the Cr amount (%) is low. Comparative steel No. No. 39 is uneconomical because the Cr content (%) is high. Comparative steel No. In No. 40, since the Sn amount (%) is low, the tool life at the time of cutting and chip disposal are poor. Comparative steel No. In No. 41, since the Sn amount (%) is high, the material becomes hard, and the tool life and hot manufacturability at the time of cutting are inferior.
[0038]
Comparative steel No. In No. 42, since the amount of Cu (%) is low, the segregation of Bi is inferior, and the production yield is inferior. Comparative steel No. In No. 43, since the amount of Cu (%) is high, it is not only inferior in cold forgeability and tool life, but also inferior in hot productivity. Comparative steel No. No. 44 is not only inferior in hot workability due to a high Bi amount (%), but also has a segregation of Bi, and is inferior in production yield and production cost. Comparative steel No. In No. 45, since the Mg amount (%) is high, the cold forgeability and the tool life are inferior. Comparative steel No. In No. 46, since the Ag amount (%) is high, the hot productivity is inferior.
[0039]
Comparative steel No. 47 and 48 are inferior in cold forgeability and tool life because the Ni amount (%) and Co amount (%) are high. Comparative steel No. In No. 49, since the Mo amount (%) is high, it is not only inferior in cold forgeability and tool life but also uneconomical.
Comparative steel No. In 50 to 54, the Nb amount (%), V amount (%), W amount (%), Ta amount (%), and Zr amount (%) are high, respectively, so that cold forgeability and tool life are inferior. .
[0040]
Comparative steel No. In No. 55, since the amount of B (%) is high, it is not only inferior in hot productivity but also inferior in corrosion resistance. Comparative steel No. In 56, since the Ca amount (%) is high, the corrosion resistance is deteriorated and it is uneconomical. Comparative steel No. No. 57 is inferior in hot manufacturability because the Y amount (%) is high. Comparative steel No. In No. 58, since the Ti amount (%) is high, the tool life is inferior.
[0041]
Next, when only machinability is required, that is, when S is 0.05% or more, the machinability, hot manufacturability, and segregation state (manufacturing yield / manufacturing cost) were evaluated. A cutting test was carried out under the conditions shown in Table 4, and the tool life and chip shape were used. The tool life was evaluated by the amount of flank wear, and the tool life was evaluated as ○ when the flank wear amount after 30 minutes was 30 μm or less, and × when it was over 30 μm. In addition, the chip shape was evaluated as “◯” if it was regularly divided into curls, and “×” in the case of irregular-shaped continuous cutting.
The tool life and chip disposal of the steel of the present invention were both good.
[0042]
For the hot manufacturability, a test piece (φ8 mm × 110 mm) was cut out from the slab surface layer, and the hot workability was evaluated by a thermorester test. The evaluation was performed at the breaking drawing value at 1000 ° C., and the hot workability was judged to be good (good) if the drawing value at that time was 60% or more. The hot workability of the steel of the present invention was all good.
[0043]
The segregation of the bar steel was evaluated from the ratio of the analysis values of Sn, S, Bi free cutting elements by collecting chips for component analysis from the top and bottom of the bar steel. If the analysis value of the element of Sn, S, Bi at the bottom is less than 1.3 times the value (segregation value) at the top, the evaluation of segregation is good (good), and if it is 1.3 times or more, segregation. Was evaluated as x (defect). That is, if it was x, it was judged that the production yield was bad and the production cost was high.
All the evaluations of segregation of the present invention were ○.
[0044]
These test results are shown in Table 7.
Invention Steel No. 61-72 is Sn-added ferritic stainless steel, further S, Bi, in addition to the Cu or the like, and subjected to oxide control, chip disposability without using a strong element of toxic Pb or the like, the tool Excellent life, hot manufacturability and segregation (manufacturing yield / cost). However, steel No. 1 of the present invention in which Si and Al are reduced and O is increased. Nos. 59 and 62 are Nos. Of steels of the present invention having high Si and Al and low O. Compared to 63 and 64, the tool life is excellent.
In Table 7, steel No. 59 and 60 are reference steels.
[0045]
On the other hand, comparative steel No. In 73-83, the following faults were observed.
Comparative steel No. In 73 and 74, since the amount of C (%) and the amount of N (%) are high, the tool life is inferior. Comparative steel No. In 75, since S amount (%) is high, it is inferior to hot productivity. Comparative steel No. No. 76 is inferior in hot manufacturability because the amount of P (%) is high. Comparative steel No. In No. 77, since the Sn amount (%) is low, it is inferior in tool life and chip disposal during cutting. Comparative steel No. In No. 78, since the amount of Cu (%) is high, the material is hard and the tool life at the time of cutting is inferior, and the hot productivity is also inferior.
[0046]
Comparative steel No. In No. 79, since the Cu content (%) is low, not only the hot productivity is low, but Bi is segregated and the production yield is poor. Comparative steel No. In No. 80, since the Bi amount (%) is high, not only the hot productivity is low, but Bi is segregated and the production yield is poor. Comparative steel No. In 81, since the Mg amount (%) is high, the tool life at the time of cutting is inferior. Comparative steel No. In No. 82, since the Ag amount (%) is high, the hot productivity is poor. Comparative steel No. In No. 83, the amount of Zr (%) is high and the tool life during cutting is poor.
[0047]
[Table 1]

[0048]
[Table 2]

[0049]
[Table 3]

[0050]
[Table 4]

[0051]
[Table 5]

[0052]
[Table 6]

[0053]
[Table 7]

[0054]
【Effect of the invention】
According to the present invention, the ferritic S free cutting stainless steel, Sn in pressurized forte Bi, Cu is added, etc., even a by controlling the form of inclusions, the problem on environmental sanitation Pb, Se, A ferritic free-cutting stainless steel excellent in machinability, hot manufacturability, cold forgeability, production yield and production cost can be obtained at low cost without Te.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the drilling time and the Sn amount of 18% Cr-0.02% C-0.02% N-based stainless steel material (4 mm thickness).

Claims (9)

% By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05-1.0%
S: 0.005 to 0.05%,
Cu: 0.2 to 0.7%,
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities. % By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05-1.0%
S: 0.05 to 0.4%,
Cu: 0.2 to 0.7%,
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities. % By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05 to 1.0%,
S: 0.005 to 0.05%,
Cu: 0.5 to 2.5%,
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
Bi: 0.01 to 0.15%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities. % By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05 to 1.0%,
S: 0.05 to 0.4%,
Cu: 0.5 to 2.5%,
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
Bi: 0.01 to 0.15%
A ferritic free-cutting stainless steel characterized by comprising the balance Fe and inevitable impurities. % By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05 to 1.0%,
S: 0.005 to 0.05%,
Cu: 0.5 to 2.5%,
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
Bi: 0.01 to 0.15%,
and,
Mg: 0.0005 to 0.05%,
Ag: Ferritic free-cutting stainless steel containing at least one of 0.02 to 0.15% and comprising the balance Fe and inevitable impurities. % By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05 to 1.0%,
S: 0.05 to 0.4%,
Cu: 0.5 to 2.5%,
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
Bi: 0.01 to 0.15%,
and,
Mg: 0.0005 to 0.05%,
Ag: Ferritic free-cutting stainless steel containing at least one of 0.02 to 0.15% and comprising the balance Fe and inevitable impurities. % By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05 to 1.0%,
S: 0.005 to 0.05%,
Cu: 0.2-0.9%
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
and,
B: 0.0005 to 0.02%,
Ca: Ferritic free-cutting stainless steel containing at least one of 0.0005 to 0.02%, and remaining balance Fe and inevitable impurities. % By mass
C: 0.08% or less,
Mn: 0.05 to 3.0%
P: 0.01-0.1%
Cr: 15-22%,
Sn: 0.03-0.3%,
N: 0.08% or less,
Ni: 0.05 to 1.0%,
S: 0.05 to 0.4%,
Cu: 0.2-0.9%
Si: 0.05 to 0.5%,
Al: 0.015% or less,
Mo: 0.01 to 3.0%,
O: 0.003-0.015%,
and,
B: 0.0005 to 0.02%,
Ca: Ferritic free-cutting stainless steel containing at least one of 0.0005 to 0.02%, and remaining balance Fe and inevitable impurities. The ferritic free-cutting stainless steel according to claim 1 or 2 , further comprising, in mass%, Zr: 0.005 to 0.3%.

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