National standard QT700-2 high toughness ductile iron price

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Sales Hotline: manager Chen: 135-56711299, Tel: 0769-81287858, fax: 0769-81287898, qq:496265553  Ductile iron
A general term for an alloy consisting mainly of iron, carbon, and silicon
In these alloys, the carbon content exceeds the amount that can be retained in austenite solid solution at eutectic temperature
Cast iron is a general term for alloys composed mainly of iron, carbon and silicon
In these alloys, the carbon content exceeds the amount that can be retained in austenite solid solution at eutectic temperature

 
Iron carbon alloy with carbon content above 2%
Generally, the carbon content of industrial cast iron is 2% ~ 4%
Carbon in cast iron mostly exists in the form of graphite and sometimes in the form of cementite
In addition to carbon, cast iron also contains 1% ~ 3% silicon, manganese, phosphorus, sulfur and other elements
Alloy cast iron also contains nickel, chromium, molybdenum, aluminum, copper, boron, vanadium and other elements
Carbon and silicon are the main elements that affect the microstructure and properties of cast iron

 
Cast iron can be divided into
① Grey cast iron
The carbon content is high (2
7% ~ 4
0%), the carbon mainly exists in the form of flake graphite, and the fracture is gray, referred to as gray iron for short
Low melting point (1145 ~ 1250 ℃), small shrinkage during solidification, compressive strength and hardness close to carbon steel, and good shock absorption
Used for manufacturing machine tool bed, cylinder, box and other structural parts

② White cast iron
The content of carbon and silicon is low, carbon mainly exists in the form of cementite, and the fracture is silver white
During solidification, shrinkage is large, and shrinkage cavities and cracks are easy to occur
High hardness and brittleness, unable to bear impact load
It is often used as a blank of malleable cast iron and to make wear-resistant parts

③ Malleable iron
Obtained from annealed white cast iron, graphite is distributed in flocculent form, which is called ductile iron for short
It has uniform microstructure and properties, wear resistance, good plasticity and toughness
It is used to manufacture parts with complex shape and can bear strong dynamic load

④ Ductile iron
Gray cast iron is obtained by spheroidizing molten iron, and the precipitated graphite is spherical, which is called nodular iron for short
It has higher strength, better toughness and plasticity than ordinary gray cast iron
It is used for manufacturing internal combustion engines, auto parts, agricultural machinery, etc

⑤ Vermicular graphite cast iron
The graphite precipitated from the hot metal of gray cast iron is vermicular
The mechanical properties are similar to that of nodular cast iron, and the casting properties are between that of gray cast iron and nodular cast iron
Used to make automobile parts

⑥ Alloy cast iron
Ordinary cast iron is obtained by adding appropriate amount of alloy elements (such as silicon, manganese, phosphorus, nickel, chromium, molybdenum, copper, aluminum, boron, vanadium, tin, etc
)
Alloy elements change the matrix structure of cast iron, which has the corresponding characteristics of heat resistance, wear resistance, corrosion resistance, low temperature resistance or non-magnetic
It is used for manufacturing parts of mining, chemical machinery, instruments and meters

⑦ Austenitic cast iron
Cast iron with stable austenitic matrix at room temperature, including austenitic grey cast iron and austenitic nodular cast iron, is made of iron, carbon, nickel, silicon, manganese, copper and chromium

Classification of cast iron
Classification method classification name Description
1
according to fracture color
(1) Gray cast iron is a kind of cast iron in which most or all of the carbon is in the form of free state flake graphite
Its fracture surface is dark gray
It has certain mechanical properties and good machinability
It is widely used in industry
(2) White cast iron white cast iron is a kind of iron carbon alloy with no or almost no graphite in the structure
Its fracture is white, hard and brittle, and can not be cut
It is rarely used to make mechanical parts in industry
Because of its high surface hardness and wear resistance, it is also called chilled cast iron or chilled cast iron
  (3) Hemp cast iron hemp cast iron is a kind of cast iron between white cast iron and gray cast iron
Its fracture is gray and white pitting, which has poor performance and is rarely used
 
2
by chemical composition
(1) Ordinary cast iron refers to cast iron without any alloy elements, such as gray cast iron, malleable cast iron, ductile iron, etc
(2) Alloy cast iron is a kind of high-grade cast iron prepared by adding some alloy elements into ordinary cast iron to improve some special properties
Such as various cast iron with special properties of corrosion resistance, heat resistance and wear resistance
 
3
according to production method, structure and performance
(1) Common grey cast iron see “ Grey cast iron ”
(2) Inoculated cast iron “ Metamorphism ” It is also called modified cast iron
Its strength, plasticity and toughness are much better than those of common gray cast iron, and its structure is also more uniform
It is mainly used to manufacture large castings with high mechanical properties and large changes in section size
(3) Malleable cast iron malleable cast iron is made of white cast iron with certain composition by graphite annealing
It has higher toughness than gray cast iron, also known as ductile cast iron
It can not be forged, and is often used to make castings bearing impact loads
(4) Ductile iron is abbreviated as ductile iron
It is obtained by adding a certain amount of spheroidizing agent and inking agent to the molten iron before casting to promote the crystallization of spheroidal graphite
Compared with steel, it has similar properties except lower plasticity and toughness
It is an excellent material with the advantages of both steel and cast iron
It is widely used in mechanical engineering
(5) Special performance cast iron this is a kind of cast iron with certain characteristics
According to different uses, it can be divided into wear-resistant cast iron, heat-resistant cast iron, corrosion-resistant cast iron, etc
Most of them belong to alloy cast iron and are widely used in mechanical manufacturing
 
Cast iron - heat treatment process
1
stress relief annealing due to the uneven wall thickness of the casting, the effective stress and structural stress will be generated during the heating, cooling and phase transformation process
In addition, large parts are also prone to residual stress after machining, and all these internal stresses must be eliminated
The usual heating temperature for stress relief annealing is 500 ~ 550 ℃, the holding time is 2 ~ 8h, and then furnace cooling (gray iron) or air cooling (ductile iron)
90 ~ 95% of the internal stress of the casting can be eliminated by this process, but the structure of the cast iron does not change
If the temperature exceeds 550 ℃ or the holding time is too long, it will cause graphitization and reduce the strength and hardness of the casting

2
eliminate high temperature graphitization annealing of white cast iron
When the casting is cooled, the surface layer and thin section often produce white spots
The white mouth structure is hard and brittle with poor processability and easy to peel off
Therefore, annealing (or normalizing) must be used to eliminate the white structure
Annealing process: heating to 550-950 ℃ for 2-5 hours, then furnace cooling to 500-550 ℃ and air cooling
During the high-temperature insulation period, the hypercementite and eutectic cementite decompose into graphite and A
in the subsequent cooling protection process, the secondary cementite and eutectoid cementite also decompose, resulting in the graphitization process
Due to the decomposition of cementite, the hardness decreases and the machinability is improved

3
normalizing of ductile iron
The purpose of normalizing ductile iron is to obtain pearlitic matrix structure, refine grain size and uniform structure, so as to improve the mechanical properties of castings
Sometimes, normalizing is also the preparation for the structure of ductile iron surface quenching
Normalizing can be divided into high-temperature normalizing and low-temperature normalizing
The high-temperature normalizing temperature is generally not more than 950 ~ 980 ℃, and the low-temperature normalizing is generally heated to the fold temperature range of 820 ~ 860 ℃
Generally, four persons are required to deal with after normalizing to eliminate the internal stress generated during normalizing

4
quenching and tempering of ductile iron
In order to improve the mechanical properties of ductile iron, the castings are generally heated to 30 ~ 50 ℃ above Afc1 (Afc1 represents the end temperature of a formation during heating), and quenched into oil after heat preservation to obtain martensitic structure
In order to properly reduce the residual stress after quenching, tempering should be carried out after quenching
The low-temperature tempering structure is tempered martensite plus residual bainite and spheroidal graphite
This structure has good wear resistance and is used for parts requiring high wear resistance and high strength
The medium temperature tempering temperature is 350-500 ℃
After tempering, the microstructure is tempered troostite plus spheroidal graphite
It is suitable for thick parts requiring good wear resistance, certain effective stability and elasticity
Mingwan company - relevant talents are mainly concentrated in the iron and steel talent network
The high-temperature tempering temperature is 500-60d ℃
After tempering, the microstructure is tempered Soxhlet plus spheroidal graphite
The microstructure with good combination of toughness and strength is 500-60d ℃
After tempering, the microstructure is tempered Soxhlet plus spheroidal graphite
It has good comprehensive properties of toughness and strength, so it is widely used in production

5
multi temperature quenching of ductile iron
After austempering, ductile iron can obtain high strength, good plasticity and toughness
The choice of heating temperature for multi temperature quenching mainly considers that the original structure is A-shaped, no residual f is left, and the a grain growth is avoided at the same time
The heating temperature is generally 30 ~ 50 ℃ above Afc1, and the isothermal treatment temperature is 0 ~ 350 ℃ to ensure the lower bainite structure with comprehensive mechanical properties
Rare earth mg Al ductile iron after austempering σ b=1200～1400MPa，α k=3～3
6J／cm2，HRC＝47～51。 However, it should be noted that a tempering process should be added after isothermal quenching

6
surface quenching
In order to improve the surface hardness, wear resistance and fatigue strength of some castings, surface quenching can be used
Both gray cast iron and ductile iron castings can be surface quenched
Generally, high (medium) frequency induction heating surface quenching and electric contact surface quenching are used

7
chemical heat treatment
For castings requiring wear resistance, oxidation resistance and corrosion resistance on the surface, chemical heat treatment process similar to steel can be adopted, such as gas soft chlorination, chlorination, boriding, sulfurizing, etc

Grey cast iron
GB China   HT100  HT150  HT200  HT250   HT300  HT350
JIS Japan   FC100  FC150  FC200  FC250  FC300  FC350
KS Korea gc100  GC150  GC200  GC250  GC300  GC350
AWS USA no
20  NO
25  NO
30  NO
35  NO
40  NO
45 
NO
50  NO
55  NO
60
UNS USA f11401  F11701  F12101  F12801  F13101  F14101
 
Ductile iron
GB China qt400-18  QT400-15  QT450-10  QT500-7   QT600-3   QT700-2  QT800-2  QT900-2
JIS Japan fcd350-22  FCD400-18  FCD400-15  FCD450-10  FCD500-7  FCD600-3  FCD700-2  FCD800-2
KS Korea gcd370  GCD400  GCD450  GCD500  GCD600  GCD700  GCD800
AWS USA 60-40-18  65-45-12  80-55-06  100-70-03  120-90-02
UNS USA f32800  F33100  F33800  F34800  F36200 
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Special specifications can be customized
Mingwan company welcomes your calls, and we will serve you sincerely
Sales Hotline: manager Chen: 135-56711299, Tel