System and method for manufacturing a cast iron crankshaft with high elasticity and high strength

Abstract

A method (210) for producing a crankshaft (110) made of cast iron with high elasticity and high strength, the method (210) comprising: Providing (212) a sand casting negative mold (30) of the crankshaft (110), the sand casting negative mold (30) having mold cavities to form the crankshaft (110) in a horizontal plane; Providing a feed mechanism (16) arranged adjacent to at least one of the mold cavities of the mold (30), the feed mechanism (16) comprising a feeder (R1-R10) defining a feeder geometry, the feeder (R1-R10) having a port (42) in fluid communication with the feeder (R1-R10) and the at least one of the mold cavities, the port (42) having a neck (44) in fluid communication with the at least one mold cavity, the port (42) having an open end (49) arranged to flare from the neck (44) to the at least one of the mold cavities and to define a connection angle (A1, A2) of the feeder (R1-R10) relative to the horizontal plane; Melting (214) a first metallic material at a predetermined temperature to define a molten metallic material; Feeding (216) the molten metallic material at the connection angle (A1, A2) of the feeder (R1-R10) with the feeder geometry into the mold cavities of the sand casting negative mold (30), wherein the connection angle (A1, A2) of the feeder (R1-R10) corresponds to a connection module of the connection (42), wherein the connection module is at least 10% larger than a casting module (M cf ) of the casting mold (30), wherein the feeder geometry corresponds to a feeder module (M rf ) of the feeder (R1-R10), whereby the feeder module (M rf ) at least 10% larger than the connection module (M nf ) is; Cooling (220) the molten metallic material to a predetermined solidification time in the sand casting negative mold (30) to form a solidified metallic material having the dimensions of the cast iron crankshaft (110); and Separating (222) the solidified metallic material from the sand casting negative mold (30) to define the cast iron crankshaft (110); wherein the first metallic material comprises: 2.2 wt% to 3.2 wt% carbon, C, 1.7 wt% to 2.3 wt% silicon, Si, 0.2 wt% to 0.6 wt% manganese, Mn, up to 0.03 wt% phosphorus, P; up to 0.02 wt% sulfur, S, 0.2 wt% to 0.6 wt% copper, Cu, 0.1 wt% to 0.4 wt% chromium, Cr, 0.4 wt% to 0.8 wt% nickel, Ni, 0.15 wt% to 0.45 wt% molybdenum, Mo, 0.2 wt% to 1.0 wt% cobalt, Co, 0.02 wt% to 0.06 wt% magnesium, Mg, up to 0.002 wt% rhenium Re, 2.5 wt% to 4.0 wt% carbon equivalent and a balance iron, Fe; and wherein the solidified metallic material has a nodule size of 1 micron to 5 microns and a nodule count of more than 200 nodules / mm 2 has.

Description

[0001] This invention was made with government support under U.S. Department of Energy Contract No. DE-EE0008877. The government has certain rights in the invention.

[0002] The present disclosure relates to crankshafts and, more particularly, to systems and methods for manufacturing high resilience, high strength cast iron crankshafts for vehicles.

[0003] A crankshaft is a vehicle part that enables conversion between reciprocating and rotary motion. Crankshafts can be manufactured in numerous ways, including billet, forging, and casting. Currently, the manufacturing of cast iron alloy crankshafts can be improved to achieve greater elasticity, greater strength, greater mass efficiency, and cost savings.

[0004] US 6,415,847 B1 describes a crankshaft casting pattern insert comprising selectively adjustable parts corresponding to the front and rear main journal portions of the crankshaft. Each adjustable section includes a removable insert or element, a key element, a plurality of "vertical" spacers, a plurality of "lateral" spacers, and a fastener element.

[0005] Accordingly, it is the object of the present invention to provide a system and method that enables the production of a crankshaft with higher elasticity and strength.

[0006] The problem is solved by the subject matter of the independent claims.

[0007] While current crankshafts serve their purpose, there is a need for a new and improved system and method for manufacturing vehicle crankshafts, such as cast iron alloy crankshafts. In accordance with the embodiments and examples discussed herein, the present disclosure provides systems and methods for manufacturing a vehicle crankshaft from a cast iron alloy with high elasticity and high strength.

[0008] According to the invention, a method for producing a cast iron crankshaft with high elasticity and high strength is provided. The method comprises providing a sand-cast negative mold for the crankshaft. The sand-cast negative mold has mold cavities for forming the crankshaft in a horizontal plane. The method further comprises providing a feed mechanism disposed adjacent to at least one of the mold cavities. The feed mechanism includes a feeder defining a feeder geometry. The feeder has a port in fluid communication with the feeder and the at least one of the mold cavities. The port has a neck in fluid communication with the at least one mold cavity. The port has an open end configured to flare from the neck to the at least one of the mold cavities and define a connection angle of the feeder relative to the horizontal plane.The method further comprises melting a first metallic material at a predetermined temperature to define a molten metallic material, and feeding the molten metallic material into the mold cavities of the sand casting negative mold at the connection angle of the feeder with the feeder geometry. Furthermore, the connection angle of the feeder corresponds to a connection module of the connection. The connection module is at least 10% larger than a casting module of the casting mold. In addition, the feeder geometry corresponds to a feeder module of the feeder. Furthermore, the feeder module is at least 10% larger than the connection module. The method further comprises cooling the molten metallic material to a predetermined solidification time in the sand casting negative mold to form a solidified metallic material with the dimensions of the cast iron crankshaft.Furthermore, the process includes separating the solidified metallic material from the sand casting negative mold to define the cast iron crankshaft. The first metallic material comprises: 2.2 weight percent (wt%) to 3.2 wt% carbon (C), 1.7 wt% to 2.3 wt% silicon (Si), 0.2 wt% to 0.6 wt% manganese (Mn), and up to 0.03 wt% phosphorus (P); up to 0.02 wt% sulfur (S), 0.2 wt% to 0.6 wt% copper (Cu), 0.1 wt% to 0.4 wt% chromium (Cr), 0.4 wt% to 0.8 wt% nickel (Ni), 0.15 wt% to 0.45 wt% molybdenum (Mo), 0.2 wt% to 1.0 wt% cobalt (Co), 0.02 wt% to 0.06 wt% magnesium (Mg), up to 0.002 wt% rhenium (Re), 2.5 wt% to 4.0 wt% carbon equivalent and a balance iron (Fe). The solidified metallic material has a nodule size of 1 micrometer to 5 micrometers and a nodule count of more than 200 nodules / mm. 2 .

[0009] In another embodiment, the casting module is: Mcf = t cs × C1 × C2 where M cf the feed module of the mold, t cs is the local solidification time at the mold, C1 is a material constant, C2 is a shape constant. In this example, C1 = f( Tliquidus , T mold , T pour , L, k, ρ metal , ρ mold , C pmold , Cp metal ). In this example, T liquidus the temperature of the molten metallic material during the feeding step, T mold is the temperature of the mold, T pour is the temperature of the molten metallic material during the melting step, L is the latent heat of the molten metallic material, k is the thermal conductivity of the molten metallic material, ρ metal is the density of the molten metallic material, ρ mold is the density of the mold, C pmold is the specific heat of the mold and Cp metalis the specific heat of the molten metallic material.

[0010] Based on this design, the connection module is: M nf = t ns × C1 × C2 where M nf the supply module of the connection and t ns the local solidification time at the connection. In addition, the feed module is: M rf = t rs × C1 × C2, where M rf the feed module of the feeder and t rs is the local solidification time at the feeder.

[0011] In another example, the solidified metallic material has a Young's modulus (E) of 175 GPa to 235 GPa. In another example, the solidified metallic material has an ultimate tensile strength (UTS) of 750 to 950 megapascals (MPa) to 1200 MPa, a yield strength (YS) of more than 450 MPa, and an elongation (EL) of more than 3%. In another example, the solidified metallic material has a porosity of less than 10%.

[0012] In one embodiment, the feeding step comprises determining the casting modulus based on a casting geometry at a first location of the mold. The feeding step further comprises determining the connection module to define the connection angle at a second location of the connection. Furthermore, the feeding step comprises determining the feeder module to define the feeder geometry at a third location of the feeder.

[0013] Furthermore, a system according to the invention for producing a cast iron crankshaft for a vehicle is provided. The system comprises a mold unit configured to form a sand-cast negative mold of the cast iron crankshaft in a horizontal plane. The mold comprises at least one mold cavity having a pattern with the dimensions of the cast iron crankshaft. The system further comprises a furnace for melting a first metallic material at a predetermined temperature to form a molten metallic material. The system further comprises a feed mechanism having a feeder defining a feeder geometry. The feeder is arranged to have a port through which the molten metallic material flows. The port has a neck in fluid communication with the at least one mold cavity.The port has an open end that is arranged to widen from the neck toward the at least one mold cavity, thereby defining a connection angle of the feeder relative to the horizontal plane. Furthermore, the feeding mechanism is arranged such that the molten metallic material is fed into the at least one mold cavity at the connection angle of the feeder with the feeder geometry. The connection angle of the feeder corresponds to a connection module of the port. The connection module is 20% larger than a casting module of the mold. The feeder geometry corresponds to a feeder module of the feeder. The feeder module is 20% larger than the connection module.Furthermore, the system includes a cooling area arranged so that the molten metallic material solidifies in the sand casting negative mold at a predetermined solidification time to define a solidified metallic material having the dimensions of the cast iron crankshaft. In addition, the system includes a separating unit configured to separate the solidified metallic material from the sand casting negative mold to define the cast iron crankshaft. The system further includes a controller connected to the mold unit, the furnace, the feeding mechanism, and the separating unit. The controller is configured to control the mold unit, the furnace, the pouring mechanism, and the separating unit. Furthermore, the system includes a power source configured to supply power to the mold unit, the furnace, the feeding mechanism, the separating unit, and the controller.The first metallic material comprises: 2.2 weight percent (wt%) to 3.2 wt% carbon (C), 1.7 wt% to 2.3 wt% silicon (Si), 0.2 wt% to 0.6 wt% manganese (Mn), up to 0.03 wt% phosphorus (P); up to 0.02 wt% sulfur (S), 0.2 wt% to 0.6 wt% copper (Cu), 0.1 wt% to 0.4 wt% chromium (Cr), 0.4 wt% to 0.8 wt% nickel (Ni), 0.15 wt% to 0.45 wt% molybdenum (Mo), 0.2 wt% to 1.0 wt% cobalt (Co), 0.02 wt% to 0.06 wt% magnesium (Mg), up to 0.002 wt% rhenium (Re), 2.5 wt% to 4.0 wt% carbon equivalent and a balance iron (Fe). The solidified metallic material has a nodule size of 1 micrometer to 5 micrometers and a nodule count of more than 200 nodules / mm. 2 .

[0014] In another embodiment, the casting module is: M cf = t cs × C1 × C2 where M cf the feed module of the mold, t csis the local solidification time at the mold, C1 is a material constant, C2 is a shape constant. In this example, C1= f( Tliquidus , T mold , T pour , L, k, ρ metal , ρ mold , C pmold , Cp metal ). In this example, T liquidus the temperature of the molten metallic material during the feeding step, T mold is the temperature of the mold, T pour is the temperature of the molten metallic material during the melting step, L is the latent heat of the molten metallic material, k is the thermal conductivity of the molten metallic material, ρ metal is the density of the molten metallic material, ρ mold is the density of the mold, C pmold is the specific heat of the mold and Cp metal is the specific heat of the molten metallic material.

[0015] In this embodiment, the connection module is as follows: M nf = t ns × C1 × C2, where M nf the supply module of the connection and t ns the local solidification time at the connection. In addition, the feeder module is: M rf = t rs × C1 × C2, where M rf the feed module of the feeder and t rs is the local solidification time at the feeder.

[0016] In another embodiment, the solidified metallic material has a modulus of elasticity (E) of 175 GPa to 235 GPa. In another embodiment, the connection angle of the feeder is between 30° and 75°.

[0017] In another embodiment, the system further comprises a mold element arranged on the casting mold. The mold element is linear and formed in cooperation with the casting mold of the crankshaft.

[0018] According to one application of the present disclosure, a cast iron crankshaft with improved resilience and strength, manufactured by a system and method according to the invention, is provided. The crankshaft includes at least four main bearings aligned on a crankshaft axis defining a centerline. The crankshaft further includes at least three journal bearings. Each journal bearing is arranged about a corresponding journal bearing axis and positioned between the main bearings. Furthermore, each of the respective journal bearing axes is aligned parallel to and radially spaced from the crankshaft axis. Each of the journal bearings is connected to a pair of crank arms to enable power transmission between the journal bearing and the pair of crank arms.Additionally, each pair of crank arms is connected to a corresponding main bearing to transfer torque between the pair of crank arms and the main bearing. Each crank arm has a counterweight positioned opposite a corresponding journal bearing relative to the centerline to ensure balance and stability.

[0019] In this embodiment, each main bearing and each journal bearing comprises a first metallic material with a porosity of less than 15 percent. Furthermore, the first metallic material comprises: 2.2 weight percent (wt%) to 3.2 wt% carbon (C), 1.7 wt% to 2.3 wt% silicon (Si), 0.2 wt% to 0.6 wt% manganese (Mn), up to 0.03 wt% phosphorus (P); up to 0.02 wt% sulfur (S), 0.2 wt% to 0.6 wt% copper (Cu), 0.1 wt% to 0.4 wt% chromium (Cr), 0.4 wt% to 0.8 wt% nickel (Ni), 0.15 wt% to 0.45 wt% molybdenum (Mo), 0.2 wt% to 1.0 wt% cobalt (Co), 0.02 wt% to 0.06 wt% magnesium (Mg), up to 0.002 wt% rhenium (Re), 2.5 wt% to 4.0 wt% carbon equivalent and a balance iron (Fe).

[0020] In one embodiment, the solidified metallic material has a nodule size of 1 micrometer to 5 micrometers and a nodule count of more than 200 nodules / mm 2. In another embodiment, the solidified metallic material has a modulus of elasticity (E) of 175 GPa to 235 GPa. In another embodiment, the solidified metallic material has a tensile strength (UTS) of 750 to 950 megapascals (MPa) to 1200 MPa, a yield strength (YS) of more than 450 MPa, and an elongation (EL) of more than 3%.

[0021] Further areas of applicability will become apparent from the present description. It should be understood that the description and specific examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0022] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Fig. 1 is a schematic view of a system for manufacturing a high-elasticity, high-strength cast iron crankshaft according to an embodiment of the present disclosure. Fig. 2 is a side view of a crankshaft equipped with the system of Fig. 1 was manufactured according to one embodiment. Fig. 3 is a cross-sectional view of the crankshaft of Fig. 2 along lines 3-3. Fig. 4 is a plan view of a feeding mechanism and a mold of the system in Fig. 1 according to one embodiment. Fig. 5A is a side cross-sectional view of a feeder of the feeding mechanism in Fig. 4 along line 5-5. Fig. 5B is a table of the connection angles of the feeders in Fig. 4 according to an example. Fig. 6 is a side cross-sectional view of the feeding mechanism in Fig. 4 along line 6-6. Fig. 7 is an enlarged perspective view of a crankshaft counterweight of the mold in Fig. 4. Fig. 8 is a flow chart of a process for manufacturing a cast iron crankshaft by the system in Fig. 1 according to an example of the present disclosure.

[0023] Fig. 1 shows a system 10 for manufacturing a crankshaft 110 from cast iron ( Fig. 2) with low porosity for a vehicle according to an embodiment of the present disclosure. As shown, the system 10 includes a molding unit 12 configured to receive a sand casting negative mold 30 (see Fig. 9A) of the cast iron alloy crankshaft 110. The sand casting negative mold 30 includes at least one mold cavity, preferably a plurality of mold cavities, to define the crankshaft to be cast. The mold unit 12 is arranged to provide the sand casting negative mold 30 with a pattern having the dimensions of the crankshaft. In one example, the sand casting negative mold 30 has patterns made with green or chemically bonded sand. A core assembly can then be arranged in the mold to further define the dimensions or structure of the pattern. It is understood that the mold can be manufactured in any other suitable manner without departing from the spirit or scope of the present disclosure.

[0024] With reference to the Fig. 2-3, for example, the crankshaft 110 is constructed or arranged to include at least four main bearings 112 aligned on a crankshaft rotational axis 114 that defines a centerline 116 and a horizontal plane H. As illustrated, the centerline 116 is formed by a center point 117 of each main bearing 112, and the horizontal plane H is formed longitudinally along the centerline 116. The horizontal plane H defines an upper half 118 and a lower half 119 of the crankshaft 110.

[0025] The crankshaft 110 is constructed or arranged to include at least three journal bearings 120. As shown, each journal bearing 120 is arranged about a respective journal bearing axis 122 and positioned between the main bearings 112. Furthermore, each journal bearing axis 122 is aligned parallel to and radially spaced from the crankshaft axis 114. Furthermore, each of the journal bearings 120 is connected to a pair of crank arms 124 for transmitting power between the journal bearing 120 and the pair of crank arms 124. Further, each pair of crank arms 124 is connected to a respective main bearing 112 for transmitting torque between the pair of crank arms 124 and the main bearing 112. Furthermore, each of the main bearings 112, the journal bearing 120, and the crank arms 124 is made of a first metallic material.

[0026] As in the Fig. 2 and Fig. 3, at least one of the crank arms 124 is arranged to include a molded counterweight 130. Furthermore, each molded counterweight 130 is positioned opposite a corresponding journal bearing 120 relative to the centerline 116 to ensure balance and stability. During manufacture of the crankshaft 110, the counterweight 130 is molded onto one of the crank arms.

[0027] In one embodiment, the first metallic material comprises iron or an iron alloy. Preferably, the first metallic material comprises a composition comprising 2.2 wt% to 3.2 wt% carbon (C), 1.7 wt% to 2.3 wt% silicon (Si), 0.2 wt% to 0.6 wt% manganese (Mn), up to 0.03 wt% phosphorus (P), up to 0.02 wt% sulfur (S), 0.2 wt% to 0.6 wt% copper (Cu), 0.1 wt% to 0.4 wt% chromium (Cr), 0.4 wt% to 0.8 wt% nickel (Ni), 0.15 wt% to 0.45 wt% molybdenum (Mo), 0.2 wt% to 1.0 wt% cobalt (Co), 0.02 wt% to 0.06 wt% magnesium (Mg), up to 0.002 wt% rhenium (Re), 2.5 wt% to 4.0 wt% carbon equivalent and a remainder Iron (Fe).

[0028] In one example, the first metallic material of the crankshaft has a nodule size of 1 micron to 5 microns and a nodule count of more than 200 nodules / mm 2. In another example, the solidified metallic material has a modulus of elasticity (E) of 175 GPa to 235 GPa. In another example, the solidified metallic material has a tensile strength (UTS) of 750 to 950 megapascals (MPa) to 1200 MPa, a yield strength (YS) of greater than 450 MPa, and an elongation (EL) of greater than 3%. In another example, the solidified metallic material has a porosity of less than 10%.

[0029] Again with reference to Fig. 1, the system 10 further includes a furnace 14 for melting the first metallic material (e.g., iron) at temperatures between 1400 degrees Celsius (°C) and 1600°C to form a molten metallic material. In one embodiment, the furnace 14 may be charged with iron. The furnace 14 may be an arc furnace, an induction furnace, or other suitable furnace without departing from the spirit or scope of the present disclosure.

[0030] As in the Fig. 1 and Fig. 4, the system 10 further includes a feed mechanism 16 arranged to introduce the molten metallic material into the at least one mold cavity of the mold 30 that defines the dimensions of the crankshaft 110 to be cast. In one example, the feed mechanism 16 includes a pouring ladle (not shown), a bottom gate 31, a filter 32 in fluid communication with the bottom gate 31, a runner 34 in fluid communication with the bottom gate 31, and at least one feeder having a feeder geometry in fluid communication with the runner and the at least one mold cavity of the mold. In this example, the feed mechanism 16 includes a plurality of feeders R1-R10, as shown in Fig. 4 shown.

[0031] In this example, the ladle receives molten metallic material (e.g., iron) to pour the molten metallic material into the lower sprue 31, which is provided with a filter 32 to remove oxides from the molten metallic material. As previously mentioned, the lower sprue 31 is in fluid communication with the runner 34 (here a double runner with a first wing 36 and a second wing 38), through which the molten metallic material flows from the filter 32. As shown, the runner 34 is connected to the feeders R1-R10 so that molten metallic material is directed thereto. The runner 34 is arranged to be in fluid communication with the feeders R1-R10, to which the molten metallic material is fed.

[0032] As in the Fig. 4-5A, each feeder, e.g., feeder R3, is arranged to have a port 42 through which the molten metallic material flows. The port 42 has a neck 44 in fluid communication with the at least one mold cavity. As shown in FIGS. Fig. 5A-5B, the neck 44 is arranged to widen or extend from a wall 46 of the port 42 toward the mold 30. Furthermore, the neck 44 extends to an inner base 48, with the inner base 48 arranged to extend, for example, on a slope toward the mold 30. As shown, the neck 44 and the inner base 48 extend to an open end 49 through which molten metallic material can enter the mold 30.

[0033] The neck 44 and the inner base 48, in turn, form a general connection angle of between 30° and 75° relative to the horizontal plane. In one embodiment, the general connection angle is between 31° and 65°. In another embodiment, the general connection angle is between 30° and 55°.

[0034] As in the Fig. 4-5B, the neck 44 defines a first connection angle A1 and the inner base 48 defines a second connection angle A2 relative to the horizontal plane H. As shown in Fig. As can be seen in Figure 5B, each of the feeders R1-R10 has a first and a second connection angle A1, A2, which can vary depending on the dimensions of the crankshaft. For example, the feeder R4 has a first connection angle A1 of 30° and a second connection angle A2 of 1°. This gives the feeder R4 a general connection angle of 31°. The feeder R5, on the other hand, has a first connection angle A1 of 45° and a second connection angle A2 of 10°. This gives the feeder R5 a general connection angle of 55°.

[0035] In this embodiment, each feeder of the feeding mechanism 16 is arranged to feed the molten metallic material into at least one mold cavity, preferably all mold cavities, at a corresponding general connection angle with a corresponding feeder geometry. The general connection angle of each port corresponds to a port modulus of the port. That is, the port modulus defines or dictates the general connection angle at a location on the port such that sufficient molten metallic material can be fed into the mold cavities to compensate for the shrinkage of the first metallic material in the mold during solidification (see below). In this way, the modulus of the port is determined to define the connection angle at a location on the port.As a result, shrinkage and the formation of undesirable defects in the riser occur, which move away from the casting mold.

[0036] In one embodiment, such a terminal modulus may be a numerical length value (e.g., cm) that may be determined experimentally and may depend on the specifications and thermal conditions of the feed mechanism 16, as well as the solidification properties of the first metallic material. Such specifications of the feed mechanism 16 may include, among other things, casting specifications and parameters, terminal specifications, feeder specifications, mold temperature, feeder temperature, terminal temperature, and temperature of the first metallic material.

[0037] The riser geometry of each riser corresponds to a riser module of the riser. This means that the riser module defines or dictates the riser geometry so that sufficient molten metallic material can be fed into the cavities of the mold to compensate for the shrinkage of the initial metallic material during solidification (see below). Thus, the riser module is determined to define the riser geometry at a specific location on the riser. As a result, shrinkage and undesirable voids form in the respective riser away from the mold.

[0038] In one embodiment, such a feeder modulus may be a numerical length value (e.g., cm) that may be determined experimentally and may depend on the specifications and thermal conditions of the feeder mechanism 16, as well as the solidification properties of the first metallic material. Such specifications of the feeder mechanism 16 may include, among other things, casting specifications and parameters, terminal specifications, feeder specifications, mold temperature, feeder temperature, terminal temperature, and temperature of the first metallic material.

[0039] The casting mold has a casting geometry and specifications (including, but not limited to, diameter, length, height, thickness, or material composition) at a location that can be accounted for by a casting modulus. That is, the casting modulus can represent the casting mold at a location that allows for the calculation or determination of variables (e.g., port or riser specifications) for each port and each corresponding riser, so that sufficient molten metallic material can be fed into the mold cavities to accommodate the shrinkage of the initial metallic material during solidification (see below). The casting modulus is therefore determined based on the casting geometry at a location on the casting mold. As a result, shrinkage occurs and unwanted defects form in the riser away from the casting mold.

[0040] In one embodiment, such a casting modulus may be a numerical length value (e.g., cm) that may depend on the specifications and thermal conditions of the feed mechanism 16, as well as the solidification properties of the first metallic material. Such specifications of the feed mechanism 16 may include, among other things, casting specifications and parameters, mold specifications, the temperature of the mold, and the temperature of the first metallic material.

[0041] Preferably, the connecting module is 20% larger than the casting module, and the feeder module is 20% larger than the connecting module to allow sufficient molten metallic material to be fed into the mold cavities of the casting mold 30 and to compensate for the shrinkage of the first metallic material in the casting mold 30 during its solidification (see below). As a result, shrinkage occurs and undesirable voids form in the respective feeder away from the casting mold 30.

[0042] In one embodiment, the casting module is: M cf = t cs × C1 × C2 where M cf the feed module of the mold, t cs is the local solidification time in the mold, C1 is a material constant, and C2 is a shape constant. In this embodiment, C1 can be represented as follows: C1=f(Tliquidus,Tmold,Tpour,L,k,ρmetal,ρmold,Cpmold,Cpmetal) where T liquidusis a temperature of the molten metallic material during the feeding step, T mold is a temperature of the mold, T pour is a temperature of the molten metallic material during the melting step, L is a latent heat of the molten metallic material, k is the thermal conductivity of the molten metallic material, ρ metal is the density of the molten metallic material, ρ mold is the density of the mold, C pmold is the specific heat of the mold and Cp metal is the specific heat of the molten metallic material.

[0043] In an example, the material constant C1 can be represented as follows: C1=ρmetal*L Tliquidus−Tmold×2π×4k×ρmetal×Cpmold+CpmetalTpour−TliquidusL

[0044] In addition, the shape constant C2 can be between about 0.50 and about 0.66.

[0045] Furthermore, in this embodiment, the module of the connection is as follows: M nf = t ns × C1 × C2 where M nf the supply module of the connection and t ns the local solidification time at the connection. In addition, the feeder module is: M rf = t rs × C1 × C2, where M rf the feed module of the feeder and t rs is the local solidification time at the feeder.

[0046] It is understood that the determination of the casting module M cf , of the casting module M cf , of the feeder module is: M rf , the feeder geometry, and the general connection angle can be carried out by experiments together with modules and algorithms of software stored in a central unit of a computer system. Other methods may also be used without affecting the spirit or scope of the present disclosure.

[0047] Fig. 6 shows the feeding mechanism 16 of Fig. 4 for an example of determining the casting modulus M cf , of the connection module M nf and the feeder module M rf As shown, the casting module may represent the casting mold 30 at a location X that allows for the calculation or determination of variables (e.g., port or feeder specifications) at a port C2 and a feeder R2 so that sufficient molten metallic material can be fed into the mold cavities to compensate for the shrinkage of the first metallic material during its solidification. Furthermore, a port module M defines or dictates nfthe general connection angle at a location Y on the connector C2, so that sufficient molten metallic material can be introduced into the mold cavities of the casting mold 30 to compensate for the shrinkage of the first metallic material in the casting mold 30 during its solidification. In addition, the feeder module M defines or dictates rf the riser geometry at a location Z in the riser R2 so that sufficient molten metallic material can be fed into the mold cavities to compensate for the shrinkage of the first metallic material during solidification.

[0048] In this example, the casting module M cf the mold 30 1.363 cm at point X, as in Fig. 6. Therefore, the connection module M nf of the connector C2 at point Y is 1.636 cm, which is 20% larger than the cast module. The feeder module M rfThe feeder R2 is 1.963 at point Z and is thus 20% larger than the connection module. With the connection module M nf the general connection angle at point Y is determined (e.g. 55°). With the feeder module M rf The riser geometry is specified at location Z (e.g., 5 inches in diameter). As a result, shrinkage occurs during solidification of the first metallic material, and undesirable defects form in the riser R2 outside the casting mold 30.

[0049] The sand casting negative mold 30 can then be closed or sealed with chemically bonded sand. The molten metallic material is then allowed to cool to approximately 450°C in a designated cooling area (see below) to solidify the molten metallic material within the mold's plurality of cavities and form a target component with the dimensions of the crankshaft. Preferably, the crankshaft is made of iron with the composition described above.

[0050] In addition, the system 10 includes a cooling area 17 arranged to solidify the molten metallic material. Thus, the cooling area 17 solidifies the molten metallic material with a solidification time of between 5 seconds and 20 seconds in the sand casting negative mold to define a solidified metallic material with the dimensions of the cast iron crankshaft 110. In another embodiment, the solidification time is between 10 seconds and 15 seconds, thereby defining the solidified metallic material. During the solidification of the molten metallic material, the shrinkage of the metallic material is compensated by the shrinkage in the respective risers taking place away from the casting mold 30. This compensation is due to the riser geometry and the general connection angle, which are determined by the riser module M rf or the connection module M nf are defined.

[0051] In order to achieve a desired solidification time range, the cooling region 17 may comprise a cooling element arranged on at least one counterweight of the sand casting negative mold 30. As shown in Fig. 7, a cooling element 50 (in phantom) having a first side 51 is arranged on a counterweight 130 of the mold 30. When molten metallic material is poured into the mold cavities of the mold 30, the cooling element 50 provides a faster cooling effect to solidify the molten metallic material into the solidified metallic material. As shown in Fig. As shown in Figure 7, the counterweight 130 is designed and shaped to linearly complement the first side 51 of the heat sink 50 to improve contact. Furthermore, such a design simplifies the machining of the heat sink 50.

[0052] Back to Fig. 1, the system 10 further includes a separation unit 18 for separating the target crankshaft component from the sand-cast negative mold to define the cast iron crankshaft 110. In one embodiment, the separation unit 18 is arranged to shake or remove the mold containing the chemically bonded sand from the target component. To remove the mold from the target component, an automated unit may be used to break the mold and retrieve the target component therefrom. For example, a vibratory unit or a shaker table with a bottom screen for collecting mold particles from the mold may be used. It is understood that breaking the mold may be accomplished in any other suitable manner without departing from the spirit or scope of the present disclosure.

[0053] In this embodiment, the separation unit 18 is further arranged to devitrify the target component after the mold is removed from the target component. As is known in the art, degassing the target component may involve removing portions of the bonded sand used to fill the mold during casting and gating.

[0054] In one embodiment, the separation unit 18 is further arranged to clean the target component after degassing. In one example, a shot blasting system may be used to apply or shoot beads (e.g., metal beads) onto the surfaces of the target component. To meet alloy design expectations, the separation unit 18 may also include an inspection area where the target component is inspected for its mechanical dimensions, mechanical properties, chemical composition, and microstructure. In one example, a computer-aided system such as a coordinate measuring machine (CMM) may be used to measure the mechanical dimensions of the target component that defines the crankshaft 110.Any suitable methods and equipment may be used to evaluate the dimensions, mechanical properties, chemical composition and structure of the crankshaft without departing from the spirit or scope of the present disclosure.

[0055] Again with reference to Fig. 1, the system 10 further includes at least one controller 20 that communicates with the molding unit 12, the oven 14, the feed mechanism 16, and the separation unit 18. The controller 20 is configured to control the molding unit 12, the oven 14, the feed mechanism 16, and the separation unit 18. In addition, the system 10 includes a power source 22 configured to power the molding unit 12, the oven 14, the feed mechanism 16, the separation unit 18, and the controller 20.

[0056] Fig. 8 shows a method 210 for manufacturing a low porosity cast iron crankshaft for a vehicle according to an example of the present disclosure. In this example, the method 210 may be performed by the system of Fig. 1. As illustrated, the method 210 includes, in box 212, providing a sand casting negative mold for the cast iron crankshaft. As discussed above and in the Fig. 2-3, the crankshaft 110 is constructed or arranged to include at least four main bearings 112 aligned on a crankshaft rotational axis 114 that defines a centerline 116. As shown, the centerline 116 passes through a center point 117 of each main bearing 112, and a horizontal plane H is formed longitudinally along the centerline 116. As shown, the horizontal plane H defines an upper half 118 and a lower half 119. The crankshaft 110 also includes at least three journal bearings 120.

[0057] In this embodiment, each journal bearing 120 is arranged around a corresponding journal bearing axis 122 and positioned between the main bearings 112. Furthermore, each journal axis 122 is aligned parallel to and radially spaced from the crankshaft axis 114. Furthermore, each of the journal bearings 120 is connected to a pair of crank arms 124 for transmitting power between the journal bearing 120 and the pair of crank arms 124. Furthermore, each pair of crank arms 124 is connected to a corresponding main bearing 112 for transmitting torque between the pair of crank arms 124 and the main bearing 112.

[0058] As in the Fig. 2-3, at least one of the crank arms 124 is arranged to include a counterweight 130. Furthermore, each molded counterweight 130 is positioned opposite a corresponding journal bearing 120 relative to the centerline 116 to ensure balance and stability. During manufacture of the crankshaft 110, the counterweight 130 is molded with at least one of the crank arms. Furthermore, the main bearings 112, the journal bearings 120, the counterweights, and the crank arms 124 are made of the first metallic material described above.

[0059] In this example, method 210 further includes melting the first metallic material in box 214 at temperatures between 1400 degrees Celsius (°C) and 1600°C to obtain a molten metallic material. In one example, the first metallic material may be melted by the furnace 14 described above. The furnace may be an arc furnace, an induction furnace, or other suitable furnace without departing from the spirit or scope of the present disclosure.

[0060] The method 210 further includes, in box 216, feeding the molten metallic material into the mold cavities of the sand casting negative mold at a connecting angle with the feeder geometry. The feeding step may be performed by the feeding mechanism 16 described above to feed the molten metallic material into the at least one mold cavity of the mold that defines the dimensions of the crankshaft 110 to be cast. As described above, the feeding mechanism 16 includes a pouring ladle (not shown), a bottom gate 31, a filter 32 in fluid communication with the bottom gate 31, a runner 34 in fluid communication with the filter 32 and the bottom gate 31, and feeders R1-R10 in fluid communication with the runner 34 and the at least one cavity of the mold 30.

[0061] In one example, the connection angle is between 30° and 75°. In another example, the connection angle is between 31° and 65°. In another example, the connection angle is between 30° and 55°.

[0062] In this example, the ladle receives molten metallic material (e.g., iron) to pour the molten metallic material into the lower sprue 31, which is provided with a filter 32 to remove oxides from the molten metallic material. As previously mentioned, the lower sprue 31 is in fluid communication with the runner 34, through which the molten metallic material flows. As shown, the runner 34 is connected to the feeder R1-R10 so that the molten metallic material is directed thereto. The runner 34 is arranged to be in fluid communication with the feeders R1-R10, to which the molten metallic material is fed, at a general connection angle between 30° and 75° in the cavities of the sand casting negative mold. In one example, the connection angle is between 31° and 65°. In another example, the connection angle is between 30° and 55°.

[0063] In this example, each feeder of the feeding mechanism 16 is arranged to feed the molten metallic material into at least one mold cavity, preferably all of the mold cavities, at a corresponding general connection angle with a corresponding feeder geometry. The general connection angle of each port corresponds to a port modulus of the port. That is, the port modulus defines or dictates the general connection angle at a location on the port such that sufficient molten metallic material can be fed into the mold cavities to compensate for the shrinkage of the first metallic material in the mold during solidification (see below). In this way, the modulus of the port is determined to define the connection angle at a location on the port.As a result, shrinkage occurs and undesirable defects form in the riser away from the mold.

[0064] In this example, such a terminal modulus may be a numerical length value (e.g., cm) that can be determined experimentally and may depend on the specifications and thermal conditions of the feed mechanism 16, as well as the solidification properties of the first metallic material. Such specifications of the feed mechanism 16 may include, among other things, casting specifications and parameters, terminal specifications, feeder specifications, mold temperature, feeder temperature, terminal temperature, and temperature of the first metallic material.

[0065] The riser geometry of each riser corresponds to a riser module of the riser. This means that the riser module defines or dictates the riser geometry so that sufficient molten metallic material can be fed into the mold cavities to compensate for the shrinkage of the initial metallic material during solidification (see below). Thus, the riser module is determined to define the riser geometry at a specific location on the riser. As a result, shrinkage occurs and undesirable voids form in the respective riser away from the mold.

[0066] In one example, such a feeder modulus may be a numerical length value (e.g., cm) that may be determined experimentally and may depend on the specifications and thermal conditions of the feeding mechanism 16, as well as the solidification properties of the first metallic material. Such specifications of the feeding mechanism 16 may include, among other things, casting specifications and parameters, terminal specifications, feeder specifications, mold temperature, feeder temperature, terminal temperature, and temperature of the first metallic material.

[0067] The casting mold has a casting geometry and specifications (including, but not limited to, diameter, length, height, thickness, or material composition) at a location that can be accounted for by a casting modulus. This means that the casting modulus can represent the casting mold at a location that allows for the calculation or determination of variables (e.g., port or riser specifications) for each port and each corresponding riser, so that sufficient molten metallic material can be poured into the mold cavities to compensate for the shrinkage of the initial metallic material during solidification (see below). The casting modulus is therefore determined based on the casting geometry at a location within the mold. As a result, shrinkage occurs and unwanted voids form in the riser away from the casting mold.

[0068] In one example, such a casting modulus may be a numerical length value (e.g., cm) that may depend on the specifications and thermal conditions of the feed mechanism 16, as well as the solidification properties of the first metallic material. These specifications of the feed mechanism 16 may include, among other things, casting specifications and parameters, mold specifications, the temperature of the mold, and the temperature of the first metallic material.

[0069] Preferably, the connecting module is 20% larger than the casting module, and the feeder module is 20% larger than the connecting module to allow sufficient molten metallic material to be fed into the cavities of the casting mold 30 and to compensate for the shrinkage of the first metallic material in the casting mold 30 during its solidification (see below). As a result, shrinkage occurs and undesirable defects form in the respective feeder away from the casting mold 30.

[0070] In an example, the casting module is: M cf = t cs × C1 × C2 where M cf the feeding module of the mold, t cs is the local solidification time in the mold, C1 is a material constant, and C2 is a shape constant. In this embodiment, C1 can be represented as follows: C1=f(Tliquidus,Tmold,Tpour,L,k,ρmetal,ρmold,Cpmold,Cpmetal) where T liquidusis a temperature of the molten metallic material during the feeding step, T mold is a temperature of the mold, T pour is a temperature of the molten metallic material during the melting step, L is a latent heat of the molten metallic material, k is the thermal conductivity of the molten metallic material, ρ metal is the density of the molten metallic material, ρ mold is the density of the mold, C pmold is the specific heat of the mold and Cp metal is the specific heat of the molten metallic material.

[0071] In this example, the material constant C1 can be represented as follows: C1=ρmetal*L Tliquidus−Tmold×2π×4k×ρmold×Cpmold+CpmetalTpour−TliquidusL

[0072] In addition, the shape constant C2 can be between about 0.50 and about 0.66.

[0073] In this embodiment, the connection module is as follows: M nf = t ns × C1 × C2 where M nf the supply module of the connection and t ns the local solidification time at the connection. In addition, the feeder module is: M rf = t rs × C1 × C2, where M rf the feed module of the feeder and t rs is the local solidification time at the feeder.

[0074] It is understood that the determination of the casting module M cf , of the casting module M cf , of the feeder module is: M rf , the feeder geometry, and the general connection angle can be carried out by experiments together with modules and algorithms of software stored in a central unit of a computer system. Other methods may also be used without affecting the spirit or scope of the present disclosure.

[0075] As illustrated, the method 210 further comprises, in box 220, cooling or solidifying the molten metallic material with a solidification time of between 5 seconds (sec) and 20 seconds in the sand casting negative mold to define a solidified metallic material having the dimensions of the cast iron crankshaft. The solidification step may be performed by the cooling region 17 described above to solidify the molten metallic material into the solidified metallic material. In another example, the solidification time is between 10 seconds and 15 seconds, thereby defining the solidified metallic material. To achieve a desired solidification time range, the cooling region 17 may include a cooling element disposed on at least one counterweight of the sand casting negative mold. The solidification step may consist of allowing the molten metallic material to cool to approximately 450°C.

[0076] During the solidification of the molten metallic material, the shrinkage of the metallic material is compensated by shrinkage taking place in the respective risers away from the casting mold 30. This compensation is due to the riser geometry and the general connection angle, which are determined by the riser module M rf or the connection module M nf are defined.

[0077] In one example, the first metallic material of the crankshaft has a nodule size of 1 micron to 5 microns and a nodule count of more than 200 nodules / mm 2. In another example, the solidified metallic material has a modulus of elasticity (E) of 175 GPa to 235 GPa. In another example, the solidified metallic material has a tensile strength (UTS) of 750 to 950 megapascals (MPa) to 1200 MPa, a yield strength (YS) of greater than 450 MPa, and an elongation (EL) of greater than 3%. In another example, the solidified metallic material has a porosity of less than 10%.

[0078] The method 210 further includes separating the solidified metallic material from the sand casting negative mold in box 222 to define the cast iron crankshaft. As with the system 10 of Fig. 1, an automated unit is used to remove the mold from the cast crankshaft to break the mold and obtain the cast iron crankshaft therefrom. For example, a vibrating unit or a table with a bottom collecting screen for collecting mold particles from the mold may be used. It is understood that breaking the mold may be accomplished in any suitable manner, such as by a vibrating unit, without departing from the spirit or scope of the present disclosure.

[0079] In this example, the separating step may consist of de-molding the target crankshaft casting after removing the mold from the crankshaft and cleaning the target crankshaft casting after de-molding. As with the system 10 of Fig.1, a shot blasting system may be used to apply or project metal beads onto the surfaces of the target crankshaft casting. To meet design expectations, the separation unit may also include an inspection area where the crankshaft casting to be separated is inspected for its dimensions, mechanical properties, chemical composition, and microstructure. For example, a computer-aided system such as a CMM may be used to measure the mechanical dimensions of the target crankshaft, thereby defining the crankshaft of the present disclosure. Any suitable methods and apparatus may be employed to determine the mechanical dimensions, mechanical properties, chemical composition, and microstructure of the crankshaft without conflicting with the spirit or scope of the present disclosure.

[0080] In one example, the first metallic material is iron or an iron alloy. Preferably, the first metallic material consists of a composition comprising 2.2 wt% to 3.2 wt% carbon (C), 1.7 wt% to 2.3 wt% silicon (Si), 0.2 wt% to 0.6 wt% manganese (Mn), up to 0.03 wt% phosphorus (P), up to 0.02 wt% sulfur (S), 0.2 wt% to 0.6 wt% copper (Cu), 0.1 wt% to 0.4 wt% chromium (Cr), 0.4 wt% to 0.8 wt% nickel (Ni), 0.15 wt% to 0.45 wt% molybdenum (Mo), 0.2 wt% to 1.0 wt% cobalt (Co), 0.02 wt% to 0.06 wt% magnesium (Mg), up to 0.002 wt% rhenium (Re), 2.5 wt% to 4.0 wt% carbon equivalent and a balance iron (Fe).

Claims

[1] A method (210) for producing a crankshaft (110) made of cast iron with high elasticity and high strength, the method (210) comprising: Providing (212) a sand casting negative mold (30) of the crankshaft (110), the sand casting negative mold (30) having mold cavities to form the crankshaft (110) in a horizontal plane; Providing a feed mechanism (16) arranged adjacent to at least one of the mold cavities of the mold (30), the feed mechanism (16) comprising a feeder (R1-R10) defining a feeder geometry, the feeder (R1-R10) having a port (42) in fluid communication with the feeder (R1-R10) and the at least one of the mold cavities, the port (42) having a neck (44) in fluid communication with the at least one mold cavity, the port (42) having an open end (49) arranged to flare from the neck (44) to the at least one of the mold cavities and to define a connection angle (A1, A2) of the feeder (R1-R10) relative to the horizontal plane; Melting (214) a first metallic material at a predetermined temperature to define a molten metallic material; Feeding (216) the molten metallic material at the connection angle (A1, A2) of the feeder (R1-R10) with the feeder geometry into the mold cavities of the sand casting negative mold (30), wherein the connection angle (A1, A2) of the feeder (R1-R10) corresponds to a connection module of the connection (42), wherein the connection module is at least 10% larger than a casting module (M cf ) of the casting mold (30), wherein the feeder geometry corresponds to a feeder module (M rf ) of the feeder (R1-R10), whereby the feeder module (M rf ) at least 10% larger than the connection module (M nf ) is; Cooling (220) the molten metallic material to a predetermined solidification time in the sand casting negative mold (30) to form a solidified metallic material having the dimensions of the cast iron crankshaft (110); and Separating (222) the solidified metallic material from the sand casting negative mold (30) to define the cast iron crankshaft (110); wherein the first metallic material comprises: 2.2 wt% to 3.2 wt% carbon, C, 1.7 wt% to 2.3 wt% silicon, Si, 0.2 wt% to 0.6 wt% manganese, Mn, up to 0.03 wt% phosphorus, P; up to 0.02 wt% sulfur, S, 0.2 wt% to 0.6 wt% copper, Cu, 0.1 wt% to 0.4 wt% chromium, Cr, 0.4 wt% to 0.8 wt% nickel, Ni, 0.15 wt% to 0.45 wt% molybdenum, Mo, 0.2 wt% to 1.0 wt% cobalt, Co, 0.02 wt% to 0.06 wt% magnesium, Mg, up to 0.002 wt% rhenium Re, 2.5 wt% to 4.0 wt% carbon equivalent and a balance iron, Fe; and wherein the solidified metallic material has a nodule size of 1 micron to 5 microns and a nodule count of more than 200 nodules / mm 2 has. [2] The method of claim 1, wherein the casting module is: Mcf=tcs×C1×C2 where M cf the feeder module of the casting mold (30), t cs is the local solidification time at the mold, C1 is a material constant, C2 is a shape constant, and where C1 = f(T liquidus , T mold , T pour , L, k, ρ metal , ρ mold , C pmold , C pmetal ), where T liquidus is a temperature of the molten metallic material during the feeding step, T mold a temperature of the mold (30), T pour is a temperature of the molten metallic material during the melting step, L is a latent heat of the molten metallic material, k is a thermal conductivity of the molten metallic material, ρ metal is a density of the molten metallic material, ρ mold is a density of the mold (30), C pmold is a specific heat of the mold (30), Cp metalis a specific heat of the molten metallic material, where the connection module is: M nf = t ns × C1 × C2 where M nf the feed module of the connection and t ns the local solidification time at the connection is where the feeder module is: M rf = t rs × C1 × C2 where M rf the feed module of the feeder (R1-R10) and t rs is the local solidification time at the feeder (R1-R10). [3] The method of claim 1, wherein the solidified metallic material has a modulus of elasticity (E) of 175 GPa to 235 GPa. [4] The method of claim 1, wherein the solidified metallic material has a tensile strength, UTS, of 750 to 950 megapascals, MPa, to 1200 MPa, a yield strength, YS, of more than 450 MPa and an elongation, EL, of more than 3%. [5] The method of claim 1, wherein the step of supplying comprises: Determining the casting modulus based on a casting geometry at a first location on the casting mold; Determining the connection module to define the connection angle at a second location of the connection; and Determine the feeder module to define the feeder geometry at a third position of the feeder (R1-R10). [6] Method according to claim 1, wherein the connection angle (A1, A2) of the feeder (R1-R10) is between 30° and 75°. [7] The method of claim 1, wherein the solidified metallic material has a porosity of less than 10%. [8] A system (10) for manufacturing a cast iron crankshaft (110) for a vehicle according to a method of claims 1 to 7, the system (10) comprising: a mold unit (12) configured to form a sand-cast negative mold (30) of the cast iron crankshaft (110) on a horizontal plane, the mold (30) comprising at least one mold cavity with a pattern having dimensions of the cast iron crankshaft (110); a furnace (14) configured to melt a first metallic material at a predetermined temperature to form a molten metallic material; a feed mechanism (16) comprising a feeder (R1-R10) defining a feeder geometry, the feeder (R1-R10) being configured to have a port (42) through which the molten metallic material flows, the port (42) having a neck (44) in fluid communication with the at least one mold cavity, the port (42) having an open end (49) arranged to widen from the neck (44) to the at least one mold cavity and to define a joining angle (A1, A2) of the feeder (R1-R10) relative to the horizontal plane, the feed mechanism (16) being configured to guide the molten metallic material into the at least one mold cavity at the joining angle (A1, A2) of the feeder (R1-R10) with the feeder geometry; a cooling region (17) configured to solidify the molten metallic material at a predetermined solidification time in the sand casting negative mold (30) to form a solidified metallic material having the dimensions of the cast iron crankshaft; a separating unit (18) arranged to separate the solidified metallic material from the sand casting negative mold to define the cast iron crankshaft; a controller (20) connected to the molding unit (12), the furnace (14), the feeding mechanism (16), and the separating unit (18), the controller (20) being configured to control the molding unit (12), the furnace (14), the pouring mechanism, and the separating unit (18); and a power source (22) configured to supply power to the molding unit (12), the oven (14), the feed mechanism (16), the separation unit (18) and the controller (20); wherein the first metallic material comprises: 2.2 wt% to 3.2 wt% carbon, C, 1.7 wt% to 2.3 wt% silicon, Si, 0.2 wt% to 0.6 wt% manganese, Mn, up to 0.03 wt% phosphorus, P; up to 0.02 wt% sulfur, S, 0.2 wt% to 0.6 wt% copper, Cu, 0.1 wt% to 0.4 wt% chromium, Cr, 0.4 wt% to 0.8 wt% nickel, Ni, 0.15 wt% to 0.45 wt% molybdenum, Mo, 0.2 wt% to 1.0 wt% cobalt, Co, 0.02 wt% to 0.06 wt% magnesium, Mg, up to 0.002 wt% rhenium Re, 2.5 wt% to 4.0 wt% carbon equivalent and a balance iron, Fe; and wherein the solidified metallic material has a nodule size of 1 micron to 5 microns and a nodule count of more than 200 nodules / mm 2 has.

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