TW469294B - Austempered ductile iron and method for making the same - Google Patents

Abstract

An Austempered ductile iron mainly comprises: 3.5-3.9% of C, 2.4-2.9% of Si, and 0.025-0.04% of Mg. A method for producing such an iron comprises: producing an austenite by raising the temperature of a high temperature furnace to 805-950 degree C; transferring the austenite to a low temperature furnace for Austempering at 280-330 degree C, and maintaining at a constant temperature for 1-3 hours. The Austempered ductile iron according to the present invention can further comprises: 0.001-0.6% of Mn, 0.001-1.0% of Cu, 0.001-1.0% of Ni, or 0.001-0.3% of Mo, in order to improve its hardening energy. The Austempered ductile iron according to the present invention has a better wear resistance, and can be applied on a thick cast article. In a working environment higher than 400 degree C, the matrix texture thereof will not change while maintaining an excellent mechanical property.

Description

469294 V. Description of the invention (1) Field of invention: The present invention relates to a nodular cast iron, in particular to a Voss tempered nodular cast iron and its manufacturing method. It has better wear resistance and can be applied to thick castings. At 400 ° C, Al Qaeda does not mutate, but still maintains excellent mechanical properties. Previous technology: Iron and steel (Cas t I ron) material is mainly composed of two basic elements of iron and carbon, in which the carbon content is less than 0.02% is called pure iron, between 0.02 ~ 2. 14% This is carbon steel, and those above 2.14% are generally called iron. Cast iron is the molten iron village, pouring bells into the mold. It is called solid cast iron. It is called cast iron β. The main chemical composition of cast iron, in addition to iron, contains carbon 'silicon, manganese, phosphorus, sulfur and other five major elements'. Sometimes other alloy elements are added to improve the microstructure. (Microstructure), Heat Treatment (Heat Treatment) characteristics-and Mechanical Properties (Mechanical Property). Because cast iron has a wide range of mechanical properties and is inexpensive, it is currently the most widely used reading material. Cast iron can be divided into white cast iron (ffhi te Iron), spotted iron (Mottled Iron), gray iron (Gray Iron), shrink graphite cast iron canopy. (C ompacted Grajjhite Cast Iron), Ductile iron (D u ς ti 1 e Cast Iron), Vos tempered ductile iron (Austempered Dueti 1 e I ron, AD I) and malleable cast iron (Ma 1 1 eab 1 e I ron) and other 7 categories. Ductile iron is stronger than gray cast iron and has ductility, so it has been developed since 1984. So far, the annual output of nodular cast iron in industrial countries has reached 20 ~ 50. 0% of the total cast iron output, which has grown extremely rapidly. As shown in Figure 1, nodular cast iron is composed of spheroidal graphite and ferrous phase bases. “Iron phases generally under bound forming energy” P00-044.ptd Page 4 469294 5. Description of the invention (2) Mainly fat. Miscellaneous iron and wave .. Iron. Nodular scales. Iron stone. 'The shape of the ink is spherical. Because the properties of nodular cast iron are related to the roundness of graphite and the number of nodular inks, nodularity and nodular numbers are often performed during the metallographic examination of cast iron. Detection, '. The spheroidization ratio and the number of spheroids can be measured by comparing the uncorrupted silver multiple metallographic phase with the standard metal phase to determine the result 'or using an image analyzer to determine the result. The mechanical properties of ductile iron are mainly related to the base. As with the gray cast iron, in the casting state, its base organization is fertile iron and bolai iron. This is also an important inspection item.

Voss tempered ball iron (Austempered Ducti 1 e I r ο η, hereinafter referred to as AD I) is a ballless tempered iron processed by Voss tempering (115115111? 61 ^ 1 ^). Its base level knowledge is mainly It is composed of Ba initic Ferrite and residual

(R stained Austeni 1: e-series, fat-grained iron-series nodular cast iron, while maintaining considerable ductility and excellent wear resistance, in many applications its properties are similar to cast steel, .. Forged steel is even better, so in recent years, ADI has been regarded by the cast iron industry as the most promising iron material. However, the aforementioned Xi De Hans, Fire Ball Ink Iron (ADI) Because of its improper alloy design and unsuitable heat treatment conditions, = Ϊ ΐ f ί Vos tempered ductile chain iron, that is, the existence of waves in its alpine organization, in addition to poor mechanical properties 'except' even more difficult to obtain good resistance Abrasive.

Or, at working places higher than 400 ° C, we can get r a η τ, * drink, the current base-level weaving of tempered ductile iron (ADI) often mutates and affects its mechanical properties. As a result, the current Worworth Tempered Ductile Iron (ADI) will be modified

469294 Five 'invention description (3) Good, when used in thick castings, "it still has good mechanical properties and abrasion resistance, and in workplaces higher than 400 nC, its base organization will not mutate, and It still maintains excellent mechanical properties. Summary of the invention: The main purpose of the present invention is to provide a Voss tempered ductile iron, which is used in thick inlaying, it has: good, good, good: mechanical, properties: and .. resistant :, frightening The secondary purpose of the present invention is to provide a Voss tempered ductile cast iron whose alpine organization will not mutate in a working place higher than 400 t, while still maintaining excellent mechanical properties. In order to achieve the above purpose, the present invention: Vos tempered nodular cast iron, which mainly contains 3.5-3.9? 1 carbon, 2, 4 ~ 2.9% chopped, and 0,025 "0,04% magnesium, raised in a high temperature furnace To 8 5 0-9 5 0 t for iron field ironing treatment for 1-4 hours, and then sent to low temperature pass for Vos tempering, tempering temperature 2 8 0-3 3 0 ° C, constant temperature for 3 hours, so that Its tendency is HRC 3 8-47. The Vos tempered ductile iron of the present invention may further contain 0 _ 0 0 1-0.6% manganese, 0.0 0 1-1 · 0% copper, 0. 0 01-1. O ft nickel or 0.001-0. 3% molybdenum to improve its hardening energy., ^^ — 篆 According to a preferred embodiment of the present invention, Voss tempered ductile iron coated valley 3.6% carbon, 2. 6 % Silicon, (K 0.3% magnesium, 0.3% nickel, 0.6% copper, 0.4% manganese or 0.2% molybdenum. This composition can constitute a better ADI organization And mechanical properties. The Root-Tempered Ductile Iron of the present invention and its manufacturing method have better abrasion resistance, can be applied to thick castings, and are used in workplaces above 400 ° C. Al Qaeda does not Will mutate while still maintaining excellent mechanical properties. The Voss tempered ductile iron of the present invention can be used to replace spheroidal graphite cast iron, tools

p〇〇.〇44, ptd page 6 469294 V. Description of the invention (4) Steel and alloy steel may be used instead of rolled steel. In order to make the above and other objects, features, and advantages of the present invention more clearly disclosed and understood, the preferred embodiments of the present invention are hereinafter described in detail with reference to the accompanying drawings. Description of the invention: The so-called Voss tempered ductile iron AD I is the process of tempering the ductile cast iron by Voss tempering, so that the base becomes a composite structure of toughened fat iron and residual Vostian iron, which is stronger than traditional ductile iron. Cast iron with considerable ductility and excellent wear resistance. In many heavy-duty wear-resistant applications, it can partially replace cast indium and forged steel,

In the process of AD I, there are many variables that will affect the metamorphosis of Voss fertilized iron (variable fertilized iron + residual Vostian iron) and change the properties and organization of AD I. The main variables such as basic chemical composition, The application of alloys, heat treatment parameters and ':: section_section size', etc., and the addition of alloys, the impact must be paid special attention. Because the addition of alloy can improve the hardening energy, and its addition amount should not be adversely affected by ADI in the process of toughening iron metamorphosis. Generally, the alloy not only affects the heat treatment reaction but also affects its mechanical properties. ADI has sufficient hardening energy. If too much alloy is added, a longer Voss tempering time is required.

In order to obtain AD I castings with excellent mechanical properties, good quality ductile iron castings must be completed first, and then a complete Voss tempering heat treatment can be performed to obtain high strength and appropriately ductile castings. If nodular cast iron has defects, improper selection of heat treatment parameters, or poor control during heat treatment, satisfactory products will not be obtained. Such as nodular cast iron with poor nodularity, low nodular number and other casts

P00-044.ptd Page 7 469294 V. Description of the invention (5) The existence of the shelter will be a considerable hazard to ADI castings. In the process of Vos tempering, the addition of alloys, the selection of Vos tempering temperature and time, and the control of cooling rate are also important for obtaining ADI castings with excellent mechanical properties. In the thick casting ADI, in order to overcome the mass effect, some alloying elements are often added to the ductile iron ten to prevent the occurrence of wave iron in the base during the Vos tempering process, although the addition of alloys can often improve or enhance certain machinery. Nature, but accidental addition can easily lead to serious segregation phenomenon * The occurrence of this phenomenon caused difficulties in Voss tempering, that is, the imbalance of the deformed iron grains, so the base _ often has a deer phase Appears, and seriously affects the mechanical properties of ADI. Vos tempered ductile iron according to the present invention, which mainly contains 3.5-3.9% carbon, 2, 4-2. 9% silicon and 0 2 5-0, 04% magnesium. The high temperature furnace is heated to 8 50-9 50 ° C for Vossian ironing, and then sent to the low temperature furnace for Vos tempering. The tempering temperature is 2 8 0 -3 30 ° C, and the temperature is maintained for 3 hours to make it Hardness HRC38-47. The Vos tempered ductile cast iron of the present invention may further contain 0.6% manganese, 0.001-1.0% copper, 0.0CH-1.0% nickel or O.OtH-0.3 # molybdenum to improve its hardening performance. The diffusion of carbon is proportional to temperature, and if the number of nodular cast iron increases, the distance of interdiffusion decreases, which also helps the diffusion to complete. However, the carbon content of Vostian iron is closely related to the silicon content. Sex. According to the invention, Vos tempered ductile cast iron, which mainly contains 3. 5-9. 9% carbon and 2. H 9% silicon, preferably, 3.6% carbon and 2.6% of Silicon, this composition can constitute better ADI organization and mechanical properties.

P00-044.ptd Page 8 46 929 4 V. Description of the Invention (6) Nickel is the most commonly used element in AD, mainly because it has a better impact on al-Qaida than other elements. * It is easy to add and will not. There are the formation of eutectic carbides and the eluates between eutectic cells, but in the high-recording ADI (N i> 2㈣), due to the result of segregation, there will be different in different Vostian iron cells. Toughening fertilizing iron metamorphosis rate. Copper is the same as other alloying elements, and its main purpose is to improve the Voss tempering ability (Austemper abi 1 i ty) so that the ADI process can affect its microstructure and mechanical properties. Copper and molybdenum Adding together to improve the Voss tempering ability, its effect is more effective than individual additions. Because copper can slow down the second stage metamorphosis of toughened iron and iron, so the range of Voss tempering can be increased, within this range It can maintain the ductility and balance strength of castings. The application of molybdenum in ADI is very common. The main purpose of adding molybdenum is to improve the Voss tempering ability. In this regard, the efficacy of molybdenum is the strongest. It has been reported that- Out of the Moss tempering ability of AD I, The effect of segregation and mechanical properties is similar to that of manganese. However, the difference from manganese is that molybdenum can stabilize fertilizer particles instead of vostian iron, and through experimental observations-molybdenum can slow down the toughening fertilizers in the first stage and the first stage. Deformation of granular iron. The effect of molybdenum on the tempering capacity of Voss is about 10 times that of ^. Many literatures indicate that the percentage of molybdenum when adding molybdenum depends on the thickness of the section and the required hardening energy. Segregation tends to form brittle regions at the boundary of eutectic cells, which should be paid special attention. As mentioned above, molybdenum is a strong promoter of Voss tempering ability and also easily promotes the formation of carbides. It is best not to exceed two. 0.3%. Manganese can stabilize Vosstian iron, is not expensive, and Voss tempering ability is second only to molybdenum, but its segregation is easy to form unaltered Vosstian iron at the eutectic cell boundary in ADI.

P00-044.ptd Page 9 469294 V. Description of the invention (Ό (Unreacted Expensive ability to adversely affect the energy, the segregation effect when adding _ mechanical properties. According to the hair. 0% nickel, 0, the key ° Better copper »0.4¾ Microstructure and mechanical casting: plus make the base completely ring last time length " average temperature is related to time. Vostian iron dolphins high carbon content balance increase, until, dissolve iron Chemical means base content. Voss state reaction temperature

Aus ten i te) while remaining in AD I, will affect the mechanical properties, so the manganese content is generally about 0.3%. Nickel and steel promote the lower hard molybdenum and molybdenum, but they are also widely used. However, the price of nickel is mainly based on the minimum amount. To reduce the addition of alloys, the number of ball inks can be increased to reduce the segregation effect and improve its maintenance. For a period of t, the heating temperature is 1¾ low, and the appropriate and alloy is mainly the shadow time 'Vos. Hold ... temperature time ends, so and Vostina' perverted, then Vost 'back till Ming Vost tempered ductile iron 001 -1, 0% copper »0.001- 'Voss tempered ductile iron may be fine or 0.2%. ; This > nature. Heat to Vosstian Ironing Temperature ‘degree and Vosstian Ironing. In this step, mechanical properties, but Vostian ironization will affect the final mechanical properties and casting size, chemical composition temperature and holding temperature time, Vostian ironization temperature is higher. The measurement speed reaches the saturated carbon content, and the ground is completely metamorphosed to Vostian. The faster the heating speed of Tietian Ironization will increase. According to this post 0

, Which may additionally include 0.00 1-1. 0.6% manganese or 0.001-0. 3% and 0-3% nickel, 0.6% of the composition can constitute " better AD I for a proper time, the rate will not The degree of crystallization of Vostian iron that is related to Vostian ironization is related to the growth of Vostian iron molten iron, and the so-called Vostian iron must reach fuller carbon as soon as possible and become nodular cast iron.

P00-044.ptd Page U) 469294 V. Description of the invention (8) '· ADI' Vostian ironization temperature is preferably 85 ~ 95. 〇, constant temperature Bu 4 hours. Special attention should be paid to the process of quenching the ytian ironized castings to the Voss tempering constant temperature tank. The dead time is as far as possible: as short as possible to prevent cooling. If the speed is too slow, it will generate wave iron and make the machine Degraded. The required cooling rate is related to the size of the casting and the Voss tempering capacity. The larger the size or the smaller the hardening energy, the greater the quenching degree is required. Therefore, the Voss tempering ability is poor or too poor. All alloy elements must be added to increase the Voss tempering ability of the casting. In addition, the casting must reach the Voss tempering temperature before the Voss tempering reaction begins.

The tempering process is to quench the ironed casting of Vostian to a low temperature constant = tank and take it out for a suitable period of time, and then air or forced cooling to the room ^ ° The medium used in the low temperature constant temperature tank can be It is an oil bath, a salt bath (, alt Bgth) or a fluidized bed of fine sand (Fluidized Bed). Among them, the salt is a mixture of KN03, NaN03 and NaN〇2 as the heating medium, and the point is that the temperature within the salt is uniform and stable ', but it must have a good stirrer to make Γ to 7 ^ The heat absorbed by the chemical casting can be quickly. = The casting after the salt bath treatment must be completed and dried on the surface of the casting to prevent the casting from being corroded by the residual salt. two

The range of the tempering temperature of each Voss is approximately 25 (rC (above Ms point) to 45 ° and above the second tender point to WO C. When Voss tempering is performed, the needle Ϊ Ϊ fertilizer iron grows rapidly, and The diffusion rate of the broken element is relatively low. In the future, the carbon content of the Feitian money is increased due to the precipitation of ferrous iron. At the beginning of the rapid cooling, the part of the carbon element discharged by the ferrous iron described in the peach t is in the needle. Fertilizer-like iron emerges as fine e-carbide. Vos is formed due to the formation of e-carbide

46 92 9 4 V. Description of the invention (9) Tian Tie's carbon content decreased and became indefinite. After the heat treatment was completed: this: Voss Tian Tie was maintained and the remaining part was small. The above-mentioned structure is generally referred to as the down-toughened ferritic iron structure. Its group has fine texture, high strength and hardness, but poor ductility. * It is suitable for occasions with higher contact stress. U is at a higher temperature (3 3 0 ~ 4 5 0 ° C) When Voss tempered, its metallographic structure is slightly different from the former, so the diffusion of carbon and elements is faster, so most of the carbon elements can be toughened by plate-like iron. It is discharged inside and enters the adjacent Vosstian Iron, so that its carbon content increases and the squeeze becomes a residual Vosstian Iron organization. At this time, if the Vos tempering process is no longer maintained at its constant temperature state, when it is cooled to Ms, the line will change: change; to Asada loose iron, if: continue to maintain the constant temperature state, its carbon content The performance will be increased to about 1. 5 ~ 1. 7%, and it will no longer be transformed into toughened iron. In addition, due to the increase in carbon content, the Ms line is also suppressed, and its residual Vosstian iron no longer changes during cooling to room temperature. The residual Vosstian iron structure is extremely stable, even reaching -1 2 0 ° C remains unchanged. Its structure is relatively coarse, its strength and hardness are low, but its ductility is better, and it is more suitable for high impact load or high cycle fatigue. During the tempering of Voss, if the temperature holding time is too short, loose iron can be formed in the ferrous grain iron tissue of Voss, because the Vos tempering time is insufficient, and the carbon content is low in many Vosstian iron regions. At this time, if the temperature is stopped and the temperature is cooled to room temperature, the Vostian iron will be transformed into Asada scattered iron to form a brittle region. If you increase the tempering time of Gavos, the carbon will continue to diffuse, especially in the warmer tempering Voss temperers, most of the carbon in the changed fertile iron can be discharged to make Voss As Tiantie ’s carbon content increases, as soon as the termination of the Voss tempering, Asada loose iron will

F00-044, ptd Page 12, 4,69294 V. Description of invention (ίο) Significantly reduced. According to the invention, the Wors tempered ductile iron AD; I, the tempering temperature is preferably 2 8 0-3 3 0 t: constant temperature for 1-3 hours, so that its hardness reaches HRC38-47. The Vos tempered ductile iron and its manufacturing method according to the present invention have better abrasion resistance, can be applied to thick castings, and in working places higher than 400 ° C, the Al Qaeda will not mutate, but still maintain excellent Mechanical properties. The Vos tempered ductile iron of the present invention can be used to replace the nodular graphite cast iron and used in the track block and camshaft of the track car; or it can be used to replace the tool steel and alloy steel and used in the cement pump truck brake plate or grinding mill Ball; or instead of rolled steel, used in gear: sister, or steel Ί1: .. Although the present invention has been disclosed in the foregoing preferred embodiments. However, it is not intended to limit the present invention, and anyone familiar with this technology Various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application. Korea

P00-044.ptd Page 13 469294 Brief description of the drawings Explanation of the figure: Figure 1: Metallographic structure of ductile cast iron; and Figure 2: Metallographic structure of Vos tempered ductile cast iron according to the present invention. II ··! P00-04 Winter ptd Page 14

Claims (1)

469294 VI, 2 4 6 78 Scope of patent application, a Voss tempered ductile iron, which contains: 3, 5-3. 9% carbon "2, 4-2. 9% silicon and 0.025-0. 04% magnesium, heated to 850 0-950 ° C in a high-temperature furnace for Voss Φ ironization treatment for 1-4 hours, and then sent to a low-temperature furnace for tempering at Voss, tempering temperature 2 8 0-3 3 0 ° C, constant temperature 1-3 hours. 6% 的 Mn。 According to Vos tempered nodular cast iron according to item 1 of the scope of patent application, it additionally contains 0.00 0. 0. 6% of manganese. 2. According to Voss tempered nodular cast iron according to item 1 of the scope of patent application, it also contains 0.001-1.0% copper. According to item 1 of the scope of patent application, Vos tempered ductile iron, which additionally contains 0, 0 01-1, 0% brocade. 3, according to the scope of patent application No. 1 Vos tempered ductile iron, which additionally contains 0.00 1-0. 3% of molybdenum. 2. Vos tempered ductile cast iron according to item 1 of the scope of patent application, wherein the Vos tempered ductile cast iron contains 3.6% carbon, 2.6% broken and 0.03% magnesium U 1ST, according to Vos returned to Ul graphite cast iron in the second scope of the patent application, in which the manganese is 0.4%. 6%。 Vos tempered ductile iron according to item 3 of the scope of patent application, where the copper is 0.6%. 3%。 In accordance with the scope of the patent application No. 4 Yi Nongbei nodular cast iron 'where the nickel is 0.3%. 0. According to the 5th scope of the patent application, Worth $ Fire Ductile Iron, where the steel is 0.2%. P00-044.ptd 笫 page 15 6 9 2 9 4 Scope of patent application A method for manufacturing Voss tempered ductile iron, which includes the following steps: forming a silicon and 0. at high overflow: and at low temperature for hours. , Method of claim, method of claim, method of claim 1 5. method of claim 1 6, method of claim 6% of silicon 1 7. method of claim, _ 1 8, method of claim, 1 9. Eschen ductile iron, which contains 3.5-3 · 9% carbon, 2 4-2. 9% 0 2 5-0 · 04% magnesium; the furnace is heated to 8 5 0-9 5 0 ° C. Vostian ironing treatment 1-4 small furnaces for Voss tempering, tempering temperature 2 8 0-3 3 0 t, constant temperature 3 3 4 Please apply for the system of patent scope item 11; _ its :. Otn-i. 〇%, including 0 :, &, .0 :: 1: .__ 0 ... :: 6:% The patent system of item 11 of the patent application, which also includes 0.00. Ooi-i ^ o% of the patent system of item 11, which also includes 0.001-0. 3% of the patent application park The system of item 11, wherein the Voss tempering ball is cast in daytime and 0.03% of magnesium. 4%。 Please manufacture in the scope of patent No. 12 wherein the 銾 is 0.4%. 6%。 Please cover the scope of the patent No. 13 Among them talk about steel: 0.6%. Please make the manufacture of Vos tempered ball ingots. . Beavers Back "Fireball Ink Copper. Made $ 斯 回 火球 墨 墨 链 Chain 'made Vos tempered ball ink cast Gu. Feng Vos tempered ball cast iron contains 3.6% carbon, Vos tempered ball cast Vos tempered ball cast iron iron iron iron iron hoof cast iron cast iron • · Ί Vos tempered ball. P00-044.ptd Page 16 4.6 92 9 4 VI. Patent Application Method, where the nickel is 0.3% '. 20. The method for manufacturing Voss tempered ductile iron according to item 15 of the scope of the patent application, wherein the pin is 0. _ P00-044.ptd Page 17