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How does cast iron fracture?
In this case, as the tensile stress increases, microvoids nucleate at inclusions and second-phase particles. Further increase in tension causes the voids to grow until they contact neighboring voids to form a macroscopic crack, which leads to fracture.
What causes fracture toughness?
The fracture toughness of metals and other ductile materials is dependent on their thickness. The toughness is highest when plane stress conditions exist at the crack tip, and this occurs when the material is thin (typically less than several millimetres).
What causes fracture in casting?
Fracture occurs when the ability to plastically deform under load is exhausted. The chief cause of the plastic deformation is the movement of dislocations and the resistance to its movement causes increased plastic flow stress and abetment of fracture.
What is the toughness of cast iron?
Although cast irons are generally perceived as being low in toughness, the toughness values measured on fully ferritic nodular iron were quite high (KIc = 80 to 106 MPa√m [73 to 96 ksi√in.] on the upper shelf).
Which is good for health cast iron or iron?
You’ll use less oil, avoid harmful chemicals, and get a little extra iron in your diet.
What is the difference between toughness and fracture toughness?
Toughness is the ability of material (assumed to perfect, meaning no cracks) to absorb energy to fracture. It is measured by the area under stress strain curve to the point of fracture. Fracture Toughness is the ability of material with pre-cracks to resist fracture by absorbing energy.
What is meant by fracture toughness?
In metallurgy, fracture toughness refers to a property which describes the ability of a material containing a crack to resist further fracture. Fracture toughness is a quantitative way of expressing a material’s resistance to brittle fracture when a crack is present.
How do you get rid of porosity in castings?
Gas porosity can be eliminated through good mould design or by introducing nitrogen into the aluminium metal before the liquid pour. HiPping can also be used to eliminate small amounts of porosity inside the casting.
How is cast iron obtained?
It is made by reducing iron ore in a blast furnace. The liquid iron is cast, or poured and hardened, into crude ingots called pigs, and the pigs are subsequently remelted along with scrap and alloying elements in cupola furnaces and recast into molds for producing a variety of products.
Which of the following cast irons Cannot be machined?
Which of the following cast irons cannot be machined? Explanation: White cast irons are used where hardness and wear resistance matter, like grinding and crushing. Since it is hard, it cannot be machined. Grey and malleable cast irons, on the other hand, have excellent machinability.