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Selection of common casting materials |
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| Material | Features and Applications |
| Grey cast iron | Good fluidity, small shrinkage rate during cooling, low strength, plasticity and toughness, elastic modulus varies between 80000~140000MPa with different microstructures, compressive strength is 3~4 times higher than tensile strength, wear-resistant Good performance and vibration absorption. It is not sensitive to cuts and has good cutting performance. Welding performance is poor. It cannot be used for a long time above 300~400℃. 85%~90% rate of cast iron products. |
| Malleable cast iron | The casting performance is worse than that of gray cast iron and better than that of cast steel. It is used to manufacture small thin-walled castings that have certain requirements for strength and toughness. Good corrosion resistance and good processing performance. The impact toughness is 3~4 times larger than that of gray cast iron. |
| Ductile Iron | The casting performance is worse than that of gray cast iron, and it is prone to defects. The cutting performance is good, and the heat treatment can make its performance change in a wide range. The tensile strength is higher than that of cast iron and cast steel, and the ratio of yield strength to tensile strength is higher than malleable cast iron and steel. The plasticity is the best in cast iron, and the impact toughness is not as good as that of steel, but much larger than that of gray cast iron. Has good low temperature performance. The fatigue strength is high, close to 45 steel, but the sensitivity to stress concentration is lower than that of steel. Good wear resistance, heat resistance and corrosion resistance. The vibration attenuation ratio of steel, ductile iron and gray iron is 1:1.8:4.3. increasingly widely used as important parts. |
| Compacted Graphite Iron | The mechanical properties of vermicular graphite cast iron are between gray cast iron and ductile iron, and it has good compactness, heat resistance and wear resistance. Its casting performance is better than that of ductile iron and close to that of gray cast iron. Its strength is similar to that of ductile iron, and it has similar anti-vibration, thermal conductivity and casting properties to gray iron, but better plasticity and fatigue resistance than gray iron.Compacted graphite cast iron will inevitably contain a certain amount of nodular graphite. The increase of nodular graphite will increase its strength and rigidity, but at the expense of impairing the cast ability of molten iron and deteriorating the workability and thermal conductivity of castings. |
| cast steel | The casting performance is relatively poor, the fluidity is poor, and the shrinkage is large, but it has higher comprehensive mechanical properties, that is, higher strength, toughness and plasticity. Tensile strength and compressive strength are nearly equal. Some special cast steels have special properties such as heat resistance and corrosion resistance |
| Cast aluminum alloy | Aluminum alloys are only 1/3 the density of iron and are used to make various light structures. Some aluminum alloys can be strengthened by heat treatment to make them have better comprehensive properties. As the wall thickness increases, the strength decreases significantly. |
| cast bronze | It is divided into two categories: tin bronze and Wuxi bronze. Tin bronze has good wear and corrosion resistance, high strength and hardness, poor casting performance, and is prone to segregation and shrinkage. Quenching has no strengthening effect. Wuxi bronze is commonly used in aluminum bronze or lead bronze, which has poor casting performance. Aluminum bronze has high strength, wear resistance and corrosion resistance. Lead bronze has high fatigue strength, strong thermal conductivity and acid resistance |
| Cast Brass | Larger shrinkage, generally high strength, good plasticity, good corrosion resistance and wear resistance. Good cutting performance |
| Comparison of common cast iron materials for casting | ||||
| Type of Iron | Grey Iron | Malleable Iron | Ductile Iron | Compacted Graphite Iron |
| Graphite Form | Flake | Flocculent | Spherical | Worm-like |
| Overview | Cast iron obtained by fully conducting the first-stage | White cast iron is a high-strength and tough cast iron obtained by graphitization annealing treatment to obtain nodular graphite through spheroidization and inoculation treatment to obtain vermicular graphite through vermicularization and inoculation treatment | Nodular graphite obtained by spheroidization and inoculation treatment | Vermicular graphite obtained by vermicularization and inoculation treatment |
| Castability | Good | Worse than grey cast iron | Worse than grey cast iron | Good |
| Machining performance | Good | Good | Good | Good |
| Abrasion resistance | Good | Good | Good | Good |
| Strength/Hardness | Ferrite: LowPearlite: higher | higher than grey cast iron | very high | higher than grey cast iron |
| Plasticity/Toughness | very low | close to cast steel | very high | higher than grey cast iron |
| Application | Cylinder, flywheel, piston, brake wheel, pressure valve, etc. | Small and medium-sized parts with complex shapes that are impacted, such as wrenches, farm implements, gears | Parts with high strength and toughness requirements, such as internal combustion engine crankshafts, valves | Parts that are durable under thermal shock, such as diesel engine cylinder heads |
| Remark | low notch sensitivity | Can not be forged | High heat resistance, corrosion resistance, fatigue strength (twice gray cast iron) | Thermal conductivity, thermal fatigue resistance, growth resistance and oxidation resistance |
Post time: Nov-02-2022