DE60029364T2 - cutting alloy - Google Patents

Description

State of technology

The The present invention relates to free-cutting alloys with excellent machinability.

alloys have diverse Applications due to a variety of properties. An automatic alloy, which are excellent in machinability is selected in one case for the Improvement of productivity. For example, to improve machinability a free-cutting alloy, which is the machinability improving element such as S, Pb, Se or Bi (hereinafter referred to as the denotes the machinability improving element) contains widely used. In particular, in a case where the machine Machinability due to a precise finish in the Editing or for other reasons especially necessary, not only the content of such the machinability improving element in one Alloy increased, but the elements also become an alloy in combination added.

While S, which for the machinability improvement has been widely used in many cases is added in the form of MnS, due to its addition to a Alloy in a big one Quantity a deterioration of corrosion resistance, thermoformability and the cold workability of the alloy. In addition, one in the Alloy inserted Sulfur component in the environment in the form of a sulfur-containing Gases released in the surrounding areas of the parts easily causes sulfur contamination when the alloy is exposed to air becomes. Therefore, there is a need to prevent the release of sulfur-containing gas (hereinafter referred to as the improvement in the exhaust resistance designated). Elements such as S, Se and Te, however, worsen the magnetic properties in an electromagnetic stainless steel or similar very strong.

Therefore were different proposals submitted: the Mn content is limited, the Cr content in the sulfide will be raised, or, in the case of the presence of S, Ti is combined with S is added to disperse the sulfide in spherical form (see for example JP-A-98-46292 or JP-A-81-16653). The increase of Cr content in the sulfide however, can greatly reduce the machinability and lead to thermoformability, and therefore such an alloy is in many cases limited in its application.

R. Kiessling et al. "non metallic inclusions in steel ", 1978 concerns sulfide inclusions in steel.

The GB 1 519 313 relates to a stainless steel alloy and a ferrite free cutting steel having excellent machinability and high corrosion resistance.

Automatic stainless steels are in JP-A-10-130764, JP-A-11-140597 (US-A-6033625), JP-A-63-093843 or in US-A-4705581, wherein sulfides or selenides and / or Teluride be used.

consequently It is an object of the present invention to provide a free-cutting alloy which is excellent in machinability, showing outstanding properties as an alloy, such as corrosion resistance, Thermoformability and cold formability or specific magnetic Properties which match those of conventional alloys are comparable.

Summary the invention

Around to solve the above mentioned problem is a vitrified alloy of the present invention by a Automate alloy according to claims 1 to 4 marked. "(Ti, Zr) "means a or both of Ti and Zr.

The machinability of an alloy can be improved by forming the above-described (Ti, Zr) -based compound in a matrix metal phase of the alloy. Moreover, by forming this compound in the alloy, the formation of compounds such as MnS and (Mn, Cr) S, which easily reduce the corrosion resistance and thermoformability of the alloy, can be prevented or prevented, whereby the corrosion resistance, thermoformability and cold workability are improved sufficiently good level can be maintained. That is, according to the present invention, an automatic alloy can be realized which is excellent in machinability without impairing useful alloy properties such as hardness, corrosion resistance, thermoformability, cold formability and specific magnetic properties.

Furthermore is one formed in the vending alloy of the present invention (Ti, Zr) -based compound distributed in the alloy structure. The machinability of an alloy can be further increased in particular by distributing or dispersing the compound in an alloy structure. To increase this effect lies the particle size of the (Ti, Zr) -based compound, as in the structure of a polished Section of the alloy is observed, preferably for example approximately in the range of 0.1 to 30 μm on average, and above In addition, there is an area ratio of Compound in the structure preferably in the range of 1 to 20%, wherein the particle size by the maximum distance between two parallel lines, which one surrounded particles to be considered, is defined when the parallel Lines are drawn in such a way that they are in one area including of the particle to be considered, while the direction of the parallel Changed lines becomes.

The above-described (Ti, Zr) -based alloy may include at least one compound expressed by the composition formula (Ti, Zr) ₄ (S, Se, Te) ₂ C ₂ (hereinafter also referred to as carbosulfide / selenide) wherein one or more of Ti and Zr may be contained in the compound and wherein one or more of S, Se and Te may be contained in the compound. By forming a compound in the form of the above-described composition formula, not only the machinability of an alloy can be improved, but also the corrosion resistance can be increased.

It should be understood that the identification of a (Ti, Zr) -based compound in an alloy by X-ray diffraction (for example, a diffractometer method), an electron probe microanalysis method (EPMA), and a similar technique can be done. For example, the presence or absence of the compound (Ti, Zr) ₄ (S, Se, Te) ₂ C _{2 can} be confirmed by whether or not a peak corresponding to the compound appears in the diffraction pattern measured by an X-ray diffractometer. In addition, a region in the alloy structure in which the joint is formed can also be determined by comparing between two-dimensional mapping results of characteristic X-ray intensities of Ti, Zr, S, Se, and C by EPMA surface analysis performed on a section structure of the alloy be given.

Short description the drawings

The 1 FIG. 12 is a graph showing compositional ranges in combination of a content of one or more of Ti and Zr, a content of C and a content of one or more of S, Se and Te in an alloy of the present invention formed as electromagnetic stainless steel;

2 Fig. 12 is a graph showing an example of a Schaeffler diagram;

3 is a graph showing the relationship between B1 or Hc and α in Example 1;

4 Fig. 12 is a graph showing the relationship between the boring time and the cracking threshold working ratio and α in Example 1;

5 Fig. 12 is a graph showing the relationship between the pitting potential (Vc) and α in Example 1;

6 FIG. 12 is a graph showing the dependencies of the solubility products on the temperature of the components of TiO, TiN, Ti ₄ C ₂ S ₂ , TiC, TiS and CrS in γ-Fe.

preferred embodiments the invention

More concretely, the present invention can preferably be applied to an alloy constituted as a stainless steel. In this case, such an alloy preferably contains one or more of Ti and Zr such that W _Ti + 0.52W satisfies _Zr = 0.05 to 0.5 mass%, wherein W _Ti and W _{Zr indicate} the respective content in mass%. specify by Ti and Zr; and one or more of S and Te to form a (Ti, Zr) based compound without any deterioration in the stainless steel properties. Reference is made to the formulas 1 and 2 in claim 1.

Ti and Zr are indispensable elements for forming a (Ti, Zr) -based compound, which plays a central role in the practice of the effect of improving the machinability of a free-cutting alloy according to the present invention. The above effect, which is exhibited when Ti and Zr are incorporated in an alloy, is determined by the sum of the number of atoms (or the sum of the number of moles) irrespective of the kinds of the metals Ti or Zr. Since the ratio between the atomic weights is approximately 1: 0.52, Ti with a smaller atomic weight shows a larger effect at a lower mass. Thus, the value of W _Ti + 0.52W _{Zr represents} a composition parameter which reflects the sum of the atomic numbers of Zr and Ti contained in an alloy.

While the Composition as stainless steel of the present invention described above In addition, machinability as an alloy is also in an electromagnetic alloy which is considered to be a functional Material is used, required. Although electromagnetic Alloys in many cases one poor machinability were not just the corrosion resistance and cold formability, but also electromagnetic properties in such cases deteriorates in which the machinability improves Elements such as S and Pb improve machinability were added. About that in addition, it has been difficult to improve machinability Maintaining excellent electromagnetic properties, since the properties of the alloy through subtle changes in the equilibria between the constituent elements change greatly. According to the present Invention may have an effect of improving machinability be achieved while maintain the properties in the electromagnetic alloy become.

Concrete said, the present invention may preferably be described as electromagnetic Alloy (hereinafter referred to as fourth selection invention designated). The inventors of the present invention have the following Results found and the fourth selection invention based on them completed: When in an electromagnetic ferrite alloy one or more of Ti and Zr, C and one or more of S, Se and Te in combination the components are added in combinations of the specific ones Contents: a content of one or more of Ti and Zr in the range of 0.05 to 0.5 mass% with respect to Ti% + 0.52 Zr% (which is referred to as X); a content of C is in the ranges from 0.02X to 0.06X mass%, 0.19X to 0.26X mass% or 0.02X to 0.26X; and a content of one or more of S, Se and Te is in the range of (Z - 0.07) X to (Z + 0.07) X mass%, (Z + 0.07) X to (Z + 0.45) X mass% or (Z + 0.45) X to (Z + 0.70) X mass%, where S% + 0.41Se% + 0.25Te% is denoted by Y. This can make the machinability be improved while the magnetically soft properties, the cold formability and the corrosion resistance be set at a good level. In the description of fourth selection invention means the expression of an element symbol with a following%, such as Ti%, Zr%, S%, Se%, Te% or C%, the content in% by mass of the corresponding component, as indicated by the element symbol is specified. C / X and C% / X in the following description the same meaning.

That is, the fourth selection invention of the present invention formed as electromagnetic stainless steel contains: 0.01 to 3 mass%; 2 mass% or less Mn; 5 to 25 mass% Cr; 0.01 to 5 mass% Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass% with respect to X of the following formula 1; C in the range of 0.02X to 0.06X mass% (C / X = 0.02 to 0.06) or 0.19X to 0.26X mass% (C / X = 0.19 to 0, 26), wherein X is expressed by the following formula 1; one or more of S, Se and Te in the range of (Z-0.07) X to (Z + 0.07) X mass%, wherein X, Z and Y are the values of the following formulas 1, 3 and 2, respectively are. Further, if necessary, it contains one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V. In addition, it contains one or more of Pb, B and SEM in the respective contents of 0.15 mass% or less for Pb, as necessary. 0.01 mass% or less for B; and 0.1 mass% or less for REM; the remainder being Fe and unavoidable impurities: Ti% + 0.52Zr% = X Formula 1, S% + 0.41Se% + 0.25Te% = Y Formula 2 and 32 (C% / X - 0.125) 2 = Z Formula 3

A Alloy based on the fourth selection invention contains, contains: 0.01 to 3% by mass of Si; 2 mass% or less Mn; 5 to 25 mass% Cr; 0.01 to 5 mass% Al; one or more of Ti and Zr in the Range of 0.05 to 0.5 mass% with respect to X of the following formula 1; C in the range of 0.02X to 0.26X mass% (C / X = 0.02 to 0.26), wherein X is expressed by the following formula 1; one or more of S, Se and Te in the range of (Z + 0.07) X to (Z + 0.45) X mass%, wherein X, Z and Y are values of the respective ones represent the following formulas 1, 3 and 2. Furthermore, it contains ever one or more selected from the group consisting as needed of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Not a word; 1 mass% or less for Nb and 1 mass% or less for V. Contains further as needed one or more of Pb, B and REM in the respective Ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM; furthermore, the balance is Fe and unavoidable impurities.

A Free-cutting alloy relating to the fourth selection invention, includes: 0.01 to 3% by mass of Si; 2 mass% or less Mn; 5 to 25 mass% Cr; 0.01 to 5 mass% Al; one or more of Ti and Zr in the Range of 0.05 to 0.5 mass% with respect to X of the following formula 1; C in the range of 0.02X to 0.26X mass%, if X is through the following formula 1 is expressed is; one or more of S, Se and Te in the range of (Z + 0.45) X to (Z + 0.70) X mass%, where X, Z and Y are represented by the respective the following formulas 1, 3 and 2 are given. In addition, it contains each one or more selected from the group consisting as needed of Ni, Cu, Mo, Nb and V in contents of 2 mass% or less Ni; 2 mass% or less of Cu; 2 mass% or less Mo; 1 mass% or less Nb; 1 mass% or less V; and the rest is Fe and unavoidable impurities.

Furthermore will be a detailed description of the machine alloy, which referring to the fourth selection invention, given as follows: The composition is determined by a combination of the content or more of Ti and Zr, a content of C and a content to one or more of S, Se and Te, which are mainly in ferritic stainless steel are specified; in addition to one or more of Ti and Zr, C and one or more of S, Contains Se and Te they are: 0.01 to 3% by mass of Si; 2 mass% or less Mn; 5 to 25 Mass% Cr; 0.01 up to 5 mass% Al. About that contains as needed one or more, selected from the group consisting of Ni, Cu, Mo, Nb and V in the ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V. It also contains each one or more of Pb, B and REM in the respective one as needed Contents of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM; and the rest is Fe and unavoidable impurities.

The Combinations of a content of one or more of Ti and Zr, a content of C and a salary of one or more S, Se and Te are combinations of one or more of Ti and Zr in the range of 0.05 to 0.5 mass% with respect to Ti% + 0.52 Zr% (which is indicated by X); C in the range of 0.02X to 0.06X Mass% (C / X = 0.02 to 0.06), 0.19X to 0.26X mass% (C / X = 0.19 to 0.26) or 0.02X to 0.26X mass% (C / X = 0.02 to 0.26); and one or more of S, Se and Te in the range of (Z-0.07) X to (Z + 0.07) X mass% ((Z - 0.07) ≦ Y / X ≦ (Z + 0.07)), (Z + 0.07) X to (Z + 0.45) X mass% ((Z - 0.07) ≦ Y / X ≦ (Z + 0.45)) or (Z + 0.45) X to (Z + 0.70) X mass% ((Z-0.45) ≦ Y / X ≦ (Z + 0.70)).

gibt eine Prüflingsnummer eines erfindungsgemäßen Stahls des Beispiels 1 an.Hereinafter, the combinations of the salary ranges with reference to the in 1 in which the abscissa for applying C / X is used and the ordinate for applying Y / X is used. A first combination of one or more of Ti and Zr; A content of C and a content of one or more of S, Se, and Te is a range passing through a straight line perpendicular to the abscissa passing through the position C / X = 0.02, a straight line, perpendicular to the abscissa passing through the position of C / X = 0.06 and curves of Y / X = 32 (C / X - 0.125) ² - 0.07 and Y / X = 32 (C / X - 0.125) ² - 0.07, wherein the formulas Y / X = 32 (C / X - 0.125) ² - 0.07 and Y / X = 32 (C / X - 0.125) ² - 0.07 by replacing Z = 32 (C / X - 0.125) ² in the above described (Z - 0.07) ≦ Y / X ≦ (Z + 0.07), ie Y / X = (Z - 0.07) to (Z + 0.07) is included. In addition, the dashed line is in 1 , Y / X = 32 (C / X - 0.125) ² , a curve circumscribed by the C / X axis (a value on the Y / X axis = 0), and α in 1 is defined by the formula Y / X = 32 (C / X - 0.125) ² = α. In addition, the label indicates O with a number in 1 a sample number of a steel of the fourth selection invention of the present invention of Example 1, and a label

indicates a sample number of a steel according to the invention of Example 1.

A second combination of a content of one or more of Ti and Zr; A content of C and one or more of S, Se and Te is a region passing through a straight line perpendicular to the abscissa passing through a position of C / X = 0.19, a straight line perpendicular to the Abscissa passing through a position of C / X = 0.26 and curves of Y / X = 32 (C / X - 0.125) ² - 0.07 and Y / X = 32 (C / X - 0.125) ² + 0.07 in 1 is included. A third combination of one or more of Ti and Zr; of a content of C and one or more of S, Se and Te is a region passing through a straight line perpendicular to the abscissa passing through a position of C / X = 0.02, a straight line perpendicular to the Abscissa passing through a position of C / X = 0.26 and curves of Y / X = 32 (C / X - 0.125) ² + 0.07 and Y / X = 32 (C / X - 0.125) ² + 0.45 in 1 is included.

A fourth combination of a content of one or more of Ti and Zr; of a content of C and one or more of S, Se and Te is a region passing through a straight line perpendicular to the abscissa passing through a position of C / X = 0.02, a straight line perpendicular to the Abscissa passing through a position of C / X = 0.26 and curves of Y / X = 32 (C / X - 0.125) ² + 0.45 and Y / X = 32 (C / X - 0.125) ² + 0.70 in 1 is included.

below will be a description of the reasons given why the elements and their contents for the free-cutting alloy, the refers to the fourth selection invention, are selected as follows:

(1) 0.01 to 3 mass% Si

Si is not only as a deoxidizer, but also as a contributor to increase the maximum permeability and the reduction of the coercive force among the magnetically soft ones Features useful as electromagnetic stainless steel and serves over it out to an increase in electrical resistance and to improve reliability in a high frequency band. Therefore, Si is added for these purposes. While a Si content of 0.01% or higher is necessary to achieve the effect because at too high a salary the hardness increases and the cold workability is deteriorated, is the content diminished when cold workability as a more important property is considered, and provided increases in the magnetically soft Characteristics as well as the high frequency reliability are mainly due to the addition of Al, as described below, compensated accordingly a reduction of the Si content. However, the upper limit of the Si content is set to 3 mass% when machinability is considered an important feature.

(2) 2 mass% or less Mn

Mn is a useful as a deoxidizer Element. Since, however, with an Mn content of above 2% by mass, the magnetically soft properties are degraded, the Mn content becomes set to 2 mass% or less.

(3) 5 to 25 mass% Cr

Cr is useful for the Improvement of corrosion resistance and the electrical resistance of steel as well as for the improvement Machinability by Formation of Cr (S, Se, Te) with S, Se and Te, which are described below. consequently becomes Cr for added these improvements. Although Cr necessarily in the Range of 5 mass% or higher must be contained, the Cr content is reduced above 25% by mass the cold formability. Consequently, the Cr content is set to 5 to 25 mass%.

(4) 0.01 to 5 mass% al

al Not only is it useful as a deoxidizer, it also helps to increase the maximum permeability and to reduce the coercive force and beyond useful to increase of electrical resistance and to improve reliability in a high-frequency band, similar like Si. Therefore, Al becomes for added these improvements. Although Al necessarily in one Content of above 0.01 mass% is included to the effects Showing is not just a specific refinement process required, but also the cold formability is deteriorated, when the Al content exceeds 5 mass%. Accordingly, the Al content is set to 0.01 to 5 mass%.

(5) One or more off Ti and Zr in the range of 0.05 to 0.5 mass% with respect to Ti% + 0.52 Zr% = X

Ti and Zr form (Ti, Zr) ₄ C ₂ (S, Se, Te) ₂ and / or (Ti, Zr) (S, Se, Te) in coexistence with C, S, Se and Te in support of increasing the and, since among the two (Ti, Zr) ₄ C ₂ (S, Se, Te) _2, particularly neither the magnetically soft properties nor the corrosion resistance deteriorates and contributes to the improvement of machinability without any loss of cold workability due to the fine distribution therefore, the elements are added for these improvements. Although the content of the elements alone or in combination must be 0.05 mass% or higher with respect to X in order to exhibit these effects, the magnetically soft properties are deteriorated when the content with respect to X is 0.5 mass%. exceeds. Accordingly, the content is set in the range of 0.05 to 0.5 mass% with respect to X.

(6) C in the range of 0.02X to 0.06X mass%, 0.19X to 0.26X mass% or 0.02X to 0.26X mass%

The reason why the C content is 0.02X to 0.06X mass% (0.02 ≤ C / X ≤ 0.06) or 0.19X to 0.26X mass% (0.19 ≤ C / X ≤ 0.26), where | α | ≤ 0.07, where | α | is the absolute value of α and is used below, and α = Y / X - 32 (C / X - 0.125) ² (see 1 ) is that with such adjusted compositions in an electromagnetic stainless steel, the magnetically soft properties and the cold workability are particularly good, the machinability due to the distribution in a fine particle state of (Ti, Zr) ₄ C ₂ (S , Se, Te) ₂ and (Ti, Zr) (S, Se, Te) is as good as the latter is formed in a small amount, and moreover the corrosion resistance is also good, wherein (Ti, Zr) ₄ C ₂ (S, Se, Te) ₂ has little effect on the deterioration of magnetically soft properties. The excellent magnetically soft properties in the range of this α are in the extremely low proportion of the presence of (Ti, Zr) C, (Ti, Zr) (S, Se, Te) and Mn (S, Se, Te).

In the amount range of C of C / X <0.02 (C <0.02X mass%) and 0.06 <C / X <0.19 (the C content exceeds 0.06X mass% and is less 0.19X mass%), the formation of (Ti, Zr) ₄ C ₂ (S, Se, Te) _{2 is} extremely small in amount, which exerts little effect, but (Ti, Zr) C in the Amount range of C of C / X> 0.26 (C> 0.26X mass%), and on the contrary, the magnetically soft properties, the cold moldability and the corrosion resistance are deteriorated. Accordingly, the C content is in the ranges of 0.02 ≦ C / X ≦ 0.06 (0.02X to 0.06X mass%) or 0.19 ≦ C / X ≦ 0.26 (0.19X to 0 , 26X mass%).

Moreover, the reason why the C content is in the composition range of 0.02X to 0.26X mass% (0.02 ≦ C / X ≦ 0.26), wherein 0.07 ≦ α ≦ 0.45 in that the electromagnetic stainless steel having good machinability, good magnetically soft properties and good cold formability is formed by the formation of (Ti, Zr) ₄ C ₂ (S, Se, Te) ₂ and (Ti, Zr) (S, Se, Te), which are excellent in corrosion resistance, can be obtained in a slightly increased amount. However, in the range of C <0.02X mass% (C / X <0.02), the magnetically soft properties are due to the decrease in formation of (Ti, Zr) ₄ C ₂ (S, Se, Te) ₂ and increase in (Ti, Zr) (S, Se, Te) and in the range of C> 0.26X (C / X> 0.26) are the magnetically soft properties, cold workability and corrosion resistance due to the increase in (Ti, Zr) C deteriorates. Accordingly, the C amount range is limited to C = 0.02X to 0.26X mass% (0.02 ≦ C / X ≦ 0.26).

Further is the reason why the ranges of the C content on the composition range from 0.02X to 0.26X mass% (0.02 ≦ C / X ≦ 0.26), wherein 0.45 ≦ α ≦ 0.70, therein; in that due to the increase in (Ti, Zr) S, Cr (S, Se, Te) and Mn (S, Se, Te) an electromagnetic stainless steel can be obtained which a particularly excellent machinability, in one practicable range corrosion resistance and magnetically soft Properties shows, although the cold formability with a high employment difficult to achieve. However, in the composition range of α> 0.70 and C <0.02X mass% (C / X <0.02) the magnetically soft properties and corrosion resistance severely degraded due to the increase in (Ti, Zr) S, Cr (S, Se, Te) and Mn (S, Se, Te). About that In addition, the compositional range of C> 0.26X mass% (C / X> 0.26) is the decrease in the magnetic soft properties and in the corrosion resistance due to the increase in (Ti, Zr) C large. Accordingly, the C content is C = 0.02X to 0.26X mass% (0.02 ≤ C / X ≤ 0.26), in which 0.45 ≤ α ≤ 0.70 is limited.

One or more of S, Se and Te are in the range of (Z-0.07) X to (Z + 0.07) X mass%, (Z + 0.07) X to (Z + 0.45 ) X mass% or (Z + 0.45) X to (Z + 0.70) X mass%, where Y = S% + 0.41Se% + 0.25Te% is given by Y and Z = 32 (C / X - 0.125) ² .

In in the case where Y is in the range of (Z-0.07) X to (Z + 0.07) X mass% lies.

The reason why Y is set to (Z-0.07) X to (Z + 0.07) X mass% (-0.07≤a≤0.07) and C is set to 0.02X to 0.06X Mass% (0.02 ≤ C / X ≤ 0.06 or 0.19X to 0.26X mass% (0.19 ≤ C / X ≤ 0.26) is set in that in the electromagnetic stainless steel The composition is particularly excellent in magnetically soft properties and cold workability, machinability due to distribution in a fine state of (Ti, Zr) ₄ C ₂ (S, Se, Te) ₂ and (Ti, Zr) (S, Se In addition, the corrosion resistance is also good, but if Y is less than (Z - 0.07) X%, that is, if Y / X is smaller than 32 (C, Te), the latter is formed in a small amount / X - 0.125) ² - 0.07, the formation of (Ti, Zr) ₄ C ₂ (S, Se, Te) _{2 is} extremely small in amount, and thereby its effect is poor, whereas when Y is larger than (Z + 0.07) X mass%, ie when Y / X is greater than 32 (C / X - 0.125) ² + 0.0 7, the magnetically soft properties, cold formability and corrosion resistance are in contrast deteriorated. Therefore, Y is set in the range of (Z-0.07) X to (Z + 0.07) X mass%.

Y in the range of (Z + 0.07) X to (Z + 0.45) X mass%

The reason why Y is set in the range of Z + 0.07) X to (Z + 0.45) X mass% (0.07 α ≤ 0.45) and C in the range of 0.02X to 0.26X mass% is that in the electromagnetic stainless steel having the composition excellent corrosion resistance and machinability can be realized, which is better than when Y is in the range of (Z-0.07) X to (Z + 0.07) X mass%. In addition, the good magnetically soft properties and the good cold formability due to the formation of (Ti, Zr) ₄ C ₂ (S, Se, Te) ₂ and (Ti, Zr) (S, Se, Te) are slightly increased in the proportion. However, if Y is larger than (Z + 0.45) X mass%, that is, if Y / X is larger than 32 (C / X - 0.125) ² + 0.45, the machinability due to the increase in (Ti , Zr) S, Cr (S, Se, Te) and Mn (S, Se, Te) are even better, while cold formability, corrosion resistance and magnetically soft properties are deteriorated. Therefore, Y is set in the range of (Z + 0.07) X to (Z + 0.45) X mass%.

Y in the range of (Z + 0.45) X to (Z + 0.70) X mass%

The reason why Y is set in the composition range of Z + 0.45) X to (Z + 0.70) X mass% (0.45 α ≦ 0.70) and C in the range of 0.02X to 0.26X mass% (0.02 ≦ C / X ≦ 0.26) is that in the electromagnetic stainless steel having the composition, an electromagnetic stainless steel can be obtained, which is excellent in machinability, on a practical level having corrosion resistance and magnetically soft properties due to the increase in (Ti, Zr) S, Cr (S, Se, Te) and Mn (S, Se, Te), although the cold workability can hardly be achieved with a high duty ratio. However, when Y is set larger than (Z + 0.70) × mass%, ie, when Y / X is set larger than 32 (C / X - 0.125) ² + 0.70, the machinability is due to the Increases in (Ti, Zr) S, Cr (S, Se, Te) and Mn (S, Se, Te) continue to be excellent. On the other hand, since cold formability, corrosion resistance and magnetically soft properties fall below the level of practicability, Y is set in the range of (Z + 0.45) × to (Z + 0.70) × mass%.

2 mass% or less Ni, 2 mass% or less Cu, 2 mass% or less Mo, 1 mass% or less Nb and 1 mass% or less V

Ni, Cu, Mo, Nb and V are all useful for one further improvement of corrosion resistance in a free-cutting alloy, which refers to the fourth selection invention. Therefore, be the elements included in the electromagnetic stainless steel. However, if the elements are in excess are added to the respective upper limits, which are magnetic soft properties and the cold moldability deteriorates. Accordingly the contents are adjusted as described below.

0.15 mass% or less Pb; 0.01 mass% or less B; and 0.1 mass% or less REM

pb is an element which helps to further improve the machine Machinability is added. Because the effect of the improvement Machinability more than in a conventional case with a Pb content in half of the conventional case, the Pb content becomes set to 0.15 mass% or less.

Because B and REM are used to further improve cold workability in a steel of the free-cutting alloy, which are useful elements related to the fourth selection invention, the elements are added to the steel. However, if the contents exceed the respective upper limits described above, the hot and cold formability decreases. Accordingly, the contents are adjusted as described above. With respect to SEM, since low-level radioactive elements can be handled easily when used mainly, it is useful from this viewpoint, one or more, selected from the group consisting of Sc, Y, La, Ce, Pr, Nd To substitute Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. It is desirable to use light rare earth elements, especially La or Ce, from the standpoint of clearly exerting the effect and the price. However, there are no problems in mixing in traces of radioactive rare earth elements, such as Th and U, which inevitably remain in a separation process of the rare earth elements. In addition, rare earth elements such as mischmetal and didymium not separated can be used from the standpoint of reducing the raw material cost.

A description will be given of a manufacturing method for an automatic alloy relating to the fourth selection invention and designed as electromagnetic stainless steel, as follows:
The free-cutting alloy relating to the fourth selection invention has a composition containing one or more of Ti and Zr, a content of C, and a content of one or more of S, Se and Te, which elements are conventional in electromagnetic Stainless steels are included, wherein the contents are individually specified and the elements are included in combination of the contents in the alloy. Therefore, the electromagnetic stainless steel of the fourth selection invention can be manufactured by a manufacturing method similar to the conventional production method of electromagnetic stainless steels.

Examples

The The following experiments were performed to demonstrate the effects of the present Confirm the invention. It should be understood that in the following description the test alloy, which relates to the present invention, as inventive steel or alloy according to the invention or as a selection invention steel or as a selection invention alloy is designated.

Example 1: Electromagnetic stainless steel

The The following experiment was performed on a machine alloy which on a steel according to the invention the fourth selection invention, called electromagnetic stainless steel is formed relates. First, 7 kg blocks of the steels of the invention present invention and the comparative steels intended for testing purposes and their compositions in mass% in Tables 1 and 2 indicated are in an induction furnace in an Ar stream to give 80 bars mm diameter melted. Subsequently, the bars were under hot forming at a temperature in the range of 1,000 to 1,050 ° C to bars with formed a cross section of 22 mm in diameter, and then The bars to a diameter of 21 mm, followed by cold rolling into one Diameter of 18 mm processed. The rods rolled in this way became subjected to the tests. In Tables 1 and 2, the specimens are the Numbers 1 to 38 test bars the fourth selection invention steels, and the test specimens of Numbers 39 to 47 are test bars the stäh le invention. The test bars were considered in terms of magnetic properties, electrical Resistance, machinability, cold formability and corrosion resistance by the following measuring methods, which are described below are, examined:

Table 1

Table 2

measurement methods

1) Magnetic properties

A test piece in the form of a ring having an outer diameter of 10 mm and an inner diameter of 5 mm and a thickness of 5 mm was prepared for the measurement of magnetic properties. The test piece was subjected to magnetic hardening at 950 ° C, and then the DC magnetic characteristics including flux density and DC coercive force were measured by a BH loop tracer, the flux density B1 (KG) at a magnetic field of 1 Oe and the flux density B10 (KG) at a magnetic field of 10 Oe and the same current coercive force Hc (A / cm) measured. The relationships between the flux density B1 or the coercive force Nc and α are in the 3 shown.

2) Electrical resistance

Of the Electrical resistance was measured on test pieces, respectively were prepared by subjecting one test bar to one Cold wire drawing to obtain a wire with a diameter of 1 mm and by subsequent Carry out a vacuum hardening at 950 ° C from that.

3) Machinability

The machinability was evaluated as follows: a SKH 51 drill with a diameter of 5 mm was used in a test piece of steel for processing at a speed of 915 rpm. at a Load of 415 N at the cutting edge used, and the time in Seconds needed to drill a hole 10mm deep, was measured. The machinability was by a length of time judged in seconds.

4) cold formability

The Cold formability was determined by the breaking limit ratio (cracking threshold working ratio), and a procedure was follows: a test piece was in the shape of a cylinder with a diameter of 20 mm and a height made of 30 mm. The test piece was cured at 720 ° C, and subsequently was a pressure test on the test piece under a 400 t hydraulic press carried out, around the fractional limit working ratio to determine. The relationships of the drilling time or fracture limit working ratio and α are shown in Table 4.

5) Pitting potential (Pitting potential)

A test piece was made in the form of a disk whose size was 18 mm in diameter and 2 mm in thickness. The test piece was polished with emery papers up to the number 800 and subjected to magnetic hardening at 950 ° for 2 hours in a vacuum. Subsequently, the pitting potential Vc in mV on the test piece was measured in aqueous 3.5% NaCl solution at 30 ° C. The 5 shows the relationship between the pitting potential and α. The measurement results are shown in Tables 3 and 4.

Table 3

Table 4

As shown in Tables 3 and 4 and the 3 can be seen, excellent magnetic properties are shown: at | α | ≤ 0.07, Hc <1.0 A / cm and B1> 2.5 KG. The magnetic properties change rapidly in the range around α = 0.07 and stepwise in the range of 0.07 <α ≤ 0.45. The magnetic properties in relatively good ranges of 1.0 <Hc <1.5 A / cm and 1.0 <B1 <2.0 KG are maintained in the range of 0.07 <α ≤ 0.45. While the magnetic properties start increasing again at a point around α = 0.45, the magnetic properties show 1.4 <Hc <2.5 A / cm and 0.4 <B1 <1.0 KG in the range of 0.45 <α ≦ 0.70, which fall within the ranges which are practically usable as electromagnetic stainless steel.

Moreover, a relatively good machinability has been found in the range of | α | ≤ 0.70, which shows a drilling time in the range of 14 to 17 seconds, while the machinability does not show as clear correlation with α as the magnetic properties do, as shown in Tables 3 and 4 as well as 4 is apparent. Further, excellent cold workability in the same range of | α | ≤ 0.70, and a breaking limit working ratio is shown in the range of 80 to 86%. The machinability and the fracture limit work ratio each show a large fluctuation between α values that are close to each other, which is likely due to a difference in the content of Si, Mn and Cr as one of the reasons. In the range of 0.07 <α ≤ 0.45, a relatively good machinability was obtained, showing a drilling time in the range of 13 to 17 seconds. Further, a relatively good cold workability was exhibited, which shows a breaking limit working ratio in the range of 75 to 85%. On the other hand, in the range of 0.45 <α ≦ 0.70, excellent machinability, which has a drilling time in the range of 10 to 16 seconds, has been achieved While cold workability at a high duty ratio is difficult to show a break limit working ratio of 76% or less.

The specimens numbers 8, 10, 19, 21, 30 and 32, which contain Pb as a component, each have a short drilling time compared to specimens of the steel according to the invention of the present invention with respective α values close to those the examinees, which contain Pb lie. About that addition, the examinees have Nos. 8, 9 to 11, 19 to 22 and 30 to 33, which B and / or Contain REM as a component, each having a large fractional limit working ratio in Comparison to the test specimens of the steel according to the invention of the present invention with respective α-values, which are determined by the DUTs, which contain B and / or REM.

As shown in Tables 3 and 4 and the 5 becomes clear (wherein a high Cr stainless steel having an extremely high Vc and low Cr stainless steel having an extremely low Vc are excluded) is in the range of | α | ≤ 0.07, Vc in the range of -80 <Vc <0 in mV, and a good corrosion resistance is shown. In the range of 0.07 <α ≦ 0.45, Vc is in the range of -50 <Vc <70 in mV, and better corrosion resistance is shown. While Vc continues to decrease in the range of 0.45 <α ≤ 0.70, Vc is considered to be practically useful as long as Vc> -150 mV.

The specimens the numbers 6, 7, 10, 11, 17, 18, 21, 22, 28, 29, 32 and 33, which Ni, Cu, Mo, Nb and V contain what the corrosion resistance improved, compared with test specimens of the steel according to the invention of the present invention, each having α values close to the Ni, Cu, Mo, Nb and V containing test specimens lie, high Vc on. About that In addition, the candidates hold out the numbers 27 and 38, which is an element which indicates the corrosion resistance improved, contain, Vc on the same scale as those of the candidates of the steel according to the invention of the present invention having respective α values smaller than those of the candidates, which corrosion resistance-improving Contain elements.

The samples of Nos. 39 to 47 of the reference steel are outside the scope of the fourth selection invention, as in 1 is shown. Comparing the reference steel with the steel of the fourth selection invention, it is revealed that each of the reference steel of the reference steel has a fracture limit working ratio of 72% or less. Therefore, the steel is superior to the fourth selection invention in terms of cold workability. In addition, it is found that the steel of the fourth selection invention is better in magnetic properties and corrosion resistance than the reference steel when test specimens of both types are compared with respective α values which are close to each other. Further, when comparing the specimens of Nos. 39 to 42 of the reference steel with the examining numbers of the steel of the fourth selection invention, it is found that the steel of the fourth selection invention is better in terms of machinability than the reference steel. Comparing the reference steels of the test specimens Nos. 43 and 44 of the steels of the fourth selection invention, it is found that the steels of the fourth selection invention are better than the reference steels in the other properties, while both types of steel show approximately the same level of machinability. Comparing the reference steels of the test pieces of Nos. 45 to 47 with the steels of the fourth selection invention, it is found that the steels of the fourth selection invention have better magnetic properties and better corrosion resistance.

The 6 shows the dependencies of the solubility products on the temperature of the compounds TiO, TiN, Ti ₄ C ₂ S ₂ , TiC, TiS and CrS in γ-Fe (an austenitic phase). Since Zr has a chemical property analogous to Ti, and Se and Te have a chemical property analogous to S, it is believed that the compounds are formed in the following decreasing order of priority: (Ti, Zr) O> (Ti, Zr) N> (Ti, Zr) ₄ C ₂ (S, Se, Te)> (Ti, Zr) C> (Ti, Zr) (S, Se, Te)> Cr (S, Se, Te ). Further, it was confirmed by X-ray diffraction analysis that the compounds described above were present in the steel.

Claims (5)

Free-cutting alloy, which is designed as electromagnetic stainless steel, containing: 0.01 to 3 mass% Si; 2 mass% or less Mn; 5 to 25 mass% Cr; 0.01 to 5 mass% Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass% with respect to X of the following Formula 1; C in the range of 0.02X to 0.06X mass%, wherein X is expressed by the following formula 1; one or more of S, Se and Te such that the value Y is in the range of (Z-0.07) X to (Z + 0.07) X mass%, wherein X, Z and Y are values of the respective following Formulas 1, 3 and 2 are; and the remainder being Fe and unavoidable impurities: Ti% + 0.52Zr% = X Formula 1 S% + 0.41Se% + 0.25Te% = Y Formula 2 and 32 (C% / X - 0.125) 2 = Z Formula 3; and wherein a (Ti, Zr) -based compound containing one or more of Ti and Zr as a metal-element component, wherein C is an indispensable element as a bonding component with the metal-element component, and one or more of S, Se and Te are dispersed in a matrix metal phase; further optionally containing: one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; one or more of Pb, B and REM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM; one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; and further containing one or more of Pb, B and SEM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM. Free-cutting alloy, which is designed as electromagnetic stainless steel, containing: 0.01 to 3 mass% Si; 2 mass% or less Mn; 5 to 25 mass% Cr; 0.01 to 5 mass% Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass% with respect to X in the following Formula 1; C in the range of 0.19X to 0.26X mass%, wherein X is expressed by the following formula; one or more of S, Se and Te such that the value Y is in the range of (Z-0.07) X to (Z + 0.07) X mass%, wherein X, Z and Y are values of the respective following Formulas 1, 3 and 2, and the remainder being Fe and unavoidable impurities: Ti% + 0.52Zr% = X Formula 1 S% + 0.41Se% + 0.25Te% = Y Formula 2 and 32 (C% / X - 0.125) 2 = Z Formula 3; wherein a (Ti, Zr) -based compound containing one or more of Ti and Zr as a metal-element component, wherein C is an indispensable element as a bonding component with the metal-element component, and one or more of S Se and Te are dispersed in a matrix metal phase; further optionally containing: one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; one or more of Pb, B and REM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM; one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; and further containing one or more of Pb, B and SEM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM. Free-cutting alloy, which is designed as electromagnetic stainless steel, containing: 0.01 to 3 mass% Si; 2 mass% or less Mn; 5 to 25 mass% Cr; 0.01 to 5 mass% Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass% with respect to X of the following Formula 1; C in the range of 0.02X to 0.26X mass%, wherein X is expressed by the following formula 1; one or more of S, Se and Te such that the value Y is in the range of (Z + 0.07) X to (Z + 0.45) X, the lower limit not included is mass%, wherein X, Z and Y are values of the respective following formulas 1, 3 and 2; and the remainder being Fe and unavoidable impurities: Ti% + 0.52Zr% = X Formula 1 S% + 0.41Se% + 0.25Te% = Y Formula 2 and 32 (C% / X - 0.125) 2 = Z Formula 3; and wherein a (Ti, Zr) -based compound containing one or more of Ti and Zr as a metal-element component, wherein C is an indispensable element as a bonding component with the metal-element component, and one or more of S, Se and Te are dispersed in a matrix metal phase; further optionally containing: one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; one or more of Pb, B and REM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM; one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; and further containing one or more of Pb, B and SEM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM. Free-cutting alloy, which is designed as electromagnetic stainless steel, containing: 0.01 to 3 mass% Si; 2 mass% or less Mn; 5 to 25 mass% Cr; 0.01 to 5 mass% Al; one or more of Ti and Zr in the range of 0.05 to 0.5 mass% with respect to X of the following Formula 1; C in the range of 0.02X to 0.26X mass%, wherein X is expressed by the following formula 1; one or more of S, Se and Te such that the value Y is in the range of (Z + 0.45) X to (Z + 0.70) X, the lower limit not included, mass%, where in X , Z and Y are values of the respective following formulas 1, 3 and 2; and the remainder being Fe and unavoidable impurities: Ti% + 0.52Zr% = X Formula 1 S% + 0.41Se% + 0.25Te% = Y Formula 2 and 32 (C% / X - 0.125) 2 = Z Formula 3; and wherein a (Ti, Zr) -based compound containing one or more of Ti and Zr as a metal-element component, wherein C is an indispensable element as a bonding component with the metal-element component, and one or more of S, Se and Te are dispersed in a matrix metal phase; further optionally containing: one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; one or more of Pb, B and REM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM; one or more selected from the group consisting of Ni, Cu, Mo, Nb and V in the respective ranges of 2 mass% or less for Ni; 2 mass% or less for Cu; 2 mass% or less for Mo; 1 mass% or less for Nb and 1 mass% or less for V; and further containing one or more of Pb, B and SEM in the respective ranges of 0.15 mass% or less for Pb; 0.01 mass% or less for B; and 0.1 mass% or less for REM. Automate alloy according to one of claims 1 to 4, wherein the particle size of the (Ti, Zr) -based compound, as in the structure of a polished Section of the alloy is observed in the range of average 0.1 to 30 μm and where furthermore an area ratio of Compound in the structure is in the range of 1 to 20%.