US3860457A - A ductile iron and method of making it - Google Patents
A ductile iron and method of making it Download PDFInfo
- Publication number
- US3860457A US3860457A US377035A US37703573A US3860457A US 3860457 A US3860457 A US 3860457A US 377035 A US377035 A US 377035A US 37703573 A US37703573 A US 37703573A US 3860457 A US3860457 A US 3860457A
- Authority
- US
- United States
- Prior art keywords
- ductile iron
- weight
- molybdenium
- iron
- bainite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229910001141 Ductile iron Inorganic materials 0.000 title claims abstract description 58
- 238000004519 manufacturing process Methods 0.000 title description 3
- 238000005275 alloying Methods 0.000 claims abstract description 18
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 14
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 13
- 239000010949 copper Substances 0.000 claims abstract description 12
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052802 copper Inorganic materials 0.000 claims abstract description 10
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052718 tin Inorganic materials 0.000 claims abstract description 9
- 238000010791 quenching Methods 0.000 claims abstract description 6
- 230000000171 quenching effect Effects 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 13
- 239000011572 manganese Substances 0.000 claims description 10
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 8
- 238000003754 machining Methods 0.000 claims description 8
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 230000000717 retained effect Effects 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 abstract description 14
- 238000005266 casting Methods 0.000 abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 9
- 229910052759 nickel Inorganic materials 0.000 abstract description 7
- 230000015572 biosynthetic process Effects 0.000 abstract description 6
- 229910052742 iron Inorganic materials 0.000 abstract description 5
- 229910001562 pearlite Inorganic materials 0.000 abstract description 4
- 238000009661 fatigue test Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 229920001074 Tenite Polymers 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- -1 ferritepearlite Inorganic materials 0.000 description 1
- 235000000396 iron Nutrition 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000004848 polyfunctional curative Substances 0.000 description 1
- 235000010333 potassium nitrate Nutrition 0.000 description 1
- 239000004323 potassium nitrate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000011135 tin Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
Definitions
- said iron UNITED STATES PATENTS contains molybdenium 0.15 0.22 by weight and 2,324,322 7/1943 Reese et a1.
- 148/35 X less than 0.2 by weight of tin and/or less than 1.0 2,485,760 /1949 Millis et al across 75/123 CB by weight of copper.
- the present invention relates to a ductile iron alloyed with molybdenium and manganese and which has, after an isothermal heat treatment, a bainitic microstructure with a considerable amount of retained austenite.
- Ductile iron is generally used unalloyed or alloyed in various ways, and with, for example, a ferrite, ferritepearlite, pearlite, annealed martensite, or bainitic microstructure.
- the most essential characteristic of the ductile iron according to the present invention is its bainitic microstructure in combination with a considerable amount of retained austenite.
- FIG. 1 shows an example of such a ductile iron; the S-curves are indicated by solid lines and the curve which illustrates the cooling of the piece by a broken line in the time-temperature coordiate system.
- a bainitizing process in which pieces manufactured from unalloyed ductile iron are heattreated isothermally.
- the cast piece is reheated to the austenitization temperature after the casting process and is then cooled rapidly in a hot bath at an appropriate temperature.
- the piece is kept in the bath and thereby at a constant temperature until the bainite reaction has taken place, whereafter the piece is cooled to room temperature.
- the S-curves according to this process are indicated by solid lines and the curve illustrating the cooling of the piece by a broken line in a time-temperature coordiate system.
- the present invention provides a ductile iron of the character described, which comprises as alloying elements molybdenium 0.10 0.26 by weight and manganese 0.3 1.4 by weight and possibly also an alloying'element which promotes the formation of a pearlitic micro-structure during the casting and thereby accelerates the austenization and which consists of nickel in an amount of less than 2.5 by weight and at least one of the elements tin and copper.
- the ductile iron and its bainitization process according to the present invention can be applied to both thick and thin castings. In this process, the alloying ratios need not be changed according to the wall thickness of the casting.
- This ductile iron is rather mildly alloyed so that the alloying elements do not raise its price very much.
- the retained austenite present in this ductile iron in addition to bainite, gives it toughness and makes it capable of being hardened by machining.
- Hardening by machining creates a compression stress at the surface and thereby increases the fatigue strength. Its elongation at rupture is great.
- the ductile iron according to the invention contains the conventional amounts of carbon, silicon, phosphorus, sulphur, and magnesium, and as actual alloying elements, molybdenium 0.10 0.26 preferably 0.15 0.22 and manganese 0.3 1.4
- a ductile iron so alloyed is as such suitable for isothermal bainitization. If an amount of 0.03 0.2 of tin, 0.3 1.0 of copper, or 0.5 2.5 of nickel is also added to the alloy, a pearlitic micro-structure is obtained in the piece in as cast condition, and when this structure is reheated to the austenitization temperature, itbecomcs austenitized considerably faster than a micro-structure which contains free ferrite, and thereby the heattreatment period is shortened. Tin, copper and nickel have a similar effect on the pearlite formation and therefore they can entirely or partly replace each other; for example, a one-third batch of each of the three additives can be used.
- a ductile iron according to the invention, bainitized isothermally, is an excellent raw material for gears, especially when the teeth cannot be finishedor are not worth finishing by grinding.
- An example of such a case is gears with inside teeth. It is also applicable to all kinds of machine elements exposed to fatigue stress loads. Examples of such machine elements are, in addition to gears, gear shafts, sprockets, support wheels or rolls which are to roll against a hard surface, cams, crankshafts, support rings, and various parts subject to wear and tear, such as friction plates.
- FIG. 1 shows, in time-temperature diagram, some characteristical curves for a highly alloyed ductile iron belonging to the prior art
- FIG. 2 shows corresponding curves for a known unalloyed ductile iron
- FIG. 3 shows corresponding curves for a ductile iron according to the present invention.
- a ductile iron piece according to the invention is manufactured, for example, in the following manner: A disk-shaped blank with a diameter of 150 mm and a thickness of mm is cast from a melt which contains as alloying elements carbon (C) 3.5 3.7 silicon (Si) 2.1 2.4 manganese (Mn) 0.50 0.55 molybdenium (M0) 0.2 0.22 and copper (Cu) 0.7 0.8 and a conventional amount of magnesium.
- the blank is allowed to cool freely, or its treatment is continued while it is hot.
- the blank is transferred to a furnace with a temperature of 900C. In the furnace, the micro-structure of the blank is transformed into austenite.
- the blank After an austenitization of 2 hours, the blank is quenched into a salt bath at a temperature of 370C.
- the quantity of the bath is 200 kg and it contains 1 part of sodium nitrate (NaNO and 1 part of potassium nitrate (KNO).
- the bath has been provided with a agitation device and with a thermostat.
- the test piece is kept in the bath from minutes to 4 hours, depending on the desired amount of bainite.
- the blank is removed from the bath and allowed to cool freely. Thereafter, the blank contains, for example, bainite about 50 by vol., austenite about 40 by vol., and graphite about 10 by vol.
- a suitable amount of retained austenite is -50 by vol.
- a ductile iron containing less austenite is not capable of being work hardened by machining and a ductile iron containing more austenite is not strong enough.
- FIG. 3 The isothermal heat-treatment of a ductile iron according to the invention is illustrated in FIG. 3 in a time-temperature coordinate system.
- the solid lines indicate the S-curves of the ductile iron.
- the broken line indicates the cooling curve of the piece.
- An isothermally bainitized blank, cast from a ductile iron alloyed according to the invention, is of a very even qualityand suitable for machining. It has been verified by tensile strength tests that its elongation, when a tensile strength of 1 10 kp/mm is used, is about 10 which is high when compared to the respective value of a highly alloyed bainitic ductile iron or a quenched and tempered ductile iron of the same strength.
- the tensile strength and elongation of some bainitized ductile irons having an alloy ratio according to the present invention are as follows:
- the retained austenite in a ductile iron according to the invention makes it capable of being hardened by machining and thereby capable of enduring a very fatiguing load.
- a bending fatigue test with a turned and polished test bar of 12 mm gives a value of 50 kp/mm which is high compared to the respective values of other ductile iron.
- a bending fatigue test with a notch bar of 12 mm into which there has been turned a groove with an angle of 60 and with a bottom rounding radius of 1.0 mm gives a value of 40 kplmm which is high even when compared to steels.
- the ratio of the values obtained from fatigue tests with the same SG- iron i.e., the ratio of the smooth bar value 50 kp/mm to the value 40 kp/mm of the notched bar, namely, 1.25, called the notch effect, is very low.
- Rolling fatigue tests with a ductile iron according to the invention gave the following values.
- the composition of the SG-iron used in the test was: C 3.66 Si 2.24 Mn 0.54 Mo 0.22 Cu 0.78 P 0.02 and S 0.008 It was heat-treated so that the micro-structure contained bainite about 53 by vol., austenite about 37 by ml, and graphite about 10 by vol.
- the Hertzian contact stress was determined in a rotary fatigue test and was comparable to the values given in DIN 3990 El 9.
- the counter gear was case-hardened steel (DIN 1720, 15CrNi6) with surface hardeners 58-68 HRC.
- a ductile iron especially applicable to machine elements exposed to fatigue stresses containing as alloying elements molybdenium 0.10-0.26 per cent by weight and manganese 0.3-1.4 per cent by weight and having a microstructure of isothermal bainite and 20 to' 50% by volume of retained austenite enabling work hardening of the ductile iron in use when exposed to said fatigue stresses or by machining.
- a ductile iron as in claim 1 containing tin up to 0.2% by weight.
- a ductile iron as in claim 1 containing copper up to 1.0% by weight.
- a method of producing an austenitic-bainitic ductile iron comprising austenitizing a ductile iron containing as alloying elements molybdenium 0.10-0.26 per cent by weight and manganese 0.3-l.4 per cent by weight by heating it to the austenitization temperature and austenitizing it, then quenching it in a hot bath to form isothermal bainite, and cooling it further when the bainitic ductile iron so transformed still contains 20 to 50% by volume of retained austenite.
- a method as in claim 5 including machining the ductile iron before quenching it.
- a machine element constructed of the ductile iron ofclaiml.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
For a ductile iron of the type which has been heated, after casting, to its austenization temperature and austenized and subsequently heat-treated isothermally by quenching in a hot bath to start a bainite reaction which is continued until a desired fraction of the austenite have formed into bainite, improved properties are achieved by adding as alloying elements molybdenium 0.10 - 0.26 % and magnanese 0.3 - 1.4 % by weight and preferably also an additional alloying element which promotes the formation of a pearlite micro-structure during casting and, consequently, accelerates the austenization, said additional element consisting of nickel in an amount less than 2.5 % by weight, and tin and/or copper. Preferably said iron contains molybdenium 0.15 - 0.22 % by weight and less than 0.2 % by weight of tin and/or less than 1.0 % by weight of copper.
Description
United States Patent Vourinen et al.
1111 3,860,457 1 Jan. 14, 1975 1 A DUCTILE IRON AND METHOD OF MAKING IT [75] inventors: Jouko Vourinen; Yrjii Ingman;
Matti Johansson, all of Karkkila; OTHER. PUBLICATIONS Martti Kurkinen, Tapiola, all of Iron & Steel, Feb. 1970, page 5360. Finland Primary Examiner-C. Lovell [73] Assignee. Kymm Osakeyhtio-Kymmene Akfiebolag Kuusankoski, Finland Attorney, Agent, or Firm-Cushman, Darby, Cushman [22] Filed: July 6, 1973 [57] ABSTRACT PP N03 377,035 For a ductile iron of the type which has been heated, after casting, to its austenization temperature and austenized and subsequently heat-treated isothermally [30] Foreign Application Pnomy Data by quenching in a hot bath to start a bainite reaction July 12, 1972 F nland 1996/72 which is Continued until a desired fraction f h July 12, l972 Finland 1997/72 tenite v formed into i i i p d p p i are achieved by adding as alloying elements molyb- [52] U.S. Cl. 148/15, 75l/lltgilglll44s8/ll345l, denium (H 0'26 and magnanese 03 L4 by weight and preferably also an additional alloying ele- [511 E Czld 1/46 Czld 5/00 C22C 37/04 ment which promotes the formation of a pearlite mi- [58] d o earch l cro-structure during casting and, consequently, accel- 75/123 CB erates the austenization, said additional element consisting of nickel in an amount less than 2.5 by [56] References C'ted weight, and tin and/or copper. Preferably said iron UNITED STATES PATENTS contains molybdenium 0.15 0.22 by weight and 2,324,322 7/1943 Reese et a1. 148/35 X less than 0.2 by weight of tin and/or less than 1.0 2,485,760 /1949 Millis et al..... 75/123 CB by weight of copper. 3,549,430 12/1970 Kies et al 148/35 3,549,431 12 1970 de Castelet 148/35 x 7 Clalms, 3 Drawmg Figures M K a 5 0 5 60 mo 50B /000m/n.
FOREIGN PATENTS OR APPLICATIONS 4/1964 Great Britain 1. /123 CB A DUCTILE IRON AND METHOD OF MAKING IT BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a ductile iron alloyed with molybdenium and manganese and which has, after an isothermal heat treatment, a bainitic microstructure with a considerable amount of retained austenite.
Ductile iron is generally used unalloyed or alloyed in various ways, and with, for example, a ferrite, ferritepearlite, pearlite, annealed martensite, or bainitic microstructure.
The most essential characteristic of the ductile iron according to the present invention is its bainitic microstructure in combination with a considerable amount of retained austenite.
Previously known is a process for bainitizing ductile or SG-iron; in this process the bainite reaction is obtained in a highly alloyed ductile iron in connection with cooling immediately after casting. Such a ductile iron is introduced in US. Pat. application Ser. No. 682,985 and German Federal Republic Pat. application 1,808,515. FIG. 1 shows an example of such a ductile iron; the S-curves are indicated by solid lines and the curve which illustrates the cooling of the piece by a broken line in the time-temperature coordiate system. Under the influence of the alloying elements the S- curves have moved considerably to the right from where they would be in an unalloyed ductile iron and, thus, owing to the high degree of alloying, bainite is obtained in connection with the cooling. In addition to molybdenium, a great amount of nickel (3.2 7.0 is used as an alloying element. By this process, a bainitic micro-structure is obtained in pieces with even thick walls, but it has disadvantages in the high price caused by the alloying and, especially, in that the alloying ratios must be determined according to the wall thickness of each given piece to be cast.
Also known is a bainitizing process in which pieces manufactured from unalloyed ductile iron are heattreated isothermally. In this heat-treatment, the cast piece is reheated to the austenitization temperature after the casting process and is then cooled rapidly in a hot bath at an appropriate temperature. The piece is kept in the bath and thereby at a constant temperature until the bainite reaction has taken place, whereafter the piece is cooled to room temperature. In FIG. 2, the S-curves according to this process are indicated by solid lines and the curve illustrating the cooling of the piece by a broken line in a time-temperature coordiate system. By this-process, a bainitic micro-structure is obtained in a ductile iron which does not contain expensive elements. The rapid cooling required by this process is possible only with thin-walled castings. The greatest suitable thickness of material is about 20 mm.
SUMMARY OF THE INVENTION The present invention provides a ductile iron of the character described, which comprises as alloying elements molybdenium 0.10 0.26 by weight and manganese 0.3 1.4 by weight and possibly also an alloying'element which promotes the formation of a pearlitic micro-structure during the casting and thereby accelerates the austenization and which consists of nickel in an amount of less than 2.5 by weight and at least one of the elements tin and copper.
The ductile iron and its bainitization process according to the present invention can be applied to both thick and thin castings. In this process, the alloying ratios need not be changed according to the wall thickness of the casting.
This ductile iron is rather mildly alloyed so that the alloying elements do not raise its price very much. In addition, the retained austenite present in this ductile iron, in addition to bainite, gives it toughness and makes it capable of being hardened by machining.
Hardening by machining creates a compression stress at the surface and thereby increases the fatigue strength. Its elongation at rupture is great.
Thus the ductile iron according to the invention contains the conventional amounts of carbon, silicon, phosphorus, sulphur, and magnesium, and as actual alloying elements, molybdenium 0.10 0.26 preferably 0.15 0.22 and manganese 0.3 1.4 A ductile iron so alloyed is as such suitable for isothermal bainitization. If an amount of 0.03 0.2 of tin, 0.3 1.0 of copper, or 0.5 2.5 of nickel is also added to the alloy, a pearlitic micro-structure is obtained in the piece in as cast condition, and when this structure is reheated to the austenitization temperature, itbecomcs austenitized considerably faster than a micro-structure which contains free ferrite, and thereby the heattreatment period is shortened. Tin, copper and nickel have a similar effect on the pearlite formation and therefore they can entirely or partly replace each other; for example, a one-third batch of each of the three additives can be used.
A ductile iron according to the invention, bainitized isothermally, is an excellent raw material for gears, especially when the teeth cannot be finishedor are not worth finishing by grinding. An example of such a case is gears with inside teeth. It is also applicable to all kinds of machine elements exposed to fatigue stress loads. Examples of such machine elements are, in addition to gears, gear shafts, sprockets, support wheels or rolls which are to roll against a hard surface, cams, crankshafts, support rings, and various parts subject to wear and tear, such as friction plates.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows, in time-temperature diagram, some characteristical curves for a highly alloyed ductile iron belonging to the prior art;
FIG. 2 shows corresponding curves for a known unalloyed ductile iron; and
FIG. 3 shows corresponding curves for a ductile iron according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS A ductile iron piece according to the invention is manufactured, for example, in the following manner: A disk-shaped blank with a diameter of 150 mm and a thickness of mm is cast from a melt which contains as alloying elements carbon (C) 3.5 3.7 silicon (Si) 2.1 2.4 manganese (Mn) 0.50 0.55 molybdenium (M0) 0.2 0.22 and copper (Cu) 0.7 0.8 and a conventional amount of magnesium. The blank is allowed to cool freely, or its treatment is continued while it is hot. The blank is transferred to a furnace with a temperature of 900C. In the furnace, the micro-structure of the blank is transformed into austenite. After an austenitization of 2 hours, the blank is quenched into a salt bath at a temperature of 370C. The quantity of the bath is 200 kg and it contains 1 part of sodium nitrate (NaNO and 1 part of potassium nitrate (KNO The bath has been provided with a agitation device and with a thermostat. The test piece is kept in the bath from minutes to 4 hours, depending on the desired amount of bainite. The blank is removed from the bath and allowed to cool freely. Thereafter, the blank contains, for example, bainite about 50 by vol., austenite about 40 by vol., and graphite about 10 by vol. A suitable amount of retained austenite is -50 by vol. A ductile iron containing less austenite is not capable of being work hardened by machining and a ductile iron containing more austenite is not strong enough.
The isothermal heat-treatment of a ductile iron according to the invention is illustrated in FIG. 3 in a time-temperature coordinate system. The solid lines indicate the S-curves of the ductile iron. The broken line indicates the cooling curve of the piece.
An isothermally bainitized blank, cast from a ductile iron alloyed according to the invention, is of a very even qualityand suitable for machining. It has been verified by tensile strength tests that its elongation, when a tensile strength of 1 10 kp/mm is used, is about 10 which is high when compared to the respective value of a highly alloyed bainitic ductile iron or a quenched and tempered ductile iron of the same strength.
The tensile strength and elongation of some bainitized ductile irons having an alloy ratio according to the present invention are as follows:
If less than 0.10 of molybdenium is present bainitization will not take place in thick bodies, and if it is present in an amount exceeding 0.26 the formation of carbides increases and so does the price.
If the manganese content exceeds 1.4 the risk of carbide formation increases and the austenization time gets longer.
If the nickel content exceeds 2.5 the price of the iron is uselessly high.
The retained austenite in a ductile iron according to the invention makes it capable of being hardened by machining and thereby capable of enduring a very fatiguing load. A bending fatigue test with a turned and polished test bar of 12 mm gives a value of 50 kp/mm which is high compared to the respective values of other ductile iron. A bending fatigue test with a notch bar of 12 mm into which there has been turned a groove with an angle of 60 and with a bottom rounding radius of 1.0 mm gives a value of 40 kplmm which is high even when compared to steels. The ratio of the values obtained from fatigue tests with the same SG- iron, i.e., the ratio of the smooth bar value 50 kp/mm to the value 40 kp/mm of the notched bar, namely, 1.25, called the notch effect, is very low.
Rolling fatigue tests with a ductile iron according to the invention gave the following values. The composition of the SG-iron used in the test was: C 3.66 Si 2.24 Mn 0.54 Mo 0.22 Cu 0.78 P 0.02 and S 0.008 It was heat-treated so that the micro-structure contained bainite about 53 by vol., austenite about 37 by ml, and graphite about 10 by vol. The Hertzian contact stress was determined in a rotary fatigue test and was comparable to the values given in DIN 3990 El 9. The test gears were machined, their module 3.5, tooth number =33, slant angle 15, and width 45 mm. The counter gear was case-hardened steel (DIN 1720, 15CrNi6) with surface hardeners 58-68 HRC. The tooth number of the counter wheel=65. Values 132, 138, and kp/mm were obtained with the test wheels. These values are more than double the respective values given for the strongest ductile iron in DIN 3990 B1 9. The test results indicate how well the ductile iron according to the invention is applicable to rotary fatigue, i.e., it can be loaded with a considerable surface pressure without pitting damage.
What is claimed is:
l. A ductile iron especially applicable to machine elements exposed to fatigue stresses, containing as alloying elements molybdenium 0.10-0.26 per cent by weight and manganese 0.3-1.4 per cent by weight and having a microstructure of isothermal bainite and 20 to' 50% by volume of retained austenite enabling work hardening of the ductile iron in use when exposed to said fatigue stresses or by machining.
2. A ductile iron as in claim 1 wherein the molybdenium content is 0.15-0.22% by weight.
3. A ductile iron as in claim 1 containing tin up to 0.2% by weight.
4. A ductile iron as in claim 1 containing copper up to 1.0% by weight.
5. A method of producing an austenitic-bainitic ductile iron, comprising austenitizing a ductile iron containing as alloying elements molybdenium 0.10-0.26 per cent by weight and manganese 0.3-l.4 per cent by weight by heating it to the austenitization temperature and austenitizing it, then quenching it in a hot bath to form isothermal bainite, and cooling it further when the bainitic ductile iron so transformed still contains 20 to 50% by volume of retained austenite.
6. A method as in claim 5 including machining the ductile iron before quenching it.
7. A machine element constructed of the ductile iron ofclaiml.
RUTH C. MASOI? Attesting Officer Patent No. 1 1 7 Jana l4 Inventor(s) Jouko VUORINEN; Yrjo INGMAN; Matti JOHANSSON; and
Martti KURKINEN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
' On the front page format, please correct the spelling of -Jouko Vu o-rineneach occurrenceo Signed and sealed this 10th day of June 1975.
(SEAL) Attest:
C. MARSHALL DANN Commissioner of Patents and Trademarks
Claims (6)
- 2. A ductile iron as in claim 1 wherein the molybdenium content is 0.15-0.22% by weight.
- 3. A ductile iron as in claim 1 containing tin up to 0.2% by weight.
- 4. A ductile iron as in claim 1 containing copper up to 1.0% by weight.
- 5. A method of producing an austenitic-bainitic ductile iron, comprising austenitizing a ductile iron containing as alloying elements molybdenium 0.10-0.26 per cent by weight and manganese 0.3-1.4 per cent by weight by heating it to the austenitization temperature and austenitizing it, then quenching it in a hot bath to form isothermal bainite, and cooling it further when the bainitic ductile iron so transformed still contains 20 to 50% by volume of retained austenite.
- 6. A method as in claim 5 including machining the ductile iron before quenching it.
- 7. A machine element constructed of the ductile iron of claim 1.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI199672A FI49732C (en) | 1972-07-12 | 1972-07-12 | Alloyed SG iron. |
FI199772 | 1972-07-12 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3860457A true US3860457A (en) | 1975-01-14 |
Family
ID=26156551
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US377035A Expired - Lifetime US3860457A (en) | 1972-07-12 | 1973-07-06 | A ductile iron and method of making it |
Country Status (11)
Country | Link |
---|---|
US (1) | US3860457A (en) |
JP (1) | JPS553422B2 (en) |
CA (1) | CA1016372A (en) |
CH (1) | CH606461A5 (en) |
DE (1) | DE2334992C2 (en) |
DK (1) | DK143415C (en) |
FR (1) | FR2192184B1 (en) |
GB (1) | GB1417435A (en) |
NL (1) | NL7309637A (en) |
NO (1) | NO132764C (en) |
SE (1) | SE396093C (en) |
Cited By (33)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4018632A (en) * | 1976-03-12 | 1977-04-19 | Chrysler Corporation | Machinable powder metal parts |
US4096002A (en) * | 1974-09-25 | 1978-06-20 | Riken Piston Ring Industrial Co. Ltd. | High duty ductile cast iron with superplasticity and its heat treatment methods |
US4222793A (en) * | 1979-03-06 | 1980-09-16 | General Motors Corporation | High stress nodular iron gears and method of making same |
US4448610A (en) * | 1982-03-01 | 1984-05-15 | Pont-A-Mousson S.A. | Centrifugally cast tube of spheroidal graphite cast-iron and its method of manufacture |
US4541878A (en) * | 1982-12-02 | 1985-09-17 | Horst Muhlberger | Cast iron with spheroidal graphite and austenitic-bainitic mixed structure |
US4596606A (en) * | 1984-09-04 | 1986-06-24 | Ford Motor Company | Method of making CG iron |
US4619713A (en) * | 1983-02-25 | 1986-10-28 | Hitachi Metals, Ltd. | Method of producing nodular graphite cast iron |
US4737199A (en) * | 1985-12-23 | 1988-04-12 | Ford Motor Company | Machinable ductile or semiductile cast iron and method |
US4880477A (en) * | 1988-06-14 | 1989-11-14 | Textron, Inc. | Process of making an austempered ductile iron article |
EP0374116A1 (en) * | 1988-12-13 | 1990-06-20 | Sandvik Aktiebolag | Roll ring, comprising cemented carbide and cast iron, and method for manufacture of the same |
US4964344A (en) * | 1989-04-28 | 1990-10-23 | Mid-West Conveyor Company, Inc. | Side link pusher dog with lubrication passage |
US4981081A (en) * | 1989-05-24 | 1991-01-01 | Mid-West Conveyor Company, Inc. | Center link pusher dog for power and free conveyors |
US5028281A (en) * | 1988-06-14 | 1991-07-02 | Textron, Inc. | Camshaft |
US5044056A (en) * | 1988-12-13 | 1991-09-03 | Sandvik Ab | Roll ring comprising a ring of cemented carbide metallurgically bonded to a cast iron body |
US5082507A (en) * | 1990-10-26 | 1992-01-21 | Curry Gregory T | Austempered ductile iron gear and method of making it |
US5167067A (en) * | 1988-12-13 | 1992-12-01 | Sandvik Ab | Method of making a roll with a composite roll ring of cemented carbide and cast iron |
US5246510A (en) * | 1992-06-01 | 1993-09-21 | Applied Process | Method for producing a selectively surface hardened cast iron part |
US5248289A (en) * | 1989-12-13 | 1993-09-28 | Sandvik Ab | Cast iron roll with one or more cemented carbide roll rings metallurgically bonded thereto |
US5359772A (en) * | 1989-12-13 | 1994-11-01 | Sandvik Ab | Method for manufacture of a roll ring comprising cemented carbide and cast iron |
US5865385A (en) * | 1997-02-21 | 1999-02-02 | Arnett; Charles R. | Comminuting media comprising martensitic/austenitic steel containing retained work-transformable austenite |
FR2800752A1 (en) * | 1999-11-10 | 2001-05-11 | Mecanique Franc De | PROCESS FOR THE MANUFACTURE OF A CRUDE SPHEROIDAL RAW CAST IRON |
EP1344839A1 (en) * | 2002-01-18 | 2003-09-17 | Ing.Firman Allan Persson HAB | Alloyed nodular cast iron |
US20040013219A1 (en) * | 2002-05-21 | 2004-01-22 | Duke University | Recirculating target and method for producing radionuclide |
US20040074460A1 (en) * | 2002-10-18 | 2004-04-22 | Dhruva Mandal | Valve lifter body |
US20040112173A1 (en) * | 2001-01-24 | 2004-06-17 | Paritosh Maulik | Sintered ferrous material contaning copper |
US20050000314A1 (en) * | 2002-10-18 | 2005-01-06 | Dhruva Mandal | Roller follower body |
US20050063852A1 (en) * | 2001-12-12 | 2005-03-24 | Takeshi Hida | Screw compressor and method of manufacturing rotor for the same |
CN100366758C (en) * | 2004-12-02 | 2008-02-06 | 张志祥 | New technology for nodular cast iron crankshaft isothermal hardening |
US20090104367A1 (en) * | 2005-02-17 | 2009-04-23 | Tritron Gmbh & Co.Kg | Pretreatment and/or precoating of nonabsorbent substrates and/or nonabsorbent support materials |
US20100006189A1 (en) * | 2006-12-16 | 2010-01-14 | Indexator Ab | Austempered ductile iron, method for producing this and component compri |
US20100278293A1 (en) * | 2009-05-01 | 2010-11-04 | Matthew Hughes Stokely | Particle beam target with improved heat transfer and related apparatus and methods |
US20110247581A1 (en) * | 2008-11-19 | 2011-10-13 | Trieschmann Joerg | Gear and balance shaft for a piston engine |
CN111304525A (en) * | 2018-12-11 | 2020-06-19 | 现代自动车株式会社 | Method for manufacturing cam member for continuously variable valve timing system and cam member |
Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI56699C (en) * | 1976-10-05 | 1980-03-10 | Kymin Oy Kymmene Ab | MASKINELEMENT AV SEGJAERN FOER KRAFTOEVERFOERING MEDELST FRIKTION |
FI780026A (en) * | 1978-01-05 | 1979-07-06 | Ovako Oy | KISELLEGERAT STAOL |
DE2853870A1 (en) * | 1978-12-13 | 1980-07-03 | Schmidt Gmbh Karl | BALL GRAPHITE CAST IRON WITH AUSTENITIC-BAINITIC MIXED TEXTURE |
JPS55164055A (en) * | 1979-06-08 | 1980-12-20 | Toyota Motor Corp | Spherical graphite cast iron for surface quenching |
CH653706A5 (en) * | 1981-05-21 | 1986-01-15 | Fischer Ag Georg | METHOD AND DEVICE FOR SECTIONAL HEAT TREATMENT OF COMPONENTS MADE OF FERROUS MATERIALS. |
CH648350A5 (en) * | 1981-12-03 | 1985-03-15 | Fischer Ag Georg | METHOD FOR isothermal austempering OF workpieces made of ferrous materials. |
JPS59129730A (en) * | 1983-01-18 | 1984-07-26 | Toyota Motor Corp | Production of high strength crank shaft |
JPS60121253A (en) * | 1983-12-05 | 1985-06-28 | Nissan Motor Co Ltd | Spheroidal graphite cast iron |
JPS60184659A (en) * | 1984-03-02 | 1985-09-20 | Toyota Motor Corp | Spheroidal graphite cast iron having high strength and toughness |
JPS60197841A (en) * | 1984-03-19 | 1985-10-07 | Nissan Motor Co Ltd | Spheroidal graphite cast iron |
JP2672293B2 (en) * | 1984-08-30 | 1997-11-05 | 日立金属株式会社 | Spheroidal graphite cast iron with excellent mechanical properties |
JPS61136657A (en) * | 1984-12-05 | 1986-06-24 | Ngk Insulators Ltd | Cast metallic mold for molding plastic |
US4666533A (en) * | 1985-09-05 | 1987-05-19 | Ford Motor Company | Hardenable cast iron and the method of making cast iron |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2324322A (en) * | 1940-05-30 | 1943-07-13 | Int Nickel Co | High quality cast iron |
US2485760A (en) * | 1947-03-22 | 1949-10-25 | Int Nickel Co | Cast ferrous alloy |
US3549430A (en) * | 1967-11-14 | 1970-12-22 | Int Nickel Co | Bainitic ductile iron having high strength and toughness |
US3549431A (en) * | 1965-07-27 | 1970-12-22 | Renault | Method of production of cast-iron parts with a high coefficient of thermal expansion |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1121639B (en) * | 1956-03-16 | 1962-01-11 | Renault | Process for the production of cast iron pieces with a maximum thickness of 25 mm and very high toughness |
DE1178451B (en) * | 1957-06-06 | 1964-09-24 | Goetzewerke | Process for the production of non-circular piston rings with high flexural strength and wear resistance |
FR1286077A (en) * | 1961-01-20 | 1962-03-02 | Renault | Steel and treatment to obtain parts with a high thermal expansion coefficient |
-
1973
- 1973-07-06 US US377035A patent/US3860457A/en not_active Expired - Lifetime
- 1973-07-10 NL NL7309637A patent/NL7309637A/xx active Search and Examination
- 1973-07-10 DE DE2334992A patent/DE2334992C2/en not_active Expired
- 1973-07-10 NO NO2828/73A patent/NO132764C/no unknown
- 1973-07-11 CA CA176,179A patent/CA1016372A/en not_active Expired
- 1973-07-11 CH CH1011173A patent/CH606461A5/xx not_active IP Right Cessation
- 1973-07-11 DK DK384473A patent/DK143415C/en not_active IP Right Cessation
- 1973-07-11 FR FR7325396A patent/FR2192184B1/fr not_active Expired
- 1973-07-11 GB GB3303573A patent/GB1417435A/en not_active Expired
- 1973-07-11 JP JP7759373A patent/JPS553422B2/ja not_active Expired
- 1973-07-12 SE SE7309824A patent/SE396093C/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2324322A (en) * | 1940-05-30 | 1943-07-13 | Int Nickel Co | High quality cast iron |
US2485760A (en) * | 1947-03-22 | 1949-10-25 | Int Nickel Co | Cast ferrous alloy |
US3549431A (en) * | 1965-07-27 | 1970-12-22 | Renault | Method of production of cast-iron parts with a high coefficient of thermal expansion |
US3549430A (en) * | 1967-11-14 | 1970-12-22 | Int Nickel Co | Bainitic ductile iron having high strength and toughness |
Cited By (45)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4096002A (en) * | 1974-09-25 | 1978-06-20 | Riken Piston Ring Industrial Co. Ltd. | High duty ductile cast iron with superplasticity and its heat treatment methods |
US4018632A (en) * | 1976-03-12 | 1977-04-19 | Chrysler Corporation | Machinable powder metal parts |
US4222793A (en) * | 1979-03-06 | 1980-09-16 | General Motors Corporation | High stress nodular iron gears and method of making same |
US4448610A (en) * | 1982-03-01 | 1984-05-15 | Pont-A-Mousson S.A. | Centrifugally cast tube of spheroidal graphite cast-iron and its method of manufacture |
US4541878A (en) * | 1982-12-02 | 1985-09-17 | Horst Muhlberger | Cast iron with spheroidal graphite and austenitic-bainitic mixed structure |
US4619713A (en) * | 1983-02-25 | 1986-10-28 | Hitachi Metals, Ltd. | Method of producing nodular graphite cast iron |
US4596606A (en) * | 1984-09-04 | 1986-06-24 | Ford Motor Company | Method of making CG iron |
US4737199A (en) * | 1985-12-23 | 1988-04-12 | Ford Motor Company | Machinable ductile or semiductile cast iron and method |
US4880477A (en) * | 1988-06-14 | 1989-11-14 | Textron, Inc. | Process of making an austempered ductile iron article |
US5028281A (en) * | 1988-06-14 | 1991-07-02 | Textron, Inc. | Camshaft |
AU615125B2 (en) * | 1988-12-13 | 1991-09-19 | Sandvik Ab | Roll ring, comprising cemented carbide and cast iron, and method for manufacture of the same. |
EP0374116A1 (en) * | 1988-12-13 | 1990-06-20 | Sandvik Aktiebolag | Roll ring, comprising cemented carbide and cast iron, and method for manufacture of the same |
US5167067A (en) * | 1988-12-13 | 1992-12-01 | Sandvik Ab | Method of making a roll with a composite roll ring of cemented carbide and cast iron |
US5044056A (en) * | 1988-12-13 | 1991-09-03 | Sandvik Ab | Roll ring comprising a ring of cemented carbide metallurgically bonded to a cast iron body |
US4964344A (en) * | 1989-04-28 | 1990-10-23 | Mid-West Conveyor Company, Inc. | Side link pusher dog with lubrication passage |
US4981081A (en) * | 1989-05-24 | 1991-01-01 | Mid-West Conveyor Company, Inc. | Center link pusher dog for power and free conveyors |
US5248289A (en) * | 1989-12-13 | 1993-09-28 | Sandvik Ab | Cast iron roll with one or more cemented carbide roll rings metallurgically bonded thereto |
US5359772A (en) * | 1989-12-13 | 1994-11-01 | Sandvik Ab | Method for manufacture of a roll ring comprising cemented carbide and cast iron |
US5082507A (en) * | 1990-10-26 | 1992-01-21 | Curry Gregory T | Austempered ductile iron gear and method of making it |
US5246510A (en) * | 1992-06-01 | 1993-09-21 | Applied Process | Method for producing a selectively surface hardened cast iron part |
US5865385A (en) * | 1997-02-21 | 1999-02-02 | Arnett; Charles R. | Comminuting media comprising martensitic/austenitic steel containing retained work-transformable austenite |
US6080247A (en) * | 1997-02-21 | 2000-06-27 | Gs Technologies Operating Company | Comminuting media comprising martensitic/austenitic steel containing retained work-transformable austenite |
FR2800752A1 (en) * | 1999-11-10 | 2001-05-11 | Mecanique Franc De | PROCESS FOR THE MANUFACTURE OF A CRUDE SPHEROIDAL RAW CAST IRON |
EP1099768A1 (en) * | 1999-11-10 | 2001-05-16 | Françoise de Mécanique | Process for the production of as-cast bainitic cast iron with spheroidal graphite |
US20040112173A1 (en) * | 2001-01-24 | 2004-06-17 | Paritosh Maulik | Sintered ferrous material contaning copper |
US20050063852A1 (en) * | 2001-12-12 | 2005-03-24 | Takeshi Hida | Screw compressor and method of manufacturing rotor for the same |
EP1344839A1 (en) * | 2002-01-18 | 2003-09-17 | Ing.Firman Allan Persson HAB | Alloyed nodular cast iron |
US20040013219A1 (en) * | 2002-05-21 | 2004-01-22 | Duke University | Recirculating target and method for producing radionuclide |
US7200198B2 (en) * | 2002-05-21 | 2007-04-03 | Duke University | Recirculating target and method for producing radionuclide |
US20070217561A1 (en) * | 2002-05-21 | 2007-09-20 | Duke University | Recirculating target and method for producing radionuclide |
US20040074460A1 (en) * | 2002-10-18 | 2004-04-22 | Dhruva Mandal | Valve lifter body |
US20050000314A1 (en) * | 2002-10-18 | 2005-01-06 | Dhruva Mandal | Roller follower body |
CN100366758C (en) * | 2004-12-02 | 2008-02-06 | 张志祥 | New technology for nodular cast iron crankshaft isothermal hardening |
US20090104367A1 (en) * | 2005-02-17 | 2009-04-23 | Tritron Gmbh & Co.Kg | Pretreatment and/or precoating of nonabsorbent substrates and/or nonabsorbent support materials |
US7758922B2 (en) | 2005-02-17 | 2010-07-20 | Tritron Gmbh & Co. Kg | Pretreatment and/or precoating of nonabsorbent substrates and/or nonabsorbent support materials |
US20100006189A1 (en) * | 2006-12-16 | 2010-01-14 | Indexator Ab | Austempered ductile iron, method for producing this and component compri |
US20100111662A1 (en) * | 2006-12-16 | 2010-05-06 | Indexator Ab | Method for manufacturing at least part of a device for an earthmoving or materials-handling machine using austempered ductile iron |
US8192561B2 (en) | 2006-12-16 | 2012-06-05 | Indexator Group Ab | Method for manufacturing at least part of a device for an earthmoving or materials-handling machine using austempered ductile iron and its named product |
US20110247581A1 (en) * | 2008-11-19 | 2011-10-13 | Trieschmann Joerg | Gear and balance shaft for a piston engine |
US8561589B2 (en) * | 2008-11-19 | 2013-10-22 | Mitec Automotive Ag | Gear and balance shaft for a piston engine |
US20100278293A1 (en) * | 2009-05-01 | 2010-11-04 | Matthew Hughes Stokely | Particle beam target with improved heat transfer and related apparatus and methods |
US8670513B2 (en) | 2009-05-01 | 2014-03-11 | Bti Targetry, Llc | Particle beam target with improved heat transfer and related apparatus and methods |
CN111304525A (en) * | 2018-12-11 | 2020-06-19 | 现代自动车株式会社 | Method for manufacturing cam member for continuously variable valve timing system and cam member |
US11441204B2 (en) * | 2018-12-11 | 2022-09-13 | Hyundai Motor Company | Method of manufacturing cam piece for continuously variable valve duration and cam piece manufactured therefrom |
CN111304525B (en) * | 2018-12-11 | 2023-08-18 | 现代自动车株式会社 | Method for manufacturing cam member for continuously variable valve timing system and cam member |
Also Published As
Publication number | Publication date |
---|---|
JPS553422B2 (en) | 1980-01-25 |
CA1016372A (en) | 1977-08-30 |
JPS4953115A (en) | 1974-05-23 |
DK143415B (en) | 1981-08-17 |
GB1417435A (en) | 1975-12-10 |
NO132764C (en) | 1975-12-29 |
SE396093B (en) | 1977-09-05 |
FR2192184B1 (en) | 1977-09-09 |
NO132764B (en) | 1975-09-22 |
NL7309637A (en) | 1974-01-15 |
DK143415C (en) | 1981-12-21 |
DE2334992C2 (en) | 1984-08-16 |
FR2192184A1 (en) | 1974-02-08 |
DE2334992A1 (en) | 1974-02-07 |
CH606461A5 (en) | 1978-10-31 |
SE396093C (en) | 1981-03-23 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3860457A (en) | A ductile iron and method of making it | |
CN100503893C (en) | Process for producing gear with hard bainite structure on surface | |
US4415378A (en) | Case hardening method for steel parts | |
CN100532887C (en) | Gear part and method of producing thereof | |
JPH0579742B2 (en) | ||
US4225365A (en) | Lower bainite alloy steel article and method of making same | |
US2087764A (en) | Ferrous alloys and method of manufacture | |
GB2208654A (en) | Method for softening rolled medium carbon machine structural steels | |
US3893873A (en) | Method for manufacturing spheroidal graphite cast iron | |
EP1031631A2 (en) | A method of spheroidizing annealing of hypo-eutectoid low alloy steel | |
US3895972A (en) | Thermal treatment of steel | |
JP2000096185A (en) | Steel for bearing | |
US3826694A (en) | Thermal treatment of steel | |
JPH0238645B2 (en) | KOKYODOKYUJOKOKUENCHUTETSUNOSEIZOHOHO | |
US4853049A (en) | Nitriding grade alloy steel article | |
US3704183A (en) | Method for producing a low-cost hypereutectoid bearing steel | |
JPH04124217A (en) | Production of high strength gear steel excellent in softening property | |
US2585372A (en) | Method of making low-alloy steel | |
US3922181A (en) | Thermal treatment of steel | |
US12104234B2 (en) | Steel material | |
JPS569328A (en) | Forged roll for cold rolling mill | |
JPS62139812A (en) | Manufacture of high strength and toughness cast steel | |
JP3607583B2 (en) | Steel for power transmission parts and power transmission parts | |
CN101586207B (en) | Hot rolling wire rod for mechanical structure of 1600 Mpa level and manufacture method thereof | |
US4396440A (en) | Crushing bodies forged from steel |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCF | Information on status: patent grant |
Free format text: PATENTED FILE - (OLD CASE ADDED FOR FILE TRACKING PURPOSES) |