CA1301489C - Cold drawn free-machining resulfurized and rephosphorized steel bars having controlled mechanical properties and controlled machinability - Google Patents
Cold drawn free-machining resulfurized and rephosphorized steel bars having controlled mechanical properties and controlled machinabilityInfo
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- CA1301489C CA1301489C CA000538742A CA538742A CA1301489C CA 1301489 C CA1301489 C CA 1301489C CA 000538742 A CA000538742 A CA 000538742A CA 538742 A CA538742 A CA 538742A CA 1301489 C CA1301489 C CA 1301489C
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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Abstract
Stanadyne Case 239 COLD DRAWN FREE-MACHINING RESULFURIZED
AND REPHOSPHORIZED STEEL BARS HAVING CONTROLLED
MECHANICAL PROPERTIES AND CONTROLLED MACHINABILITY
ABSTRACT OF THE DISCLOSURE
A cold drawn resulfurized and rephosphorized free-machining steel bar has the composition, by weight, C up to 0.08%; Mn 0.6% to 1.4%; Si up to 0.1%; P at least 0.03%;
S 0.25% to 0.50%; Cb 0.01% to 0.10%; V up to 0.1%; the sum of Ni, Cr, Mo, and Cu up to 0.15%; balance iron. The ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X
%S) / %Cb is from 2 to 50. The yield strength of the steel bar is further determined by the draft in cold drawing the bar from the hot rolled state and the size and cross section of the bar after draft.
AND REPHOSPHORIZED STEEL BARS HAVING CONTROLLED
MECHANICAL PROPERTIES AND CONTROLLED MACHINABILITY
ABSTRACT OF THE DISCLOSURE
A cold drawn resulfurized and rephosphorized free-machining steel bar has the composition, by weight, C up to 0.08%; Mn 0.6% to 1.4%; Si up to 0.1%; P at least 0.03%;
S 0.25% to 0.50%; Cb 0.01% to 0.10%; V up to 0.1%; the sum of Ni, Cr, Mo, and Cu up to 0.15%; balance iron. The ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X
%S) / %Cb is from 2 to 50. The yield strength of the steel bar is further determined by the draft in cold drawing the bar from the hot rolled state and the size and cross section of the bar after draft.
Description
13(~ 8~
SUMMARY OF THE INVENTION
The present invention relates to a free-machining resulfurized and rephosphorized cold drawn steel bar and, more particularly, to such a steel bar having a controlled chemis-try and whose yield strength is determined not only by the controlled chemical composition, but also by the size of the bar after hot rolling and the amount of draft used in reducing the bar.
A primary purpose of the invention is a cold drawn free-machining steel bar as described in which mechanical properties of the bar, particularly yield qtrength, can be determined on the basis of the chemical composition of the bar and the size, cross section, and applicable draft.
Another purpose is a free-machining cold drawn steel bar as described in which the amount of carbon is reduced accompanied by controlled amounts of columbium, which when accompanied by size-related optimization of the ratios of the ingredients in the chemical composition, provide a means for targeting yield strengths for desired bar application.
Another purpose is a cold drawn free-machining steel bar as described in which the necessary characteristics for increased machinability are optimized by the chemical composi-tion and by the mechanical configuration of the bar.
Another purpose is a resulfurized and rephosphorized free-machining steel bar as described having excellent ma-chinability characteri6tics which are provided by optimizing the relationship between steel chemistry, steelmaking, cold drawing practice and machining conditions.
Another purpose is a process of providing a cold drawn free-machining steel bar utilizing the chemical charac-teristics of the bar, the size and steelmaking procedures used in the bar, which has application to carbon steel, mangane~e i `
SUMMARY OF THE INVENTION
The present invention relates to a free-machining resulfurized and rephosphorized cold drawn steel bar and, more particularly, to such a steel bar having a controlled chemis-try and whose yield strength is determined not only by the controlled chemical composition, but also by the size of the bar after hot rolling and the amount of draft used in reducing the bar.
A primary purpose of the invention is a cold drawn free-machining steel bar as described in which mechanical properties of the bar, particularly yield qtrength, can be determined on the basis of the chemical composition of the bar and the size, cross section, and applicable draft.
Another purpose is a free-machining cold drawn steel bar as described in which the amount of carbon is reduced accompanied by controlled amounts of columbium, which when accompanied by size-related optimization of the ratios of the ingredients in the chemical composition, provide a means for targeting yield strengths for desired bar application.
Another purpose is a cold drawn free-machining steel bar as described in which the necessary characteristics for increased machinability are optimized by the chemical composi-tion and by the mechanical configuration of the bar.
Another purpose is a resulfurized and rephosphorized free-machining steel bar as described having excellent ma-chinability characteri6tics which are provided by optimizing the relationship between steel chemistry, steelmaking, cold drawing practice and machining conditions.
Another purpose is a process of providing a cold drawn free-machining steel bar utilizing the chemical charac-teristics of the bar, the size and steelmaking procedures used in the bar, which has application to carbon steel, mangane~e i `
~L
: ', ~3~'1489 steel, resulfurized and rephosphorized steel, microalloyed steel and high-strength steel.
Another purpose is a cold drawn free-machining steel bar as described in which the amounts and ratios of manganese, sulfur and columbium and the amount and pattern of deformation in cold drawing are controlled to provide optimum machinabil-ity.
Other purposes will appear in the ensuing specifica-tion and claims.
DETAILED DESCRIPTION OF THE INVENTION
It is well-known that certain elements, such as sulfur, lead, bismuth, tellurium and selenium, are useful for improving machinability of steel. Machinability is a complex and not a fully understood property. The problem is one in which the effect of the alloy composition, plastic flow of the metal workpiece and cutting dynamics are not readily recogniz-ed from the manner in which the alloy is machined by cutting tools in such operations as single point turning, forming, drilling, reaming, boring, shaving and threading. There is a gap in the available knowledge of material behavior between test results obtained from conventional, non-steady-state tension experiments and results obtained from cutting force data derived from in-process machining.
Metallurgists have long sought to improve the mach-inability of free-machining steel bars by modifying the chemi-cal composition, optimizing size, shape, distribution and chemical composition of inclusions to enhance the brittleness of the chip and increase lubrication at the tool/chip inter-face. Further, it is desired to prevent formation of theabrasive particles and microconstituents which are in the steel bar. For example, for the purpose of improving 13~1489 machinability varying amounts of one or more such elements as bismuth and tellurium (U.S. Patent No. 4,236,939); lead, bis-muth and tellurium and/or sulfur (U.S. Patent No. 4,244,737);
tellurium and sulfur (U.S. Patent No. 4,279,646) have been included in resulfurized and rephosphorized free-machining steels. Such products, however, have not completely satisfied the need for increased machinability of free-machining steel.
Prior efforts at increasing machinability have been more specifically directed to the chemical composition rather than attempting to optimize the chemical composition, the draft or percentage size reduction in cold forming and the size and cross section of the bar. The present invention is specifi-cally directed to increasing machinability by combining the optimum ratio of chemical ingredients, particularly, manga-nese, sulfur and columbium with optimum size and cross sec-tions for the bar, as well as the amount of cold working.
Thus, in the present invention, the chemical composition, draft, size and cross section of a bar are tailored to meet particular machinability applications.
The cold drawn free-machining resulfurized and re-phosphorized steel bar of the present invention has a chemical composition, by weight, consisting of C up to 0.08%; Mn 0.6%
to 1.4%; Si up to 0.1%; P at least 0.3%; S 0.25% to 0.50%;
Cb 0.01% to 0.10%; V up to 0.1%; the sum of Ni, Cr, Mo, and Cu up to 0.15% with the balance being iron. The ratio of manga-nese, sulfur and columbium is particulary important in provid-ing a steel bar of the appropriate chemical characteristics and in predicting the yield strength of a particular bar.
Thus, the ratio of %Mn / %S is from 1.6 to 4.0 and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
The yield strength of the bar and, hence, its machinability is determined by the raw material, size and the , - 13~14B9 draft. The raw material may be, considering the available types of products from the mill, hot rolled coil, hot rolled bars up to two inches in diameter and hot rolled bars having a diameter of at least two inches. Such stock, after hot roll-ing to the specified size, and being cut off in appropriate lengths, will then be cold drawn and the draft or the size reduction in cold drawing is also extremely important in determining yield strength of the finished bar.
Carbon up to_0/08%
Considering the roles of the different chemical elements in the composition and their influence on machinabil-ity and performance of the steel, a reduced carbon content is essential for assuring low work hardening and strain hardening of a steel subject to cold drawing and machining. A low car-bon content providing low strength in a resulfurized and rephosphorized steel, when combined with the sum of residual elements, such as nickel, chromium, molybdenum and copper not exceeding 0.15%, provides a product of relatively low ductil-ity and increased breakability of the chip formed at the tool-workpiece interface. If the residual elements are in-creased above the level specified, with the reduced carbon content specified, the product has increased ductility and decreased breakability of the chip, which are disadvantageous in a free-machining product. Moreover, an increase in the carbon content above 0.08% increases the formation of abrasive particles, creates a likelihood of increased fracture stress and an increase of surface hardness, particularly in cold ~ drawn hexagonal bars.
; Manganese 0.6% to 1.4%
The specified amount of manganese is important for the formation of manganese sulfide (MnS) based inclusions which exert influence on tool life~ Manganese promotes hard-:
~3~489 enability and increases the strength of cold drawn bars. The The actual specification of manganese in a particular bar is dependent upon the diameter of the hot rolled steel, the re-quired mechanical properties for the bar and the machining designation. The manganese content i9 increased with an increase in the size of bar and an increase in the target level of yield strength.
Silicon up to 0.1%
The silicon content should be limited to 0.1% as an increased amount of silicon substantially increases the amount of abrasive silicates in the finished product.
Sulfur 0.25% to 0.50%
Sulfur is also necessary for the formation of MnS
inclusions, and it is for this reason that the sulfur content should be at least 0.25%. The particular specification of sulfur in a particular bar depends on the size of the bar and the manganese content. The minimal sulfur content is utilized with a hot rolled coil as the raw material, whereas the maxi-mum sulfur content is required for large diameter cold drawn bars with increased yield strength up to approximately 80 ksi.
An excess amount of sulfur causes hot shortness and low duct-ility and therefore 0.5% is the upper limit of the sulfur content of the product disclosed herein.
Phosphorus at least 0.03%
Phosphorus is necessary for improving the smoothness of the surface finish. However, phosphorus can increase the work hardening and the hardness of the chip formed in machin-ing. Thus, the amount of phosphorus must be reduced from what is customary in bars of this type (usually up to 0.09~) to permit high speed machining operations in cold drawn steel bars with increased strength.
Columbium 0.01% to 0.10%
Columbium is essential in the pre~ent steel to increase strength, control the mechanical properties through the thickness of the bar and to reduce toughness of the chip.
The specification of columbium is different for different levels of yield strength and bar si~e. Columbium promotes hardenability and increases work hardening of the core in large diameter cold drawn bars. Columbium-bearing steel may be cold drawn with reduced draft in order to obtain minimal strengthening of the surface and substantial strengthening of the core. At a higher content than that specified, however, the effect of the columbium i8 to excessively increase strength and thereby reduce tool life.
Vanadium up to 0.1%
Vanadium provides for an increase of the surface-to-center mechanical properties of the steel bar and, in parti-cular, for large diameter cold drawn bars. As the vanadium content is inareased above that specified, the machinability characteri~tics of the bar deteriorate.
Residual elements up to 0.15%
The residual elements of nickel, chromium, molybde-num and copper are generally harmful for machinability because they increase strength and ductility and promote the formation of abrasive particles, all of which detract from the machina-bility characteristics of a steel. Thus, the residual ele-ments must be kept within the range specified.
The ratio of %Mn / %S should be from 1.6 to 4.0 and this ratio defines the amount of manganese in solid solution and the amount of FeS inclusions.
The relationship between manganese, sulfur and columbium specified as (%Mn - 1.62 X ~S) / ~Cb defines the relative contributions of manganese and columbium in strength-~ ., . . .,_ ,. _. _, .,, , _ _ . ,.__~
13~1489 ening the product. Manganese affects strength through chang-ing kinetics of austenite decomposition, whereas columbium decreases grain size and promotes precipitation hardening.
The ratios specified will vary depending on the size of the hot rolled product, the amount of draft involved in reducing to a cold drawn product and the desired tensile strength in the ultimate application of the steel bar.
In addition to the elements described, machinability is improved by the addition of one or more of the following:
lead in an amount, by weight, of 0.03% to 0.35%; ~irconium in an amount, by weight, of 0.005% to 0.05~; bismuth in an amount, by weight, of 0.05% to 0.25%; lead in an amount, by weight, of 0.03% to 0.15% and bismuth in an amount, by weight, of 0.05% to 0.15%; nitrogen in an amount, by weight, of 0.006%
to 0.012%; bismuth in an amount, by weight, of 0.05% to 0.25%
and tellurium in an amount, by weight, of 0.005% to 0.05%.
Zirconium maximizes machinability by promoting globular-shaped MnS inclusions, whereas nitrogen promotes the breakability of chips which facilitates drilling operations.
The following tables illustrate the relationship between the amounts of manganese, sulfur and columbium, and the hot rolled raw material, i.e. whether it be hot rolled coil, hot rolled bars up to two inches in diameter or a hot rolled bar having a diameter at least two inches. The tables provide an indication of the yield strength for particular products resulting from particular combinations of elements.
Table 1 illustrates the relationship between yield strength, percent manganese, percent columbium, percent sulur and the ratio of these three elements as applied to hot rolled coil designed to be formed into cold drawn bars with a range of yield strength from 60 to 80 ksi. Table 2 relates the speci-fication of manganese, sulfur and columbium for hot rolled :
~3C~1~8~t bars up to two inches and includes the effect on yield strength of the percent reduction in bar area in cold drawing.
Table 3 is similar to table 2 and provides the same informa-tion for hot rolled bars having a diameter at least two inches.
_g_ 3~1489 Specification of Mn, S and Cb for Hot Rolled Coil Designated to Cold Drawn Bars with a Range of Yield Strength of 60 to 80 ~8i ____________________________________________________________________ Yl~ld Man6~nen~ Columblum Sulfur Z Mn - 1,62-~5 Str~n~th,k~ 2 2 ~ -----~--------Z Cb ____________________________________________________________________ 0.010 13 to 25 0.65 0.25 to 0.32 0.020 6.. 5 to 12.5 0.010 23 t,o 35 0.7S 0.2S to 0.32 .
0.020 12.5 to 17.5 0.020 5 to 12.5 0.7d 0.2e to 0.35 `0 045 2 to 5 0.020 15 to 22.5 0.90 0.2~ to 0.35 0.045 6.5 to 10 0-035 ~ 3.5 to 7 0.75 0.30 to 0.3e 0.055 2.5 to 4.5 0.035 ~ 10 to 14.5 1.00 0.30 to 0.3e 0.055 . 7 to 9 0.060 6.5 to e.s eo 1.05 0.32 to 0.40 o.oeo s to 6 .
0.060 e to 10 eo 1.15 0.32 to 0.40 o.oeo 6 to e.s - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -13~14~g T~BLE 2 Specification of Mn, S and Cb for l~ot Rolled Bars up to 2" Designated to Cold Drawn Bars with a Range of Yield Strength of 60 to 80 ksi _________________________ ___________________________________________________ Yleld ~an~anen~ Columblum Sulfur %Mn - 1.627. S Reductlon Stren~th, ~ 7. ~ --__------------ ln k~l ~Cb Cold Drauln~,~
_____________________________________________________________________________ 0.010 13.3 to 25 60 0.70 0.28 to 0.35 S to 9 0.020 6.5 to lZ.5 0.010 33 to 45 60 0.90 0.28 to 0.35 4 to e 0.020 16.5 to 22.5 0.010 18 to 31 65 o.e . 0.30 to 0.3e 5 to ~0 0.020 9 to 15.5 0.010 38 to 51 6S 1.0 0.30 to 0.38 4 to 9 0.020 19 to 25.S
0.040 6.2 to 9.S
7 0.9 0.32 to 0.40 5 to 9 0.060 4.2 to 6.3 0.040 11.3 to 14.S
~O 1.1 0.32 to O.40 4 to e 0.060 7.5 to 9.7 o.O70 5.6 to 7.4 eo 1.l 0.36 to 0.44 5 to 10 0.090 4.3 to 5.~
0.070 e.4 to 10.3 ~0 1.3 0.36 to 0.44 4 to 0.090 6.6 to ~.0 __________________ ___________________________________________________________ . .
. :.. .......... . .
13~1489 Specification of Mn, S and Cb for Hot Rolled Bars at Least 2" Desig-nated to Cold Drawn Bars with a ~ange of Yield Strellgth of 60 to 80 ksi __________________________________________________________________________ Yleld Hancanese, Columblu~, Sulfur, 7Mn - 1.627.S Reduotlon Stren~th, % % ~ ------------ ln Cold ~81 ~Cb Drauln~,7.
__________________________________________________________________________.
0.020 9 to l5.7 o.e 0.30 to 0.3e 5 to 6 0,060 4.5 to 7.e 0.020 19 to 25.7 1.0 0.30 to 0.38 4 to 5 0.040 e.s to 12.
0.030 e.3 to 12.7 0.9 0.38 t~ 0.60 5 to 6 0-050 5 to 7.6 0-030 15 to 19.3 1.1 0.32 to 0.40 4 to 5 0-050 9 to 11.6 0.040 ll.Z to 14.5 1.1 0.32 to O.40 S to 6 0.060 7.5 to 9.7 0.040 16.3 to l9.S
~.3 0.32 to 0.40 4 to S
0.060 10.~ to 13 o.oeo . 6.1 to 7.e eo 1.2 0.36 eO 0.44 5 to 6 0.10 4.9 to 6.2 o.oeo e.6 to 10.3 eo ~.4 0.36 to 0.4~ 4 to 5 0.10 6.9 to ~.Z
_______________________________________________________________________ ~ , ~
: -12-. ~ ; .
:,~ .... .....
13()~4~
Further specific examples of products formed in accordance with the present invention are as follows.
Example 1: A hot rolled coil steel comprising:
C up to 0.06%
Mn 0.6% to 1.5 Si up to 0.1%
P 0.03% to 0.06%
S 0.25% to 0.40%
Cb 0.01% to 0.07%
The sum of Ni, Cr, Mo, and Cu up to 0.15%, with the balance iron. The ratio of (%Mn - 1.62 X %S) / %Cb is from 2.0 to 22.5 and the ratio percent %Mn / ~S is from 2.0 to 3.5.
The percent sulfur is further determined by multiplying the desired yield strength in ksi by (0.0042 - 0.0054).
Example 2: A hot rolled bar having a diameter up to two inches, comprising:
C up to 0.08%
Mn 0.7% to 1.30%
Si up to 0.1%
P 0.03% to 0.09%
S 0.28% to 0.50%
Cb 0.02% to 0.08%
V up to 0.1%
The sum of Ni, Cr, Mo, and Cu up to 0.15%, with the balance iron. The ratio of (%Mn - 1.62 X %S) / %Cb is from 4 to 51 and the ratio of %Mn / %S is from 2.0 to 3.2. The per-cent sulfur is further determined by multiplying the desired yield strength in ksi by (0.0045 - 0.0058).
Example 3: A hot rolled bar having a diameter at least two inches comprising:
C up to 0.08%
Mn 0.8% to 1.4%
Si up to 0.1%
p 0.03% to 0.9%
S 0.3% to 0.5%
Cb 0.02% to 0.10%
V up to 0.1%
The sum of Ni, Cr, Mo, and Cu up to 0.15%, with the balance iron. The ratio of (%Mn - 1.62 X %S) / %Cb being from S to 25 and the ratio of %Mn / %S is from 2.0 to 3.5. The ~3U14B9 percent sulfur is further determined by multiplying the desir-ed yield strength in ksi by ~0.0045 - 0.0063).
The percentages of manganese, sulfur and columbium increase, along with an increase in the desired yield strength of the product. The contribution of columbium into strength-ening the steel bar also increases with an increase in the target yield strength of the product. Excellent machinability in high speed drilling and forming is achieved using cold drawn bars with a yield strength of 60 to 65 ksi. Improved surface finish is achieved using cold drawn bars with a yield strength of 65 to 70 ksi.
An important aspect of the present invention resides in the fact that bars with different machining designations, capability and application may be selected from the range of the combination of mechanical and chemical properties disclos-ed herein. The percent reduction in cold drawing similarly has a substantial affect on yield strength. Yield strength directly relates to the percentage reduction in cold drawing, the type of hot rolled material used to form the bar, and the percentage of manganese, columbium and sulfur.
Whereas the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, alterations and substitutions thereto.
; -14-'.
: ', ~3~'1489 steel, resulfurized and rephosphorized steel, microalloyed steel and high-strength steel.
Another purpose is a cold drawn free-machining steel bar as described in which the amounts and ratios of manganese, sulfur and columbium and the amount and pattern of deformation in cold drawing are controlled to provide optimum machinabil-ity.
Other purposes will appear in the ensuing specifica-tion and claims.
DETAILED DESCRIPTION OF THE INVENTION
It is well-known that certain elements, such as sulfur, lead, bismuth, tellurium and selenium, are useful for improving machinability of steel. Machinability is a complex and not a fully understood property. The problem is one in which the effect of the alloy composition, plastic flow of the metal workpiece and cutting dynamics are not readily recogniz-ed from the manner in which the alloy is machined by cutting tools in such operations as single point turning, forming, drilling, reaming, boring, shaving and threading. There is a gap in the available knowledge of material behavior between test results obtained from conventional, non-steady-state tension experiments and results obtained from cutting force data derived from in-process machining.
Metallurgists have long sought to improve the mach-inability of free-machining steel bars by modifying the chemi-cal composition, optimizing size, shape, distribution and chemical composition of inclusions to enhance the brittleness of the chip and increase lubrication at the tool/chip inter-face. Further, it is desired to prevent formation of theabrasive particles and microconstituents which are in the steel bar. For example, for the purpose of improving 13~1489 machinability varying amounts of one or more such elements as bismuth and tellurium (U.S. Patent No. 4,236,939); lead, bis-muth and tellurium and/or sulfur (U.S. Patent No. 4,244,737);
tellurium and sulfur (U.S. Patent No. 4,279,646) have been included in resulfurized and rephosphorized free-machining steels. Such products, however, have not completely satisfied the need for increased machinability of free-machining steel.
Prior efforts at increasing machinability have been more specifically directed to the chemical composition rather than attempting to optimize the chemical composition, the draft or percentage size reduction in cold forming and the size and cross section of the bar. The present invention is specifi-cally directed to increasing machinability by combining the optimum ratio of chemical ingredients, particularly, manga-nese, sulfur and columbium with optimum size and cross sec-tions for the bar, as well as the amount of cold working.
Thus, in the present invention, the chemical composition, draft, size and cross section of a bar are tailored to meet particular machinability applications.
The cold drawn free-machining resulfurized and re-phosphorized steel bar of the present invention has a chemical composition, by weight, consisting of C up to 0.08%; Mn 0.6%
to 1.4%; Si up to 0.1%; P at least 0.3%; S 0.25% to 0.50%;
Cb 0.01% to 0.10%; V up to 0.1%; the sum of Ni, Cr, Mo, and Cu up to 0.15% with the balance being iron. The ratio of manga-nese, sulfur and columbium is particulary important in provid-ing a steel bar of the appropriate chemical characteristics and in predicting the yield strength of a particular bar.
Thus, the ratio of %Mn / %S is from 1.6 to 4.0 and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
The yield strength of the bar and, hence, its machinability is determined by the raw material, size and the , - 13~14B9 draft. The raw material may be, considering the available types of products from the mill, hot rolled coil, hot rolled bars up to two inches in diameter and hot rolled bars having a diameter of at least two inches. Such stock, after hot roll-ing to the specified size, and being cut off in appropriate lengths, will then be cold drawn and the draft or the size reduction in cold drawing is also extremely important in determining yield strength of the finished bar.
Carbon up to_0/08%
Considering the roles of the different chemical elements in the composition and their influence on machinabil-ity and performance of the steel, a reduced carbon content is essential for assuring low work hardening and strain hardening of a steel subject to cold drawing and machining. A low car-bon content providing low strength in a resulfurized and rephosphorized steel, when combined with the sum of residual elements, such as nickel, chromium, molybdenum and copper not exceeding 0.15%, provides a product of relatively low ductil-ity and increased breakability of the chip formed at the tool-workpiece interface. If the residual elements are in-creased above the level specified, with the reduced carbon content specified, the product has increased ductility and decreased breakability of the chip, which are disadvantageous in a free-machining product. Moreover, an increase in the carbon content above 0.08% increases the formation of abrasive particles, creates a likelihood of increased fracture stress and an increase of surface hardness, particularly in cold ~ drawn hexagonal bars.
; Manganese 0.6% to 1.4%
The specified amount of manganese is important for the formation of manganese sulfide (MnS) based inclusions which exert influence on tool life~ Manganese promotes hard-:
~3~489 enability and increases the strength of cold drawn bars. The The actual specification of manganese in a particular bar is dependent upon the diameter of the hot rolled steel, the re-quired mechanical properties for the bar and the machining designation. The manganese content i9 increased with an increase in the size of bar and an increase in the target level of yield strength.
Silicon up to 0.1%
The silicon content should be limited to 0.1% as an increased amount of silicon substantially increases the amount of abrasive silicates in the finished product.
Sulfur 0.25% to 0.50%
Sulfur is also necessary for the formation of MnS
inclusions, and it is for this reason that the sulfur content should be at least 0.25%. The particular specification of sulfur in a particular bar depends on the size of the bar and the manganese content. The minimal sulfur content is utilized with a hot rolled coil as the raw material, whereas the maxi-mum sulfur content is required for large diameter cold drawn bars with increased yield strength up to approximately 80 ksi.
An excess amount of sulfur causes hot shortness and low duct-ility and therefore 0.5% is the upper limit of the sulfur content of the product disclosed herein.
Phosphorus at least 0.03%
Phosphorus is necessary for improving the smoothness of the surface finish. However, phosphorus can increase the work hardening and the hardness of the chip formed in machin-ing. Thus, the amount of phosphorus must be reduced from what is customary in bars of this type (usually up to 0.09~) to permit high speed machining operations in cold drawn steel bars with increased strength.
Columbium 0.01% to 0.10%
Columbium is essential in the pre~ent steel to increase strength, control the mechanical properties through the thickness of the bar and to reduce toughness of the chip.
The specification of columbium is different for different levels of yield strength and bar si~e. Columbium promotes hardenability and increases work hardening of the core in large diameter cold drawn bars. Columbium-bearing steel may be cold drawn with reduced draft in order to obtain minimal strengthening of the surface and substantial strengthening of the core. At a higher content than that specified, however, the effect of the columbium i8 to excessively increase strength and thereby reduce tool life.
Vanadium up to 0.1%
Vanadium provides for an increase of the surface-to-center mechanical properties of the steel bar and, in parti-cular, for large diameter cold drawn bars. As the vanadium content is inareased above that specified, the machinability characteri~tics of the bar deteriorate.
Residual elements up to 0.15%
The residual elements of nickel, chromium, molybde-num and copper are generally harmful for machinability because they increase strength and ductility and promote the formation of abrasive particles, all of which detract from the machina-bility characteristics of a steel. Thus, the residual ele-ments must be kept within the range specified.
The ratio of %Mn / %S should be from 1.6 to 4.0 and this ratio defines the amount of manganese in solid solution and the amount of FeS inclusions.
The relationship between manganese, sulfur and columbium specified as (%Mn - 1.62 X ~S) / ~Cb defines the relative contributions of manganese and columbium in strength-~ ., . . .,_ ,. _. _, .,, , _ _ . ,.__~
13~1489 ening the product. Manganese affects strength through chang-ing kinetics of austenite decomposition, whereas columbium decreases grain size and promotes precipitation hardening.
The ratios specified will vary depending on the size of the hot rolled product, the amount of draft involved in reducing to a cold drawn product and the desired tensile strength in the ultimate application of the steel bar.
In addition to the elements described, machinability is improved by the addition of one or more of the following:
lead in an amount, by weight, of 0.03% to 0.35%; ~irconium in an amount, by weight, of 0.005% to 0.05~; bismuth in an amount, by weight, of 0.05% to 0.25%; lead in an amount, by weight, of 0.03% to 0.15% and bismuth in an amount, by weight, of 0.05% to 0.15%; nitrogen in an amount, by weight, of 0.006%
to 0.012%; bismuth in an amount, by weight, of 0.05% to 0.25%
and tellurium in an amount, by weight, of 0.005% to 0.05%.
Zirconium maximizes machinability by promoting globular-shaped MnS inclusions, whereas nitrogen promotes the breakability of chips which facilitates drilling operations.
The following tables illustrate the relationship between the amounts of manganese, sulfur and columbium, and the hot rolled raw material, i.e. whether it be hot rolled coil, hot rolled bars up to two inches in diameter or a hot rolled bar having a diameter at least two inches. The tables provide an indication of the yield strength for particular products resulting from particular combinations of elements.
Table 1 illustrates the relationship between yield strength, percent manganese, percent columbium, percent sulur and the ratio of these three elements as applied to hot rolled coil designed to be formed into cold drawn bars with a range of yield strength from 60 to 80 ksi. Table 2 relates the speci-fication of manganese, sulfur and columbium for hot rolled :
~3C~1~8~t bars up to two inches and includes the effect on yield strength of the percent reduction in bar area in cold drawing.
Table 3 is similar to table 2 and provides the same informa-tion for hot rolled bars having a diameter at least two inches.
_g_ 3~1489 Specification of Mn, S and Cb for Hot Rolled Coil Designated to Cold Drawn Bars with a Range of Yield Strength of 60 to 80 ~8i ____________________________________________________________________ Yl~ld Man6~nen~ Columblum Sulfur Z Mn - 1,62-~5 Str~n~th,k~ 2 2 ~ -----~--------Z Cb ____________________________________________________________________ 0.010 13 to 25 0.65 0.25 to 0.32 0.020 6.. 5 to 12.5 0.010 23 t,o 35 0.7S 0.2S to 0.32 .
0.020 12.5 to 17.5 0.020 5 to 12.5 0.7d 0.2e to 0.35 `0 045 2 to 5 0.020 15 to 22.5 0.90 0.2~ to 0.35 0.045 6.5 to 10 0-035 ~ 3.5 to 7 0.75 0.30 to 0.3e 0.055 2.5 to 4.5 0.035 ~ 10 to 14.5 1.00 0.30 to 0.3e 0.055 . 7 to 9 0.060 6.5 to e.s eo 1.05 0.32 to 0.40 o.oeo s to 6 .
0.060 e to 10 eo 1.15 0.32 to 0.40 o.oeo 6 to e.s - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -13~14~g T~BLE 2 Specification of Mn, S and Cb for l~ot Rolled Bars up to 2" Designated to Cold Drawn Bars with a Range of Yield Strength of 60 to 80 ksi _________________________ ___________________________________________________ Yleld ~an~anen~ Columblum Sulfur %Mn - 1.627. S Reductlon Stren~th, ~ 7. ~ --__------------ ln k~l ~Cb Cold Drauln~,~
_____________________________________________________________________________ 0.010 13.3 to 25 60 0.70 0.28 to 0.35 S to 9 0.020 6.5 to lZ.5 0.010 33 to 45 60 0.90 0.28 to 0.35 4 to e 0.020 16.5 to 22.5 0.010 18 to 31 65 o.e . 0.30 to 0.3e 5 to ~0 0.020 9 to 15.5 0.010 38 to 51 6S 1.0 0.30 to 0.38 4 to 9 0.020 19 to 25.S
0.040 6.2 to 9.S
7 0.9 0.32 to 0.40 5 to 9 0.060 4.2 to 6.3 0.040 11.3 to 14.S
~O 1.1 0.32 to O.40 4 to e 0.060 7.5 to 9.7 o.O70 5.6 to 7.4 eo 1.l 0.36 to 0.44 5 to 10 0.090 4.3 to 5.~
0.070 e.4 to 10.3 ~0 1.3 0.36 to 0.44 4 to 0.090 6.6 to ~.0 __________________ ___________________________________________________________ . .
. :.. .......... . .
13~1489 Specification of Mn, S and Cb for Hot Rolled Bars at Least 2" Desig-nated to Cold Drawn Bars with a ~ange of Yield Strellgth of 60 to 80 ksi __________________________________________________________________________ Yleld Hancanese, Columblu~, Sulfur, 7Mn - 1.627.S Reduotlon Stren~th, % % ~ ------------ ln Cold ~81 ~Cb Drauln~,7.
__________________________________________________________________________.
0.020 9 to l5.7 o.e 0.30 to 0.3e 5 to 6 0,060 4.5 to 7.e 0.020 19 to 25.7 1.0 0.30 to 0.38 4 to 5 0.040 e.s to 12.
0.030 e.3 to 12.7 0.9 0.38 t~ 0.60 5 to 6 0-050 5 to 7.6 0-030 15 to 19.3 1.1 0.32 to 0.40 4 to 5 0-050 9 to 11.6 0.040 ll.Z to 14.5 1.1 0.32 to O.40 S to 6 0.060 7.5 to 9.7 0.040 16.3 to l9.S
~.3 0.32 to 0.40 4 to S
0.060 10.~ to 13 o.oeo . 6.1 to 7.e eo 1.2 0.36 eO 0.44 5 to 6 0.10 4.9 to 6.2 o.oeo e.6 to 10.3 eo ~.4 0.36 to 0.4~ 4 to 5 0.10 6.9 to ~.Z
_______________________________________________________________________ ~ , ~
: -12-. ~ ; .
:,~ .... .....
13()~4~
Further specific examples of products formed in accordance with the present invention are as follows.
Example 1: A hot rolled coil steel comprising:
C up to 0.06%
Mn 0.6% to 1.5 Si up to 0.1%
P 0.03% to 0.06%
S 0.25% to 0.40%
Cb 0.01% to 0.07%
The sum of Ni, Cr, Mo, and Cu up to 0.15%, with the balance iron. The ratio of (%Mn - 1.62 X %S) / %Cb is from 2.0 to 22.5 and the ratio percent %Mn / ~S is from 2.0 to 3.5.
The percent sulfur is further determined by multiplying the desired yield strength in ksi by (0.0042 - 0.0054).
Example 2: A hot rolled bar having a diameter up to two inches, comprising:
C up to 0.08%
Mn 0.7% to 1.30%
Si up to 0.1%
P 0.03% to 0.09%
S 0.28% to 0.50%
Cb 0.02% to 0.08%
V up to 0.1%
The sum of Ni, Cr, Mo, and Cu up to 0.15%, with the balance iron. The ratio of (%Mn - 1.62 X %S) / %Cb is from 4 to 51 and the ratio of %Mn / %S is from 2.0 to 3.2. The per-cent sulfur is further determined by multiplying the desired yield strength in ksi by (0.0045 - 0.0058).
Example 3: A hot rolled bar having a diameter at least two inches comprising:
C up to 0.08%
Mn 0.8% to 1.4%
Si up to 0.1%
p 0.03% to 0.9%
S 0.3% to 0.5%
Cb 0.02% to 0.10%
V up to 0.1%
The sum of Ni, Cr, Mo, and Cu up to 0.15%, with the balance iron. The ratio of (%Mn - 1.62 X %S) / %Cb being from S to 25 and the ratio of %Mn / %S is from 2.0 to 3.5. The ~3U14B9 percent sulfur is further determined by multiplying the desir-ed yield strength in ksi by ~0.0045 - 0.0063).
The percentages of manganese, sulfur and columbium increase, along with an increase in the desired yield strength of the product. The contribution of columbium into strength-ening the steel bar also increases with an increase in the target yield strength of the product. Excellent machinability in high speed drilling and forming is achieved using cold drawn bars with a yield strength of 60 to 65 ksi. Improved surface finish is achieved using cold drawn bars with a yield strength of 65 to 70 ksi.
An important aspect of the present invention resides in the fact that bars with different machining designations, capability and application may be selected from the range of the combination of mechanical and chemical properties disclos-ed herein. The percent reduction in cold drawing similarly has a substantial affect on yield strength. Yield strength directly relates to the percentage reduction in cold drawing, the type of hot rolled material used to form the bar, and the percentage of manganese, columbium and sulfur.
Whereas the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, alterations and substitutions thereto.
; -14-'.
Claims (16)
1. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
2. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Pb 0.03% to 0.35%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Pb 0.03% to 0.35%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
3. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Zr 0.005% to 0.05%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Zr 0.005% to 0.05%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
4. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Bi 0.05% to 0.25%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Nn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Bi 0.05% to 0.25%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Nn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
5. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Nn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Pb 0.03% to 0.15%
Bi 0.05% to 0.15%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Nn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Pb 0.03% to 0.15%
Bi 0.05% to 0.15%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
6. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
N 0.006% to 0.012%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
N 0.006% to 0.012%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
7. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Bi 0.05% to 0.25%
Te 0.005% to 0.05%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Mn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Bi 0.05% to 0.25%
Te 0.005% to 0.05%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
8. The cold drawn steel bar of claim 1 further characterized in that the amount of Cb is from 0.01% to 0.04% and the bar has a yield strength of approximately 60 ksi.
9. The cold drawn steel bar of claim 1 further characterized in that the amount of Cb is from 0.02% to 0.06% and the bar has a yield strength of approximately 65 ksi.
10. The cold drawn steel bar of claim 1 further characterized in that the amount of Cb is from 0.02% to 0.07% and the bar has a yield strength of approximately 70 ksi.
11. The cold drawn steel bar of claim 1 further characterized in that the amount of Cb is from 0.06% to 0.1% and the bar has a yield strength of approximately 80 ksi.
12. A cold drawn rephosphorized and resulfurized free-machining steel bar formed from a hot rolled steel coil having the composition, by weight:
C up to 0.06%
Mn 0.6% to 1.15%
Si up to 0.1%
P 0.03% to 0.06%
S 0.25% to 0.40%
Cb 0.01% to 0.07%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 2.0 to 3.5, the ratio of (%Nn - 1.62 X %S) / %Cb is from 2 to 50, and %S = (0.0042 - 0.0054) X the desired yield strength in ksi.
C up to 0.06%
Mn 0.6% to 1.15%
Si up to 0.1%
P 0.03% to 0.06%
S 0.25% to 0.40%
Cb 0.01% to 0.07%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 2.0 to 3.5, the ratio of (%Nn - 1.62 X %S) / %Cb is from 2 to 50, and %S = (0.0042 - 0.0054) X the desired yield strength in ksi.
13. The cold drawn steel bar of claim 1 further characterized in that the reduction in area in cold drawing is from 15% to 30% of the hot rolled bar, with the bar having a yield strength of from 60 to 80 ksi.
14. A cold drawn rephosphorized and resulfurized free-machining steel bar formed by hot rolling a bar up to two inches in cross section, the steel bar having the composition, by weight:
C up to 0.08%
Mn 0.7% to 1.30%
Si up to 0.1%
P 0.03% to 0.09%
S 0.28% to 0.50%
Cb 0.02% to 0.08%
V up to 0.1%
the sum of Ni, Cr, No, and Cu up to 0.15%, balance iron, the ratio of %Nn / %S is from 2.0 to 3.2, the ratio (%Mn - 1.62 X %S) / %Cb is from 4 to 51, and %S = (0.0045 - 0.0058) X the desired yield strength in ksi.
C up to 0.08%
Mn 0.7% to 1.30%
Si up to 0.1%
P 0.03% to 0.09%
S 0.28% to 0.50%
Cb 0.02% to 0.08%
V up to 0.1%
the sum of Ni, Cr, No, and Cu up to 0.15%, balance iron, the ratio of %Nn / %S is from 2.0 to 3.2, the ratio (%Mn - 1.62 X %S) / %Cb is from 4 to 51, and %S = (0.0045 - 0.0058) X the desired yield strength in ksi.
15. A cold drawn rephosphorized and resulfurized free-machining steel bar formed of a hot rolled bar at least two inches in cross section, the steel having the composition, by weight:
C up to 0.08%
Mn 0.8% to 1.4%
Si up to 0.1%
P 0.03% to 0.9%
S 0.30% to 0.50%
Cb 0.02% to 0.10%
V up to 0.1%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio %Mn / %S is from 2.0 to 3.5, the ratio (%Mn - 1.62 X %S) / %Cb is from 5 to 25, and %S = (0.0045 - 0.0063) X the desired yield strength in ksi.
C up to 0.08%
Mn 0.8% to 1.4%
Si up to 0.1%
P 0.03% to 0.9%
S 0.30% to 0.50%
Cb 0.02% to 0.10%
V up to 0.1%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio %Mn / %S is from 2.0 to 3.5, the ratio (%Mn - 1.62 X %S) / %Cb is from 5 to 25, and %S = (0.0045 - 0.0063) X the desired yield strength in ksi.
16. A cold drawn resulfurized and rephosphorized free-machining steel bar having the composition, by weight:
C up to 0.08%
Nn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Pb 0 to 0.35%
Zr 0 to 0.05%
Bi 0 to 0.25%
N 0 to 0.012%
Te 0 to 0.05%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
C up to 0.08%
Nn 0.6% to 1.4%
Si up to 0.1%
P at least 0.03%
S 0.25% to 0.50%
Cb 0.01% to 0.10%
V up to 0.1%
Pb 0 to 0.35%
Zr 0 to 0.05%
Bi 0 to 0.25%
N 0 to 0.012%
Te 0 to 0.05%
the sum of Ni, Cr, Mo, and Cu up to 0.15%, balance iron, the ratio of %Mn / %S is from 1.6 to 4.0, and the ratio of (%Mn - 1.62 X %S) / %Cb is from 2 to 50.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US87254486A | 1986-06-10 | 1986-06-10 | |
| US872,544 | 1986-06-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1301489C true CA1301489C (en) | 1992-05-26 |
Family
ID=25359800
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000538742A Expired - Fee Related CA1301489C (en) | 1986-06-10 | 1987-06-03 | Cold drawn free-machining resulfurized and rephosphorized steel bars having controlled mechanical properties and controlled machinability |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPH062928B2 (en) |
| KR (1) | KR880000615A (en) |
| BR (1) | BR8702911A (en) |
| CA (1) | CA1301489C (en) |
| DE (1) | DE3718772C2 (en) |
| FR (1) | FR2601697B1 (en) |
| GB (1) | GB2191506B (en) |
| IT (1) | IT1206025B (en) |
| MX (1) | MX168196B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6395109B1 (en) | 2000-02-15 | 2002-05-28 | Cargill, Incorporated | Bar product, cylinder rods, hydraulic cylinders, and method for manufacturing |
| JP3929029B2 (en) | 2002-03-12 | 2007-06-13 | 三菱製鋼株式会社 | Sulfur-containing free-cutting steel |
| US7488396B2 (en) | 2002-11-15 | 2009-02-10 | Nippon Steel Corporation | Superior in machinability and method of production of same |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3424576A (en) * | 1968-04-23 | 1969-01-28 | Lukens Steel Co | Free machining steels |
| US3634073A (en) * | 1969-07-09 | 1972-01-11 | United States Steel Corp | Free-machining steel, articles thereof and method of making |
| ZA75241B (en) * | 1974-08-14 | 1976-01-28 | Inland Steel Co | Leaded steel bar |
| JPS55138064A (en) * | 1979-04-10 | 1980-10-28 | Daido Steel Co Ltd | Free-cutting steel having excellent rolling fatigue strength |
| DE3009491A1 (en) * | 1979-03-14 | 1980-09-25 | Daido Steel Co Ltd | STEEL FOR COLD FORGING AND METHOD FOR THE PRODUCTION THEREOF |
| DE3018537A1 (en) * | 1979-05-17 | 1980-11-27 | Daido Steel Co Ltd | CONTROLLED INCLUDING AUTOMATIC STEEL AND METHOD FOR THE PRODUCTION THEREOF |
| DE2967319D1 (en) * | 1979-06-08 | 1985-01-17 | Henrik Giflo | High-strength freely machinable steel capable of sustaining dynamic forces |
| JPS62270752A (en) * | 1986-05-19 | 1987-11-25 | Daido Steel Co Ltd | Free-cutting steel excellent in property of nitriding |
-
1987
- 1987-06-03 CA CA000538742A patent/CA1301489C/en not_active Expired - Fee Related
- 1987-06-04 DE DE3718772A patent/DE3718772C2/en not_active Expired - Fee Related
- 1987-06-05 GB GB8713199A patent/GB2191506B/en not_active Expired - Fee Related
- 1987-06-09 BR BR8702911A patent/BR8702911A/en unknown
- 1987-06-09 KR KR870005837A patent/KR880000615A/en not_active Application Discontinuation
- 1987-06-09 FR FR878707998A patent/FR2601697B1/en not_active Expired
- 1987-06-09 IT IT8748036A patent/IT1206025B/en active
- 1987-06-10 JP JP62143441A patent/JPH062928B2/en not_active Expired - Lifetime
- 1987-06-10 MX MX006853A patent/MX168196B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| IT8748036A0 (en) | 1987-06-09 |
| JPH062928B2 (en) | 1994-01-12 |
| IT1206025B (en) | 1989-04-05 |
| GB8713199D0 (en) | 1987-07-08 |
| KR880000615A (en) | 1988-03-28 |
| DE3718772A1 (en) | 1987-12-17 |
| MX168196B (en) | 1993-05-11 |
| FR2601697B1 (en) | 1989-08-11 |
| GB2191506B (en) | 1990-01-04 |
| DE3718772C2 (en) | 1994-02-17 |
| JPS63441A (en) | 1988-01-05 |
| BR8702911A (en) | 1988-03-08 |
| GB2191506A (en) | 1987-12-16 |
| FR2601697A1 (en) | 1988-01-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |