Abstract: A multi-gap type rotary electric machine is provided, where the machine is provided a shaft supported rotatably by a baring secured to a housing. An annular rotor is secured to the shaft and configured to rotate together with the shaft. Double stators are secured to the housing and configured to have gaps between the stators and the rotor. Relationships of: 3.5<P13/P6??(1) and P7/P6>1??(2) are met, where P6 denotes a circumferential width of each of outer salient poles, P7 denotes a circumferential width of each of inner salient poles, and P13 denotes a circumferential width of each of the outer magnets.

Abstract: System and method of producing multi-layered aluminum alloy products are disclosed. A multi-layered aluminum alloy product may be formed by first heating a first aluminum alloy to a first temperature where the first temperature is at least about 5° C. lower than the eutectic temperature of the first aluminum alloy, second heating a second aluminum alloy to a second temperature where the second temperature is at least about 5° C. higher than the liquidus temperature of the second aluminum alloy, and coupling the second aluminum alloy to the first aluminum alloy to produce a multi-layered aluminum alloy product.

Abstract: Molten metal of a first composition is fed into a mold cavity, via a first control apparatus, wherein the control apparatus is open, wherein the feeding includes at least flowing out of a first feed chamber. The first control apparatus is closed. A second control apparatus is opened. Molten metal of a second composition is fed into the mold cavity, via the second control apparatus, wherein at least a portion of the metal of the first composition in the mold cavity is sufficiently molten so that an initial feed of molten metal of the second composition mixes with the molten metal of the first composition in the mold cavity, wherein the feeding includes at least flowing out of a second feed chamber, wherein the second composition is different from the first composition.

Abstract: A method for manufacturing a bi-material sleeve is provided. The sleeve includes an annular outer sleeve and an annular inner sleeve bonded to each other. The bottom pouring of the outer sleeve is carried out in a casting space delimited by a wall of a first ingot mold and by an outer upwardly moveable wall of a second ingot mold concentric with the first. The moveable wall of the second ingot mold is raised so as to uncover the skin of the outer sleeve which has solidified thereagainst. The bottom pouring and the solidification of the inner sleeve are carried out in a casting space delimited by said skin and an inner stationary wall of said second ingot mold, the bonding of both sleeves being effected by diffusion between said sleeves. Forging and/or machining of one of said bonded sleeves are optionally carried out. A device for using this method and a sleeve produced by this method are also provided.

Abstract: The present invention provides a method for manufacturing a composite double-metal fracture splitting connecting rod, comprising the steps of: providing a moveable spacer at a large end of a mold cavity of a connecting rod, to divide the mold cavity into two separate parts; casting a connecting rod body and a connecting rod cap with material for the main body of the connecting rod; removing the spacer from the mold cavity when the majority of the material is solidified, then injecting material for a fracture splitting region into an empty mold cavity obtained after the removal of the spacer, and metallurgically bonding the two types of material to form a composite double-metal casting; then, separating the connecting rod body from the connecting rod cap by a fracture splitting apparatus along preset fracture surfaces; and positioning and accurately assembling through engaged staggered structures on the two fracture surfaces.

Abstract: A centrifugally cast composite roll comprising an outer layer formed by a centrifugal casting method, and an inner layer made of ductile cast iron and integrally fused to the outer layer; the outer layer being made of an Fe-based alloy having a chemical composition comprising by mass at least 0.8-3.0% of Cr, 1.5-6.0% of Mo, and 1.8-5.5% of V, and a metal structure in which the area ratio of graphite is 0.3-10%; the inner layer comprising a roll body portion fused to the outer layer, and shaft portions integrally extending from both ends of the roll body portion; and the total amount of Cr, Mo and V being 0.15-2.0% by mass in end portions of both shaft portions, and the difference in the total amount of Cr, Mo and V between one shaft portion and the other shaft portion being 0.2% or more by mass.

Abstract: A method is provided for casting an article such as a blade having an attachment root and an airfoil, the airfoil having a proximal end and a distal end. The method comprises introducing a molten alloy into a mold; and varying a composition of the introduced alloy during the introduction so as to produce a compositional variation.

Abstract: A method of casting an article includes positioning a first portion of the article, formed from a first material, in a rotatable mold. Additionally, the method includes, while rotating the mold, pouring a molten second material into the mold over the first portion to form a second portion of the article that is metallurgically bonded to the first portion of the article.

Abstract: Molten metal of a first composition is fed into a mold cavity, via a first control apparatus, wherein the control apparatus is open, wherein the feeding comprises flowing out of a first feed chamber. The first control apparatus is closed. A second control apparatus is opened. Molten metal of a second composition is fed into the mold cavity, via the second control apparatus, wherein at least a portion of the metal of the first composition in the mold cavity is sufficiently molten so that an initial feed of molten metal of the second composition mixes with the molten metal of the first composition in the mold cavity, wherein the feeding comprises flowing out of a second feed chamber, wherein the second composition is different from the first composition.

Abstract: Technology of production of bimetallic and multilayer casts by gravity or spun casting, at which at least two different metal materials are being gradually cast into the mold, while before casting of the second material there is started feeding of a flame into the mold and the flame is created by stream of aflame inflammable gas. Stream of aflame inflammable gas is created by hydrogen flame.

Abstract: A method of forming a casting includes providing a preform to a mold cavity. The preform is formed from one of a first metal and a second metal and defines an interface surface. A molten portion of the other of the first metal and the second metal is cast into the mold such that the molten portion proximately contacts the interface surface of the preform. An interface layer at the interface surface, a first portion defined by the mold cavity and the interface layer, and a second portion defined by the interface layer, are formed during casting. The interface layer may define a metallurgical bond between the first portion and the second portion. In the non-limiting example provided herein, the first portion is substantially comprised of aluminum and the second portion is substantially comprised of magnesium. In a non-limiting example, the casting may be configured as a vehicle wheel.

Abstract: Provided is a porous metal body containing at least nickel, tin, and chromium. An example of a method of producing such a porous metal body is a method including a conductive-coating-layer formation step of forming a conductive coating layer containing chromium on a surface of a porous base formed of a resin material; a metal-layer formation step of forming a nickel layer and a tin layer in any order on a surface of the conductive coating layer; a removal step of removing the porous base; and a diffusion step of, by a heat treatment, causing interdiffusion of metal atoms between the nickel layer and the tin layer and diffusing chromium contained in the conductive coating layer into the nickel layer and the tin layer.

Abstract: A cylinder head is formed by positioning a clad preform including a first and second layer in a casting die cavity with the second layer in communication with the die cavity and the first layer facing outwardly to define a combustion surface. Molten material provided to the die cavity is solidified to form a cast portion metallurgically bonded to the second layer. An aperture of the preform forms a port in fluid communication with a passage of the cast portion. A plurality of dome-shaped preforms may define the combustion chambers of a cylinder head formed by the method. The preform may define a cylinder head face. The first layer may be a steel-based layer, and the second layer and cast portion may be aluminum-based, such that the first layer and combustion surface has higher thermal fatigue strength relative to the cast portion.

Abstract: A method comprising introducing a first casting material into a casting mold; applying directional solidification to the first casting material in the casting mold; introducing a second casting material into the casting mold, the second casting material having a different chemical composition than the first casting material; applying directional solidification to the second casting material in the casting mold; and forming a molded article, wherein the molded article comprises a first region

Abstract: The invention relates to reactive metallic systems and to methods of producing reactive metallic systems. Such systems consist of metallic particles in the form of powders or pastes, or of metallic multilayer structures. To prevent the reaction product of the described self-propagating reactions from being a brittle material, it is suggested in the invention that the reactive metallic system be designed as a multilayer structure made up of thin layers of ruthenium and aluminium deposited sequentially one upon the other, or as a powder consisting of ruthenium and aluminium particles. The object is established according to the invention by selecting Ru/Al as the basic system. The strongest exothermic reaction and thus the greatest amount of liberated heat are to be expected from stoichiometrically constructed reactive systems. The heat of formation is highest here.

Abstract: A method of one-piece casting of a tool with a working component of steel and a body of grey iron, and an interconnection zone therebetween is carried out in a single mold which is kept closed and unchanged during the casting. The steel is cast first from beneath and upwards, whereafter a pause is made. The casting of the grey iron is only carried out when the temperature of the steel in the intended interconnection zone has fallen to a temperature corresponding to the liquidus temperature of the steel minus approx. 30° to 150° C.

Abstract: Molten metal of a first composition is fed into a mold cavity, via a first control apparatus, wherein the control apparatus is open, wherein the feeding comprises flowing out of a first feed chamber. The first control apparatus is closed. A second control apparatus is opened. Molten metal of a second composition is fed into the mold cavity, via the second control apparatus, wherein at least a portion of the metal of the first composition in the mold cavity is sufficiently molten so that an initial feed of molten metal of the second composition mixes with the molten metal of the first composition in the mold cavity, wherein the feeding comprises flowing out of a second feed chamber, wherein the second composition is different from the first composition.

Abstract: System and method of producing multi-layered aluminum alloy products are disclosed. A multi-layered aluminum alloy product may be formed by first heating a first aluminum alloy to a first temperature where the first temperature is at least about 5° C. lower than the eutectic temperature of the first aluminum alloy, second heating a second aluminum alloy to a second temperature where the second temperature is at least about 5° C. higher than the liquidus temperature of the second aluminum alloy, and coupling the second aluminum alloy to the first aluminum alloy to produce a multi-layered aluminum alloy product.

Abstract: Molten metal of a first composition flows out of a first chamber via an open first control apparatus into a mold cavity. The first control apparatus is closed. A second control apparatus is opened. Molten metal of a second composition, different from the first composition, flows out of a second feed chamber via the second control apparatus into the mold cavity. At least a portion of the first composition metal in the mold cavity is sufficiently molten that an initial feed of the second composition molten metal mixes with the first composition molten metal in the mold cavity. An ingot is removed from the mold cavity, the ingot having top, middle, and bottom sections, the bottom section composed of metal of the first composition, the top section composed of metal of the second composition, and the middle section composed of a mixture of metal of the first and second compositions.

Abstract: Skin material of a clad material is composed of one or more layers, each layer of the skin materials is made of a metal different from the core material in their component compositions, and at least one layer of the skin material has a cast microstructure, when the skin material is superposed on either of one or both faces of the core material.

Abstract: Equipment for manufacturing skin material of a clad material includes a casting apparatus which melts and mixes a metal for the skin material different from the core material in their component compositions, and casts the skin material; an ingot-cutting apparatus which cuts an ingot for skin material which is cast by the casting apparatus; and a conveying apparatus which conveys the ingot for skin material among each apparatus. The ingot-cutting apparatus is a slicing apparatus which slices the ingot for skin material into a predetermined thickness.

Abstract: A method for manufacturing a clad material composed of a core material and one or more skin materials which are superposed on either one or both faces of the core material, includes a clad material preparation process where an ingot for core material is manufactured by dissolving and casting a metal, and an ingot for skin material is manufactured by dissolving and casting a different metal for skin material, without hot rolling. The ingot for skin material is superposed as a skin material at a predetermined position of either one or both faces of the ingot for core material and the superposed material is hot-rolled to manufacture a clad material.

Abstract: A method for manufacturing a clad material composed of a core material and one or more skin materials which are superposed on either one or both faces of the core material, includes a clad material preparation process where an ingot for core material is manufactured by melting and casting a metal, and an ingot for skin material is manufactured by melting and casting a different metal for skin material, without hot rolling. The ingot for skin material is superposed as a skin material at a predetermined position of either one or both faces of the ingot for core material and the superposed material is hot-rolled to manufacture a clad material.

Abstract: The invention relates to a method for producing a light metal or plastic cylinder crankcase (2) of an internal combustion engine having a closed-deck design, comprising the steps of —casting a cylinder liner (4) using salt cores (6) corresponding at least to the cavities of the water jackets, —encapsulating the pre-cast cylinder liner in a pressure die-casting process in a light metal melt in order to achieve the cylinder crankcase (2) having a closed-deck design, wherein the cylinder liner (4) still contains the salt cores (6) at least in the water jackets during encapsulation.

Abstract: A method of one-piece casting of a tool with a working component of steel and a body of grey iron, and an interconnection zone therebetween is carried out in a single mould which is kept closed and unchanged during the casting. The steel is cast first from beneath and upwards, whereafter a pause is made. The casting of the grey iron is only carried out when the temperature of the steel in the intended interconnection zone has fallen to a temperature corresponding to the liquidus temperature of the steel minus approx. 30° to 150° C.

Abstract: A vertical casting process for an intermediate product, including the steps of (a) preparation of at least two aluminum based alloys, particularly a first alloy with composition P and a second alloy with composition T, (b) casting of the first alloy with composition P to a required height HP, and (c) casting of an additional required height HT of the alloy with composition T. The object of this invention is the manufacture of monolithic structural elements with working properties that are variable in at least one direction, and particularly bi-functional or multi-functional structural elements capable of performing at least two functions that are traditionally performed by two different parts.

Abstract: A method for producing a functionally gradient component, such a component having an outer layer of a first material, and an inner core of a second material, there being a gradual change in microstructure across the interface between the two materials, the method having particular application in producing a component formed from two or more aluminium alloys based on the aluminium-silicon (Al—Si) system, the method involving introducing a first molten metal into a mould, and allowing a layer of the first metal to partially solidify against a wall of the mould, decanting the remaining molten portion of the first metal, and introducing a second molten metal into the mould and allowing same to solidify.

Abstract: Molten metal of a first composition is fed into a mold cavity, via a first control apparatus, wherein the control apparatus is open, wherein the feeding comprises flowing out of a first feed chamber. The first control apparatus is closed. A second control apparatus is opened. Molten metal of a second composition is fed into the mold cavity, via the second control apparatus, wherein at least a portion of the metal of the first composition in the mold cavity is sufficiently molten so that an initial feed of molten metal of the second composition mixes with the molten metal of the first composition in the mold cavity, wherein the feeding comprises flowing out of a second feed chamber, wherein the second composition is different from the first composition.

Abstract: A cost-effective and highly reproducible method of fabricating nanowires, and small gaps or spacings in nanowires is disclosed. The nanogaps bridge an important size regime between 1 nm and 100 nm. The nanogaps can be selectively predetermined to be as small as 1.0 nm, or larger than 1000 nm. These electrode gaps can be useful in preparing molecular electronic devices that involve making electrical contact to individual molecules, such as biomolecules, or small clusters of molecules. Microelectrodes having nanogaps for electrical and magnetic applications formed by the method, and as well as biosensors and their use in detecting a biological species, such as DNA, are also disclosed.

Abstract: A method of producing a clad sheet article having superplastic properties, and the resulting clad sheet article. The method involves producing a cladding layer onto at least one rolling face of a core ingot made of a metal having superplastic properties, preferably by co-casting, to form a clad ingot and then rolling said clad ingot to produce a sheet article. The core ingot includes an element that diffuses from an interior of the ingot to a surface at superplastic forming temperatures thereby deteriorating surface properties of the ingot. The cladding layer is provided with an element (dopant) that reacts with the element of the core to reduce the ability of the element to diffuse through the cladding layer.

Abstract: An armature for use in an electric traction motor comprises a rotor having a central portion and a peripheral portion with the peripheral portion having a plurality of cavities. Permanent magnets solidified from liquid magnetic material are disposed in the cavities to form poles of the rotor with at least a portion of the cavities having directly abutting permanent magnets comprised of at least first and second magnetic materials of different properties injected in liquid or mobile form into single cavities. In interface regions between the at least first and second magnetic materials the first and second magnetic materials are intermingled to form a transition zone. A method of making the armature includes injecting the magnetic materials simultaneously as well as injecting a subsequent magnetic material when the initial magnetic material is still fluidly mobile.

Abstract: A method of manufacturing composite parts for an apparatus handling abrasive fluids and an apparatus for handling abrasive slurries, for example, a centrifugal pump. Portions of the composite parts are cast in a two-stage process. Portions to be machined are cast in a material suitable for machining and portions exposed to abrasive slurries are cast in a material that is wear-resistant.

Abstract: The present invention provides a method for producing a functionally gradient component, such a component having an outer layer of a first material, and an inner core of a second material, there being a gradual change in microstructure across the interface between the two materials, the method having particular application in producing a component formed from two or more aluminium alloys based on the aluminium-silicon (Al—Si) system, the method involving introducing a first molten metal into a mould, and allowing a layer of the first metal to partially solidify against a wall of the mould, decanting the remaining molten portion of the first metal, and introducing a second molten metal into the mould and allowing same to solidify.

Abstract: A stent having marker tabs formed from a micro-alloyed combination of materials provides for more precise placement and post-procedural visualization in a vessel, by increasing the radiopacity of the stent under X-ray fluoroscopy. A unique micro-alloying process is utilized to form the tabs, comprising a first alloy and a second alloy, wherein one of these alloys is radiopaque. This substantially eliminates the possibility of galvanic action between the tab and the stent. This process is also applicable to other medical devices.

Abstract: The present invention provides improved heated manifolds, heaters and nozzles for injection molding, having a high strength metal skeleton infiltrated with a second phase metal having higher thermal conductivity. Also disclosed is method of forming a manifold, heater or nozzle preform and infiltrating the preform with a highly thermally conductive material. The invention also provides a method of simultaneously infiltrating and brazing injection molding components of similar or dissimilar materials together.

Abstract: A method of manufacturing a camshaft used in an internal combustion engine. The method of manufacturing the camshaft produces a camshaft which has reduced weight and added wear resistance at a lobe of the camshaft. The camshaft is manufactured to provide increased efficiency of the internal combustion engine. The method of making the camshaft includes mixing wear resistant material with a base material and metering the mixture into a rotating die. The rotating die rotates at a predetermined speed and forces the wear resistant material to the outer surface of the lobes.

Abstract: The present invention provides improved heated manifolds, heaters and nozzles for injection molding, having a high strength metal skeleton infiltrated with a second phase metal having higher thermal conductivity. Also disclosed is method of forming a manifold, heater or nozzle preform and infiltrating the preform with a highly thermally conductive material The invention also provides a method of simultaneously infiltrating and brazing injection molding components of similar or dissimilar materials together.

Abstract: A process and apparatus for producing a brake drum or a brake disc include a carrier component formed of a light metal alloy which can be easily cast and machined and a friction lining component formed of a light metal alloy reinforced by short non-metallic fibers or particles by casting a first one of the components in a mold, cooling the cast component to achieve dimensional stability, casting the other component onto or around the first component, the components being designed to interlock mechanically as a unitary composite structure after cooling. The casting materials may be introduced into the die in a molten state or a thixotropic state. Core pullers are provided to create space in the die cavity for the second component after the first component has been cast and cooled to a dimensionally stable state.

Abstract: The present invention provides improved heated manifolds, heaters and nozzles for injection molding, having a high strength metal skeleton infiltrated with a second phase metal having higher thermal conductivity. Also disclosed is method of forming a manifold, heater or nozzle preform and infiltrating the preform with a highly thermally conductive material. The invention also provides a method of simultaneously infiltrating and brazing injection molding components of similar or dissimilar materials together.

Abstract: A bent pipe for use in piping arrangement for transporting materials conaining solids, the bent pipe being prepared by subjecting to high-frequency bending work a straight blank pipe prepared by centrifugal casting and having a plurality of layers. The straight blank pipe comprises an outer layer made of a steel having high weldability, and an inner layer made of a high Cr cast iron containing at least Cr in an amount of 10 to 35 wt. % and having high wear resistance, the outer layer and the inner layer being metallurgically joined. Preferably, a barrier layer is provided between the outer layer and the inner layer for preventing an alloy component in each of the layers from diffusing into the other layer. The barrier layer is preferably about 10 to about 100 &mgr;m in thickness.

Abstract: An impeller shoe (110) having a front side (112) with a series of half column members (114) and raised upper and lower rims (116, 118) that form the impact surface of the impeller shoe. Half columns (114) and raised rims (116, 118) are formed with carbide material (120) formed therein in order to improve wear resistance at these critical surfaces.

Abstract: The castings are cast in several casting slices. The casting slices of a casting are cast, staggered timewise in succession using the same method and from the same alloy but in different casting molds or different parts of a casting mold. At the seams, the casting slices are cast together along a defined shapewise contour. The casting slices can be cast together indirectly with interposition of a separate seam strip. However, they can also be cast onto one another, with an already cast first casting slice being placed in a second casting mold and cast together therein with the second casting slice. Complete body side wall parts are cast in three casting slices, with the seams being located in the roof and sill areas.

Abstract: A first cavity is formed between a mold and a core. One of a cylinder block material and a liner material is supplied to the first cavity. A second cavity is formed by expanding or shrinking the core or replacing the core with another core. The other of the cylinder block material and the liner material is supplied to the second cavity. The cylinder block with a liner is produced successively using the same apparatus.

Abstract: A method of manufacturing a cylinder block comprising one or more cylinders, the or each cylinder being adapted to receive a piston therein, the method comprising making a cylinder liner by squeeze casting, in an aluminium-silicon alloy produced from a melt consisting essentially of the following composition by weight: Silicon 14% to 16%; Copper 1.9% to 2.2%; Nickel 1.0% to 1.4%; Magnesium 0.4% to 0.55%; Iron 0.6% to 1.0%; Manganese 0.3% to 0.6%; Silicon Modifier 0.02% to 0.1%, with the balance being aluminium and any avoidable impurities, the cylinder liner having an essentially eutectic microstructure containing not more than 10% primary alpha-aluminium dendrites and being substantially free from intermetallic particles exceeding 10 .mu. in diameter, placing the cylinder block in a mold and casting therearound an aluminium alloy to provide a main cylinder block body with the cylinder liner entrapped therein.

Abstract: A roll outer layer material for hot rolling includes, as analyzed in weight percent, of 2.5-4.0% C, 6.0-20% Cr, 3.0-10.0% V, 0.6-5.0% Nb, 2.0-15% Mo, 3.0% or below Si, 3.0% or below Mn, C, V, Nb and Cr satisfying a following formula (1),10.5(%).ltoreq.6.5.C(%)-1.3.V(%)-0.7.Nb(%).ltoreq.2.Cr(%)-2(%)(1), and the balance being Fe and incidental impurities. A method of manufacturing a roll for hot rolling includes the steps of centrifugally casting an outer layer material having the above composition, centrifugally casting graphite steel containing 0.5% or above of C as an intermediate layer, and casting an axis material which is a spheroidal graphite cast iron, a flake graphite cast iron or a graphite steel. C is present in the intermediate layer in an amount which satisfies a following formula (2),C (intermediate layer).gtoreq.2.0-0.5 (C-0.2 V-0.

Abstract: The invention is directed to a golf club head and, more specifically, to a putter. In addition, the invention is directed to a method of manufacturing a golf club head. The putter head includes a first body element made of a high density first material, constituting at least the heel portion, the toe portion and a major portion of the surface of the sole, and a second body element intimately linked to the first element, the second element being made of a second metallic material of lower density, the second element covering the remainder of the head including at least the central portion of the striking face thereof.

Abstract: A generally annular rotor insert is formed by casting a metal matrix composite. The rotor insert includes a pair of brake friction plates which are disposed in mutually spaced apart relationship. The brake friction plates include inner surfaces and generally parallel outer surfaces. At least one of the inner surfaces of the brake friction plates is provided with a plurality of spacing elements for engagement with the inner surface of the other one of the brake friction plates for maintaining the plates in predetermined spaced apart relationship. The rotor insert is placed in a rotor mold. A hat-shaped rotor body is cast in the rotor mold whereby the spacing elements are effective to maintain the plates in a predetermined spaced apart relationship.

Abstract: A process is disclosed for the production of cast cylinder heads made of aluminium alloys from at least two different "liquid" alloys. The liquid alloys at the time of casting may contain solid particles of varied size and shape so as to produce composites with a metal matrix after solidifying. The process for moulding composite cylinder heads includes a number of successive layers consisting of at least two different alloys and consists in casting each alloy layer in the cavity of a mould via a feed system with a waiting time between the end of casting of one layer and the beginning of the second layer, so that the first layer contains between 50 and 100% of solid fraction in its lower part and 0 to 80% of solid fraction in the upper part, the interface region, when the second alloy is introduced.

Abstract: A method is provided for producing by centrifugal casting an alloy tubular article of manufacture in the form of a composite tubular product comprised of an outer alloy layer (first alloy) and at least one inner alloy layer (second alloy) while substantially inhibiting the formation of a metallurgical bond between layers in the final casting. The product is produced using a rotatable centrifugal casting mold having a cylindrical inner surface adapted to receive a molten metal alloy. A first layer of an alloy is poured into the rotatable mold, the alloy having a melting point of at least about 1300.degree. C. and generally at least about 1400.degree. C. Centrifugally casting said alloy as an outer layer during rotation of said mold. The outer layer is solidified and cooled to a temperature not exceeding about 92% of its absolute melting point in degrees Kelvin. At least one inner layer is poured into the outer layer, the alloy of the inner having a melting point of at least about 1300.degree. C.

Abstract: The compound roll having a shell portion made of a hard, high-alloy cast steel or iron having excellent wear resistance and resistance to surface roughening and a core portion made of a tough cast iron or cast steel, the cast iron of the shell portion having a composition consisting essentially, by weight ratio, of 1.0-3.0% of C, 2.0% or less of Si, 2.0% or less of Mn, 2.0-15.0% of Cr, 10.0% or less of Mo, 2.0-8.0% of V, the balance being substantially Fe and inevitable impurities, an average diameter of crystal grains constituting a matrix of the metal structure of the shell portion being 100 .mu.m or less in a range from a surface to a depth of 50 mm when determined by an image analysis method on the crystal grains having diameters exceeding 30 .mu.m, and the crystal grains satisfying the formula: m.sub.2 .ltoreq.1.2 m.sub.1, wherein m.sub.1 is an average diameter of the crystal grains at the surface of the shell portion, and m.sub.