Table of Contents
- 1 What is the effect of having larger graphite flakes in cast iron?
- 2 Why are graphites formed in cast iron?
- 3 Which cast iron shows better damping capacity and why?
- 4 Which phase is responsible for the damping capacity of gray cast iron?
- 5 How might the graphite influence the ductility in the iron?
- 6 What is damping property?
- 7 What determines the specific damping capacity of cast irons?
- 8 What makes greygrey cast irons so soft?
- 9 What are the characteristics of graphite flakes?
What is the effect of having larger graphite flakes in cast iron?
The strength of gray cast iron depends on the matrix in which graphite (free carbon) is embedded. The matrix can range from ferrite to pearlite and various combinations of the two phases. Large graphite flakes reduce the strength and ductility, so inoculants are used to promote fine flakes.
Why are graphites formed in cast iron?
A high cooling rate and a low carbon equivalent favours the formation of white cast iron whereas a low cooling rate or a high carbon equivalent promotes grey cast iron. During solidification, the major proportion of the carbon precipitates in the form of graphite or cementite.
Which cast iron shows better damping capacity and why?
Lamellar graphite cast iron (GJL types) has the highest damping capacities by far. It achieves values which can be 100 times higher as those of other types of steel.
Why does cast iron absorb vibrations?
Why cast iron absorb vibrations? – Quora. Damping capacity which is the special character in the cast iron . Cast iron having graphite as flakes which has absorb external force and distribute to its whole surface . So that vibrations Were reduced… by this excellent character all the automobile industries using castings …
What is the effect of phosphorus and Sulphur in cast irons?
7. What is the effect of phosphorus and sulphur in cast irons? Explanation: Although sulphur stabilizes cementite, it causes brittleness. The same is true for phosphorus, due to which both elements are limited to a minimum quantity.
Which phase is responsible for the damping capacity of gray cast iron?
graphite phase
The development of grey cast iron which exhibits a high damping capacity, requires then lamellar graphite phase possibly doped with intercalated impurities. Grey cast iron can be considered as a two phase material composed of a matrix containing graphite precipitates.
How might the graphite influence the ductility in the iron?
Spheroidal graphite CI usually has a pearlitic matrix. Annealing, however, causes the carbon in the pearlite to precipitate onto the existing graphite or to form further small graphite particles, leaving behind a ferritic matrix. This gives the iron even greater ductility (i.e. grade 60-40-18).
What is damping property?
Damping capacity is a mechanical property of materials that measure a material’s ability to dissipate elastic strain energy during mechanical vibration or wave propagation. Low damping materials may be utilized in musical instruments where sustained mechanical vibration and acoustic wave propagation is desired.
What is damping material?
Damping materials reduce or eliminate the damaging forces caused by mechanical or electrical energy (i.e., vibrations, movement, or noise). The performance of a damping material depends on the combined characteristics of the material and the environment in which it is used.
What is the effect of sulphur on the properties of cast iron?
Sulfur is generally considered a tramp element in cast iron, and its level must be controlled. 1-4 When manganese is not present at sufficient concentrations, sulfur reacts with iron to produce a low-melting phase (FeS) that may produce hot- shortness.
What determines the specific damping capacity of cast irons?
In cast irons, the lowest damping capacity is associated with nodular graphite microstructure, and the specific damping capacity (SDC) increases as the graphite micro structure progresses from nodular to compacted to flake. Predominant ferrite in cast irons is also associated with good damping.
What makes greygrey cast irons so soft?
Grey cast irons are softer with a microstructure of graphite in transformed-austenite and cementite matrix. The graphite flakes, which are rosettes in three dimensions, have a low density and hence compensate for the freezing contraction, thus giving good castings free from porosity.
What are the characteristics of graphite flakes?
The graphite flakes, which are rosettes in three dimensions, have a low density and hence compensate for the freezing contraction, thus giving good castings that are free from porosity. The flakes of graphite have good damping characteristics and machinability because the graphite acts as a chip-breaker and lubricates the cutting tools.
What is the percentage of graphite in grey cast iron?
Grey cast iron, Fe-3.2C-2.5Si wt\%, containing graphite flakes in a matrix which is pearlitic. The speckled white regions represent a phosphide eutectic. Etchant: Nital 2\%. Grey cast iron, Fe-3.2C-2.5Si wt\%, containing graphite flakes in a matrix which is pearlitic.